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DOI： 10.1128/jvi.01823-23

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Combination antiretroviral therapy (cART) has significantly improved the prognosis of individuals living with human immunodeficiency virus (HIV). Acquired immunodeficiency syndrome has transformed from a fatal disease to a treatable chronic infection. Currently, effective and safe anti-HIV drugs are available. Although cART can reduce viral production in the body of the patient to below the detection limit, it cannot eliminate the HIV provirus integrated into the host cell genome; hence, the virus will be produced again after cART discontinuation. Therefore, research into a cure (or remission) for HIV has been widely conducted. In this review, we focus on drug development targeting cells latently infected with HIV and assess the progress including our current studies, particularly in terms of the "Shock and Kill", and "Block and Lock" strategies.

DOI： 10.3390/ijms25052621

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BACKGROUND: Antibody testing can easily evaluate the clinical status of patients, aid in the diagnosis of multisystem inflammatory syndrome, and monitor the immunity level in the population. However, the applicability of serological tests in detecting antibodies against the severe acute respiratory syndrome 2 (SARS-CoV-2) spike-binding protein remains limited. This study aimed to quantify both serum-derived neutralizing immunoglobulin-G (IgG) antibody activity and the amount of anti-SARS-CoV-2 Spike-IgG (S-IgG) in convalescent sera/plasmas and evaluate the direct correlation between the in vitro IgG-EC50 values and S-IgG values. METHODS: We evaluated the neutralizing activity of purified IgG (IgG-EC50), quantified S-IgG in the serum/plasma of consecutive COVID-19 convalescent individuals using a cell-based virus-neutralizing assay, and determined the correlation between IgG-EC50 and S-IgG. In addition, we evaluated rational cut-off values using the receiver operating characteristic (ROC) curve and calculated the sensitivity and specificity of the quantitative S-IgG assay for moderate and high IgG-EC50. RESULTS: A high correlation was observed between S-IgG and IgG-EC50 with a Spearman's ρ value of -0.748 (95 % confidence interval [CI]: -0.804-0.678). Using an IgG-EC50 of 50 μg/mL and 20 μg/mL as the cut-off values for moderate and high in vitro neutralizing activity, respectively, the Youden's index values of 287.5 binding antibody units (BAU)/mL and 454.1 BAU/mL determined from the ROC curve showed the highest diagnostic accuracy, with Kappa values of 0.884 (95 % CI: 0.823-0.946) and 0.920 (95 % CI: 0.681-0.979), respectively. CONCLUSIONS: Quantitative S-IgG tests are a useful and convenient tool for estimating in vitro virus-neutralizing activity, with a high correlation with IgG-EC50 when the rational cut-off value is carefully determined.

DOI： 10.1016/j.heliyon.2024.e24513

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Convalescent plasma therapy, which involves administering plasma from recovered coronavirus disease 2019 (COVID-19) patients to infected individuals, is being explored as a potential treatment for severe cases of COVID-19. This study aims to evaluate the efficacy and safety of convalescent plasma therapy in COVID-19 patients with moderate to severe illness. An open-label, single-arm intervention study was conducted without a control group. Plasma collected from recovered COVID-19 patients was administered to eligible participants. The primary endpoint was the proportion of patients who were placed on artificial ventilation or died within 14 days of transfusion. Secondary endpoints included clinical improvement, viral load measurements, and adverse event monitoring. A total of 59 cases were included in the study. The primary endpoint was evaluated by comparing the rate obtained in the study to an existing rate of 25%. The study also assessed clinical improvement, viral load changes, and safety endpoints through adverse event monitoring. Convalescent plasma therapy shows potential as a treatment option for COVID-19. This study aimed to provide evidence for the efficacy and safety of this therapy and may contribute to its future use in treating severe cases of COVID-19.

DOI： 10.3390/life13112184

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BACKGROUND: We aimed to investigate chronological changes in the characteristics of participants in a coronavirus disease 2019 convalescent plasma donation study that may benefit optimal collection methods in the future. METHODS: Data from a convalescent plasma donation study from April 30, 2020 to November 5, 2021 were collected and analyzed. After August 23, 2021, an interim analysis of factors linked to higher antibody titers led us to restrict our participant recruitment criteria to participants who were within 4 months of disease onset and to patients who were otherwise most likely to have sufficiently high antibody titers. Overall, 1299 samples from 1179 patients were analyzed. RESULTS: Over the duration of the study, 35.9% of the samples were deemed eligible for convalescent plasma collection. The overall eligibility rate initially declined, dipping to <20% after one year. During this period, the proportion of enrolled samples from patients who had severe illness also declined, and the proportion of samples from participants who were >120 days post disease onset increased. After the addition of days from onset and vaccination status to our participant recruitment criteria, the eligibility rate improved significantly. CONCLUSIONS: As outbreaks of emerging infectious disease occur, it is desirable to construct and implement a scheme for convalescent plasma donation promptly and to monitor the eligibility rate over time. If it declines, promptly analyze and resolve the associated factors. Additionally, vaccine development and infection prevalence are likely to influence the effective recruitment of participants with high antibody titers.

DOI： 10.1016/j.heliyon.2023.e20568

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BACKGROUND: Data are limited on the role of preinfection humoral immunity protection against Omicron BA.5 infection and long coronavirus disease (COVID) development. METHODS: We conducted nested case-control analysis among tertiary hospital staff in Tokyo who donated blood samples in June 2022 (1 month before Omicron BA.5 wave), approximately 6 months after receiving a third dose of COVID-19 mRNA vaccine. We measured live virus-neutralizing antibody titers against wild type and Omicron BA.5, and anti-receptor-binding domain (RBD) antibody titers at preinfection, and compared them between cases and propensity-matched controls. Among the breakthrough cases, we examined association between preinfection antibody titers and incidence of long COVID. RESULTS: Preinfection anti-RBD and neutralizing antibody titers were lower in cases than controls. Neutralizing titers against wild type and Omicron BA.5 were 64% (95% confidence interval [CI], 42%-77%) and 72% (95% CI, 53%-83%) lower, respectively, in cases than controls. Individuals with previous Omicron BA.1/BA.2 infections were more frequent among controls than cases (10.3% vs 0.8%), and their Omicron BA.5 neutralizing titers were 12.8-fold higher than infection-naive individuals. Among cases, preinfection antibody titers were not associated with incidence of long COVID. CONCLUSIONS: Preinfection immunogenicity against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) may play a role in protecting against the Omicron BA.5 infection but not preventing long COVID.

DOI： 10.1093/infdis/jiad317

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Eradication of HIV-1 latently infected cells is an important issue in HIV treatment. However, there are limited models available to assess therapeutic efficacy in vitro. Here, we present a protocol for establishing a variety of HIV-infected Jurkat cells, including productive and latent status, evaluating the efficacy of antiviral agents, followed by PCR/sequencing-based detection of replication competent HIV provirus. This protocol is useful for optimization of treatment of HIV-1 and provides insights into the mechanisms of clonal selection of heterogeneous HIV-1-infected cells. For complete details on the use and execution of this protocol, please refer to Matsuda et al. (2021).1.

DOI： 10.1016/j.xpro.2023.102547

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Language：English   Publisher：エルゼビア・ジャパン(株)  

SARS-CoV-2に対する高い中和活性をもつ回復期血漿を用いた血漿療法を、高リスクCOVID-19患者に施行した。COVID-19症状出現から5日以内に血漿療法を始め、day 0～day 5の鼻咽頭拭い液のウイルス量の時間加重平均変化を主要評価項目とした。患者25名が無作為に回復期血漿療法群(n=14(うち4名は血漿療法を中止))と標準的治療群(n=11)に割り付けられた。症状出現から血漿投与までの日数の中央値は4.5日であった。day 0～day 5までのウイルス量の時間加重平均変化は血漿療法群で1.2log copies/mL、標準的治療群で1.2log copies/mLで、有意差はなかった。いずれの群にも死亡例はなかった。早期の回復期血漿投与はウイルス量低下に寄与しないと考えられた。

Language：English   Publishing type：Research paper (scientific journal)  

Cells latently infected with human immunodeficiency virus type 1 (HIV-1) prevent people living with HIV-1 from obtaining a cure to the infectious disease. Latency reversing agents (LRAs) such as protein kinase C (PKC) activators and histone deacetylase (HDAC) inhibitors can reactivate cells latently infected with HIV-1. Several trials based on treatment with HDAC inhibitors alone, however, failed to reduce the number of latent HIV-1 reservoirs. Herein, we have focused on a diacylglycerol (DAG)-lactone derivative, YSE028 (1), which is a PKC activator with latency reversing activity and no significant cytotoxicity. Caspase-3 activation of YSE028 (1) led to cell apoptosis, specifically in HIV-1 latently infected cells. Structure-activity relationship studies of YSE028 (1) have produced several useful derivatives. Among these, compound 2 is approximately ten times more potent than YSE028 (1) in reactivation of cells latently infected with HIV-1. The activity of DAG-lactone derivatives was correlated with the binding affinity for PKC and the stability against esterase-mediated hydrolysis.

DOI： 10.1016/j.ejmech.2023.115449

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BACKGROUND: Convalescent plasma is a potential therapeutic option for patients with coronavirus disease 2019 (COVID-19). Despite its use for treating several viral infections, we lack comprehensive data on its efficacy against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). METHODS: We conducted a multicenter, open-label, randomized controlled trial of convalescent plasma therapy with high neutralizing activity against SARS-CoV-2 in high-risk patients within five days after the onset of COVID-19 symptoms. The primary endpoint was the time-weighted average change in the SARS-CoV-2 viral load in nasopharyngeal swabs from days 0-5. RESULTS: Between February 24, 2021, and November 30, 2021, 25 patients were randomly assigned to either convalescent plasma (n = 14) or standard of care (n = 11) groups. Four patients discontinued their allocated convalescent plasma, and 21 were included in the modified intention-to-treat analysis. The median interval between the symptom onset and plasma administration was 4.5 days (interquartile range, 3-5 days). The primary outcome of the time-weighted average change in the SARS-CoV-2 viral load in nasopharyngeal swabs did not significantly differ between days 0-5 (1.2 log10 copies/mL in the convalescent plasma vs. 1.2 log10 copies/mL in the standard of care (effect estimate, 0.0 [95% confidence interval, -0.8-0.7]; P = 0.94)). No deaths were observed in either group. CONCLUSIONS: The early administration of convalescent plasma with high neutralizing activity did not contribute to a decrease in the viral load within five days compared with the standard of care alone.

DOI： 10.1016/j.jiac.2023.05.012

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BACKGROUND: Longitudinal data are lacking to compare booster effects of Delta breakthrough infection versus third vaccine dose on neutralizing antibodies (NAb) against Omicron. METHODS: Participants were the staff of a national research and medical institution in Tokyo who attended serological surveys on June 2021 (baseline) and December 2021 (follow-up); in between, the Delta-dominant epidemic occurred. Of 844 participants who were infection-naïve and had received two doses of BNT162b2 at baseline, we identified 11 breakthrough infections during follow-up. One control matched to each case was selected from boosted and unboosted individuals. We compared live-virus NAb against Wild-type, Delta, and Omicron BA.1 across groups. RESULTS: Breakthrough infection cases showed marked increases in NAb titers against Wild-type (4.1-fold) and Delta (5.5-fold), and 64% had detectable NAb against Omicron BA.1 at follow-up, although the NAb against Omicron after breakthrough infection was 6.7- and 5.2-fold lower than Wild-type and Delta, respectively. The increase was apparent only in symptomatic cases and as high as in the third vaccine recipients. CONCLUSIONS: Symptomatic Delta breakthrough infection increased NAb against Wild-type, Delta, and Omicron BA.1, similar to the third vaccine. Given the much lower NAb against Omicron BA.1, infection prevention measures must be continued irrespective of vaccine and infection history while the immune evasive variants are circulating.

DOI： 10.1186/s12879-023-08272-2

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Although vaccines for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) disease 2019 (COVID-19) induce effective immune responses, vaccination with booster doses is necessary because of waning immunity. We conducted an open-label, non-randomized, single-arm study in adults in Japan to assess the immunogenicity and safety of a single booster dose of the KD-414 purified whole-SARS-CoV-2-virion inactivated vaccine candidate after vaccination with a primary series of BNT162b2. The primary endpoint was serum neutralizing activity at 7 days after booster injection compared with the primary series of BNT162b2. The SARS-CoV-2-structural protein-binding antibody level and T cell response against SARS-CoV-2-Spike (S) peptides were also examined as secondary endpoints, and safety profile assessments were conducted. Twenty subjects who participated in a previous study declined an injection of KD-414 (non-KD-414 group) and received a booster dose of BNT162b2 instead. The non-KD-414 group was compared to the KD-414 group as a secondary outcome. A single dose of KD-414 induced lower serum neutralizing activity against the wild-type virus within 7 days compared to after the primary series of BNT162b2 but significantly induced anti-SARS-CoV-2-S1-receptor-binding domain-binding immunoglobulin G (IgG) antibodies and SARS-CoV-2-S peptide-specific CD4+ and CD8+ T cell responses. Local or systemic symptoms were significantly lower in the participants who received KD-414 than in those who received BNT162b2 as the third COVID-19 vaccine dose. The present data indicate that a single booster dose of KD-414 induces a substantial immune response in BNT162b2-primed individuals and has a good safety profile, thereby supporting further clinical trials to identify rational targets.

DOI： 10.1080/21645515.2023.2193074

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Publisher：医歯薬出版  

DOI： 10.32118/ayu28409726

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COVID-19 caused by SARS-CoV-2 has continually been serious threat to public health worldwide. While a few anti-SARS-CoV-2 therapeutics are currently available, their antiviral potency is not sufficient. Here, we identify two orally available 4-fluoro-benzothiazole-containing small molecules, TKB245 and TKB248, which specifically inhibit the enzymatic activity of main protease (Mpro) of SARS-CoV-2 and significantly more potently block the infectivity and replication of various SARS-CoV-2 strains than nirmatrelvir, molnupiravir, and ensitrelvir in cell-based assays employing various target cells. Both compounds also block the replication of Delta and Omicron variants in human-ACE2-knocked-in mice. Native mass spectrometric analysis reveals that both compounds bind to dimer Mpro, apparently promoting Mpro dimerization. X-ray crystallographic analysis shows that both compounds bind to Mpro's active-site cavity, forming a covalent bond with the catalytic amino acid Cys-145 with the 4-fluorine of the benzothiazole moiety pointed to solvent. The data suggest that TKB245 and TKB248 might serve as potential therapeutics for COVID-19 and shed light upon further optimization to develop more potent and safer anti-SARS-CoV-2 therapeutics.

DOI： 10.1038/s41467-023-36729-0

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Language：English  

DOI： 10.1016/j.jinf.2023.01.038

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Coronavirus disease 2019 (COVID-19) is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We evaluated the anti-SARS-CoV-2 antibody levels, anti-spike (S)-immunoglobulin G (IgG) and anti-nucleocapsid (N)-IgG, and the neutralization activity of IgG antibody in COVID‑19‑convalescent plasma against variants of SARS-CoV-2, alpha, beta, gamma, delta, kappa, omicron and R.1 strains. The study included 30 patients with clinically diagnosed COVID-19. The anti-S-IgG and anti-N-IgG levels ranged from 30.0 to 555.1 and from 10.1 to 752.6, respectively. The neutralization activity (50% inhibition concentration: IC50) for the wild-type Wuhan strain ranged from < 6.3 to 81.5 µg/ml. IgG antibodies were > 100 µg/ml in 18 of 30 (60%) subjects infected with the beta variant. The IC50 values for wild-type and beta variants correlated inversely with anti-S-IgG levels (p < 0.05), but no such correlation was noted with anti-N-IgG. IgG antibodies prevented infectivity and cytopathic effects of six different variants of concern in the cell-based assays of wild-type, alpha, gamma, delta, kappa and R.1 strains, but not that of the beta and omicron strains. IgG is considered the main neutralizing activity in the blood, although other factors may be important in other body tissues.

DOI： 10.1038/s41598-023-28591-3

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BACKGROUND: Data on the role of immunogenicity following the third vaccine dose against Omicron infection and COVID-19-compatible symptoms of infection are limited. METHODS: First we examined vaccine effectiveness (VE) of the third-dose against the second dose during the Omicron wave among the staff at a tertiary hospital in Tokyo. In a case-control study of third vaccine recipients, we compared the pre-infection live-virus neutralizing antibodies (NAb) against Omicron between breakthrough cases and their controls, who had close contact with COVID-19 patients. Among these cases, we examined the association between NAb levels and the number of COVID-19-compatible symptoms. RESULTS: Among the 1456 participants for VE analysis, 60 breakthrough infections occurred during the Omicron wave. The third-dose VE for infection was 54.6%. Among the third-dose recipients, NAb levels against Omicron did not differ between the cases (n=22) and controls (n=21). Among the cases, those who experienced COVID-19-compatible symptoms had lower NAb levels against Omicron than those who did not. CONCLUSIONS: The third vaccine dose was effective in decreasing the risk of SARS-CoV-2 infection during Omicron wave compared with the second dose. Among third-dose recipients, higher pre-infection NAb levels may not be associated with a lower risk of Omicron infection. Contrarily, they may be associated with fewer symptoms of infection.

DOI： 10.1016/j.ijid.2023.01.023

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

DOI： 10.1016/j.bbrc.2022.12.024

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Language：English   Publisher：エルゼビア・ジャパン(株)  

2021年5月～2021年8月に第1回目のワクチン接種を受け、その後に新型コロナウイルス感染症を発症した患者9名を対象に、抗新型コロナウイルス(SARS-CoV-2)結合抗体価と中和活性について後向き観察研究で調査した。調査項目は患者背景(年齢・性別、背景状態と併発状態、ワクチン型と接種時期、試料収集時期、ウイルス株、転帰)と臨床分離SARS-CoV-2株に対する血清の中和活性、および抗SARS-CoV-2結合抗体(S-IgG、S-IgM、N-IgG)量とした。その結果、SARS-CoV-2結合抗体と中和活性は、第1回目試料収集(中央値はワクチン接種後13.5日)から第2回目にかけて大幅に増加していた。

Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

DOI： 10.1016/j.transci.2022.103638

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Language：English   Publisher：シュプリンガー・ジャパン(株)  

症例は62歳男性で、2型糖尿病と末期腎不全のため5年間にわたり維持血液透析を行っており、C型肝炎とステージ2肝細胞癌のため他院で治療を受けていたが、無症候性のCOVID-19が判明したため当院に入院となった。在院期間を通じて症状は認められず、翌月に退院した。その数ヵ月後、家族の感染が判明して濃厚接触者となり、発熱、咳嗽などの症状が出現し、COVID-19と診断、入院となった。その後、呼吸不全をきたし、高度専門医療機関へ搬送転院となった。酸素吸入、ファビピラビル、ステロイドにより回復し、退院した。抗SARS-CoV-2抗体産生のキネティクスを評価するため、SARS-CoV-2スパイクタンパク質S1サブユニットに対するIgG抗体(IgG-S1)、full-lengthスパイクタンパク質に対するIgG抗体(anti-Spike IgG)、中和抗体を測定した。その結果、初回感染後5日目までセロコンバージョンを認めなかったのに対し、再感染後は10日目にIgG-S1のセロコンバージョンを認めた。同様にanti-Spike IgGおよび中和抗体は再感染後12日目から増加を示した。

Language：Japanese   Publisher：(一社)日本エイズ学会  

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Secretory immunoglobulin A (IgA) plays a crucial role in mucosal immunity for preventing the invasion of exogenous antigens; however, little is understood about the neutralizing activity of serum IgA. Here, to examine the role of IgA antibodies against COVID-19 illnesses, we determined the neutralizing activity of serum/plasma IgG and IgA purified from previously SARS-CoV-2-infected and COVID-19 mRNA vaccine-receiving individuals. We found that serum/plasma IgA possesses substantial but rather modest neutralizing activity against SARS-CoV-2 compared to IgG with no significant correlation with the disease severity. Neutralizing IgA and IgG antibodies achieved the greatest activity at approximately 25 and 35 days after symptom onset, respectively. However, neutralizing IgA activity quickly diminished to below the detection limit approximately 70 days after onset, while substantial IgG activity was observed until 200 days after onset. The total neutralizing activity in sera/plasmas of those with COVID-19 largely correlated with those in purified IgG and purified IgA and levels of anti-SARS-CoV-2-S1-binding IgG and anti-SARS-CoV-2-S1-binding IgA. In individuals who were previously infected with SARS-CoV-2 but had no detectable neutralizing IgA activity, a single dose of BNT162b2 or mRNA-1273 elicited potent serum/plasma-neutralizing IgA activity, but the second dose did not further strengthen the neutralization antibody response. The present data show that the systemic immune stimulation with natural infection and COVID-19 mRNA-vaccines elicits both SARS-CoV-2-specific neutralizing IgG and IgA responses in serum, but the IgA response is modest and diminishes faster than the IgG response. IMPORTANCE Secretory dimeric immunoglobulin A (IgA) plays an important role in preventing the invasion of foreign objects by its neutralizing activity on mucosal surfaces, while monomeric serum IgA is thought to relate to the phagocytic immune system activation. Here, we report that individuals with the novel coronavirus disease (COVID-19) developed both systemic neutralizing IgG (nIgG) and IgA (nIgA) active against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Although the nIgA response was quick and reached the highest activity earlier than the nIgG response, nIgA activity was modest and diminished faster than nIgG activity. In individuals who recovered from COVID-19 but had no detectable nIgA activity, a single dose of COVID-19 mRNA vaccine elicited potent nIgA activity, but the second dose did not further strengthen the antibody response. Our study provides novel insights into the role and the kinetics of serum nIgA against the pathogen in both naturally infected and COVID-19 mRNA vaccine-receiving COVID-19-convalescent individuals.

DOI： 10.1128/spectrum.02716-22

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：The Pharmaceutical Society of Japan  

<p>Dihydroceramide Δ4-desaturase 1 (DEGS1) enzymatic activity is inhibited with <i>N</i>-(4-hydroxyphenyl)-retinamide (4-HPR). We reported previously that 4-HPR suppresses severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) entry through a DEGS1-independent mechanism. However, it remains unclear whether DEGS1 is involved in other SARS-CoV-2 infection processes, such as virus replication and release. Here we established DEGS1 knockout (KO) in VeroE6^TMPRSS2 cells. No significant difference was observed in virus production in the culture supernatant between wild-type (WT) cells and DEGS1-KO cells, although the levels of dihydroceramide (DHCer), a DEGS1 substrate, were significantly higher in DEGS1-KO cells than WT cells. Furthermore, the virus-induced cytopathic effect was also observed in DEGS1-KO cells. Importantly, the EC₅₀ value of 4-HPR in DEGS1-KO cells was almost identical to the value reported previously in WT cells. Our results indicated the lack of involvement of DEGS1 in SARS-CoV-2 infection.</p>

DOI： 10.1248/bpb.b22-00503

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Language：English   Publisher：(公社)日本薬学会  

VeroE6/TMPRSS2細胞からジヒドロセラミドΔ4-デサチュラーゼ1(DEGS1)をノックアウトした細胞(DEGS1-KO細胞)を樹立し、SARS-CoV-2感染への影響を調べた。DEGS1の基質であるジヒドロセラミド(DHCer)のレベルは野生型(WT)よりDEGS1-KO細胞で有意に高かったが、培養上清中のウイルス産生量に有意差はなかった。DEGS1-KO細胞でもWT細胞と同様にウイルスによる細胞変性効果がみられた。ウイルス感染による細胞毒性に対する4-HPRの抑制作用のEC50値は、WT細胞とDEGS1-KO細胞の間で差がみられなかった。以上の結果から、SARS-CoV-2感染にDEGS1は関与しないと考えられた。

Language：English   Publisher：Scientific Reports  

The humoral and cellular immune responses against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) upon the coronavirus disease 2019 (COVID-19) vaccination remain to be clarified. Hence, we aimed to investigate the long-term chronological changes in SARS-CoV-2 specific IgG antibody, neutralizing antibody, and T cell responses during and after receiving the BNT162b2 vaccine. We performed serological, neutralization, and T cell assays among 100 hospital workers aged 22–73 years who received the vaccine. We conducted seven surveys up to 8 months after the second vaccination dose. SARS-CoV-2 spike protein-specific IgG (IgG-S) titers and T cell responses increased significantly following the first vaccination dose. The highest titers were observed on day 29 and decreased gradually until the end of the follow-up period. There was no correlation between IgG-S and T cell responses. Notably, T cell responses were detected on day 15, earlier than the onset of neutralizing activity. This study demonstrated that both IgG-S and T cell responses were detected before acquiring sufficient levels of SARS-CoV-2 neutralizing antibodies. These immune responses are sustained for approximately 6 to 10 weeks but not for 7 months or later following the second vaccination, indicating the need for the booster dose (i.e., third vaccination).

DOI： 10.1038/s41598-022-19581-y

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Vaccines for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have shown high efficacy in preventing the onset of disease. However, the immune response to infection immediately after the first vaccination remains unknown. We examined the anti-SARS-CoV-2-binding-antibody titers and neutralizing activity in patients who developed coronavirus disease 2019 after the first vaccination. The anti-SARS-CoV-2-binding-antibody titers and neutralizing activity drastically increased from the first to the second collection. Our results may provide important data on the course of immune response following vaccination.

DOI： 10.1016/j.jiac.2022.08.026

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Language：Japanese   Publisher：Respirology Case Reports  

Mediastinal neurogenic tumours are mostly derived from sympathetic nerves and intercostal nerves, and vagus nerve-derived schwannomas are rare. We encountered a tumour originating from the origin of the recurrent laryngeal nerve that was accompanied by the azygos lobe, which made it difficult to approach; it was ultimately able to be removed via uniportal video-assisted thoracic surgery. This case involved a 63-year-old female patient. There were no particular symptoms, but an abnormal chest shadow was noted on an imaging examination. Chest imaging revealed a smooth-surfaced mass in the upper right mediastinum with the azygos lobe. A diagnosis of schwannoma was made by imaging, and the patient underwent resection via uniportal video-assisted thoracic surgery. The tumour, which originated from the origin of the right recurrent laryngeal nerve, was sharply removed without causing recurrent laryngeal nerve palsy.

DOI： 10.1002/rcr2.1023

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Language：English   Publishing type：Research paper (scientific journal)  

In the present prospective study, 225 individuals in Kumamoto General Hospital, Japan, who received two-doses of BNT162b2 vaccine were enrolled/followed up over 150 days and neutralizing activity (NT50) of their sera and antiviral activity (EC50) of IgG purified from sera on day-60 post-1st-dose were determined against wild-type SARS-CoV-2 (SARS-CoV-2Wuhan) (n = 211) and 9 variants (Alpha, Beta, Gamma, Delta, and Kappa) (n = 45). Time-dependent changes of IgG-activity (n = 25) against SARS-CoV-2Wuhan and variants were also examined. Day-60 sera showed reduced NT50 by more than 50% against all variants examined, and greatest reduction was seen with Beta. IgG fractions of high-responders and moderate-responders showed similar fold-changes in EC50 against each variant compared to SARS-CoV-2Wuhan. Evaluation of EC50 of IgG obtained at different time-points (day-28 to -150) revealed time-dependent reduction of activity against all variants. However, against Delta, relatively long-lasting favorable antiviral activity (at least 150 days) was observed. Our data strongly suggest that the successful antecedent scale-up of mRNA-based vaccine administrations in Japan was the primary contributor to the lessening of the otherwise more devastating SARS-CoV-2 pandemic wave caused by the Delta variant. The present data that the effectiveness of vaccine against the then-dominant SARS-CoV-2 variant was likely associated with the moderation of the COVID-19 pandemic wave suggest that as in the case of influenza vaccines, the development of multivalent mRNA-based vaccines represent a generalizable approach to pre-emptively respond pandemic with mutable pathogens.

DOI： 10.1038/s41598-022-17071-9

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Language：English   Publisher：(国研)国立国際医療研究センター  

回復期血漿療法は重篤なCOVID-19患者に対する重要な治療法なので、その安全性を確認する試験を行った。高い抗SARS-CoV-2スパイクIgG価と強い中和活性を持つCOVID-19患者から血液を採取し、当院で保存した。回復期血漿を、入院後3日以内に酸素吸入を必要とする重篤なCOVID-19患者11名に投与した。1名は輸血後3時間以内に静注部位の周囲の皮膚に、発赤のような有害事象を経験した。10名は28日以内に臨床的に改善したが、1名は血漿療法と無関係の原因で死亡した。本研究のCOVID-19患者は厳しい有害事象なしに回復期血漿を受け入れたことを示唆していた。

Language：English   Publishing type：Research paper (scientific journal)  

Management of COVID-19 patients with humoral immunodeficiency is challenging. We describe a woman with COVID-19 with multiple relapses due to anti-CD20 monoclonal antibody treatment. She was successfully treated with casirivimab/imdevimab and confirmed to have neutralizing antibodies. This case suggests that monoclonal antibodies have therapeutic and prophylactic value in patients with humoral immunodeficiency.

DOI： 10.1016/j.jiac.2022.03.002

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Language：English   Publisher：エルゼビア・ジャパン(株)  

症例は58歳女性で、濾胞性リンパ腫の再発予防のため、2ヵ月ごとにリツキシマブを6ヵ月間投与されていた。リツキシマブ投与2日後に咳と咽頭痛が出現し、発症4日後にSARS-CoV-2陽性となり、他院に入院したが、入院後6日目に症状は自然に改善し、退院した。退院後8日目に咳嗽と発熱が再発した。再入院し、レムデシビル投与を5日間とデキサメタゾン6mg/日投与を受けた。発熱は急速に回復したが、再入院16日目にデキサメタゾンからプレドニゾロン10mg/日へ変更したところ再燃した。低酸素血症を発症し、胸部CTスキャンで肺浸潤が確認された。バリシティニブ4mg/日投与が開始され、デキサメタゾン6mg/日への変更とレムデシビル5日間投与が行われた。入院後55日目にCOVID-19治療が奏効しないため当院へ転院した。デキサメタゾン6mg/日の経口投与を継続した。レムデシビルを5日間投与し、入院6日目に中和モノクローナル抗体カシリビマブ/イムデビマブを投与し、経過を観察した。8日目に低酸素血症が改善し、12日目と13日目にSARS-CoV-2陰性化を確認し、16日目に退院した。副腎皮質ステロイドは1ヵ月かけて漸減し、発熱や呼吸困難の再発はなかった。退院後37日目の胸部CT所見では、浸潤はほぼ消失していた。

Language：English   Publishing type：Research paper (scientific journal)   Publisher：MDPI AG  

Background: The coronavirus disease 2019 (COVID-19) pandemic is currently ongoing, and there have been significant efforts in the development of COVID-19 vaccines. However, the neutralizing antibody titers in vaccinated individuals are reported to progressively decrease over time. Japanese pharmaceutical companies have published the results of Phase I and II studies on the safety and efficacy of different vaccines. Final clinical trials will be conducted with the aim of practical application by March 2023. To effectively utilize vaccines developed by Japanese companies, the efficacy and safety of a booster dose (i.e., third vaccination) must be evaluated among individuals who have received three doses of different vaccines. Methods: This protocol describes a study that aims to examine the effect of a booster dose of “KD-414”, a novel Japanese inactivated vaccine, on antibody titers among participants involved in a previous study. Volunteers in this protocol will be recruited from participants in the previous study and immunized with KD-414 after obtaining consent. The antibody titers, before and after immunization with KD-414, among participants who previously received two doses of the BNT162b2 mRNA vaccine, will be comparatively analyzed. Discussion: The reactogenicity and immunogenicity of seven different COVID-19 vaccines including an inactivated vaccine as a third dose after two doses of ChAdOx1 nCov-19 or BNT162b2, has been tested previously, and found to be superior to control (quadrivalent meningococcal conjugate vaccine) regardless of which vaccine had been received during the initial course. This suggests that many types of third booster doses are efficacious. It is anticipated that this study will provide evidence of the safety and immunogenicity of KD-414 as a booster vaccine, which will have profound public health implications.

DOI： 10.3390/life12070966

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Secretory immunoglobulin A (IgA) plays a crucial role in the mucosal immunity for preventing the invasion of the exogenous antigens, however, little has been understood about the neutralizing activity of serum IgA. Here, to examine the role of IgA antibodies against COVID-19 illnesses, we determined the neutralizing activity of serum/plasma IgG and IgA purified from previously SARS-CoV-2-infected and COVID-19 mRNA-vaccine-receiving individuals. We found that serum/plasma IgA possesses substantial but rather modest neutralizing activity against SARS-CoV-2 compared to IgG with no significant correlation with the disease severity. Neutralizing IgA and IgG antibodies achieved the greatest activity at approximately 25 and 35 days after symptom onset, respectively. However, neutralizing IgA activity quickly diminished and went down below the detection limit approximately 70 days after onset, while substantial IgG activity was observed till 200 days after onset. The total neutralizing activity in sera/plasmas of those with COVID-19 largely correlated with that in purified-IgG and purified-IgA and levels of anti-SARS-CoV-2-S1-binding IgG and anti-SARS-CoV-2-S1-binding IgA. In individuals who were previously infected with SARS-CoV-2 but had no detectable neutralizing IgA activity, a single dose of BNT162b2 or mRNA-1273 elicited potent serum/plasma neutralizing IgA activity but the second dose did not further strengthen the neutralization antibody response. The present data show that the systemic immune stimulation with natural infection and COVID-19 mRNA-vaccines elicit both SARS-CoV-2-specific neutralizing IgG and IgA response in serum, but the IgA response is modest and diminishes faster compared to IgG response. Author Summary: Immunoglobulin A (IgA) is the most abundant type of antibody in the body mostly located on mucosal surfaces as a dimeric secretory IgA. Such secretory IgA plays an important role in preventing the adherence and invasions of foreign objects by its neutralizing activity, while monomeric serum IgA is thought to relate to the phagocytic immune system activation. Here, we report that individuals with the novel coronavirus disease (COVID-19) developed both systemic neutralizing IgG and IgA active against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Although the neutralizing IgA response was quick and reached the highest activity 25 days post-symptom-onset, compared to 35 days for IgG response, neutralizing IgA activity was modest and diminished faster than neutralizing IgG response. In individuals, who recovered from COVID-19 but had no detectable neutralizing IgA activity, a single dose of COVID-19 mRNA-vaccine elicited potent neutralizing IgA activity but the second dose did not further strengthen the antibody response. Our study provides novel insights into the role and the kinetics of serum IgA against the viral pathogen both in naturally-infected and COVID-19 mRNA-vaccine-receiving COVID-19-convalescent individuals.

DOI： 10.1101/2022.06.09.495422

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Language：English   Publishing type：Research paper (scientific journal)  

BACKGROUND: Coronavirus disease 2019 is a global public health concern. As of December 2020, the therapeutic agents approved for coronavirus disease 2019 in Japan were limited to two drugs: remdesivir, an antiviral drug, granted a Special Approval for Emergency on 7 May 2020, and dexamethasone, which has an anti-inflammatory effect. The aim of this study is to evaluate the efficacy of convalescent plasma collected from donors who recovered from coronavirus disease 2019. METHODS: This is an open-label, randomized controlled trial comprising two groups: a convalescent plasma and a standard-of-care group. Plasma administered to patients with coronavirus disease 2019 randomized in the convalescent plasma group of this trial will be plasma that has been collected and stored in an associated study. Patients with a diagnosis of mild coronavirus disease 2019 will be included in this trial. The efficacy of convalescent plasma transfusion will be evaluated by comparing the convalescent plasma group to the standard-of-care group (without convalescent plasma transfusion) with respect to changes in the viral load and other measures. The primary endpoint will be time-weighted average changes in the SARS-CoV-2 virus load in nasopharyngeal swabs from day 0 to days 3 and 5. It is hypothesized that the intervention should result in a decrease in the viral load in the convalescent plasma group until day 5. This endpoint has been used as a change in viral load has and been used as an index of therapeutic effect in several previous studies. DISCUSSION: The proposed trial has the potential to prevent patients with mild COVID-19 from developing a more severe illness. Several RCTs of convalescent plasma therapy have already been conducted in countries outside of Japan, but no conclusion has been reached with respect to the efficacy of convalescent plasma therapy, which is likely in part because of the heterogeneity of the types of target patients, interventions, and endpoints among trials. Actually, previous clinical trials on plasma therapy have shown inconsistent efficacy and are sometimes ineffective in COVID-19 patients with severe disease, which is due to unmeasured neutralizing antibody titer in the COVID-19 convalescent plasma. To improve this issue, in this study, we measure neutralizing activity of convalescent plasma before administration and provide the plasma with high neutralizing activity to the subjects. It is hoped that this study will further evidence to support the role of convalescent plasma therapy in COVID-19.

DOI： 10.3390/life12060856

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Language：English  

We present a case of a 58-year-old Japanese man with a history of 2 previous COVID-19 infections, who received 2 doses of mRNA-1273 vaccine. We are not aware of any previous study regarding antibody tendency after 2 infections and 2 vaccinations. We evaluated his IgG titer of antispike protein and neutralizing activity from the first infection before and after 2 doses of vaccine. Both antispike IgG titer and neutralizing activity showed a tendency to decline almost 1 year after initial infection; they rapidly increased after the first vaccination, and they remained high after the second vaccination. Although this is a single case report, it seems to have generalizability because the findings are consistent with previous reports regarding single infections or 3 doses of vaccination. Our findings suggest that a single booster shot may provide sufficient protection and aid the understanding of immunologic responses of vaccination in patients with COVID-19 with history of re-infection.

DOI： 10.1016/j.ijid.2022.03.017

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1093/infdis/jiac209

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Language：English   Publishing type：Research paper (scientific journal)  

The recent emergence of SARS-CoV-2 Omicron variants possessing numerous mutations has raised concerns of decreased effectiveness of current vaccines, therapeutic monoclonal antibodies, and antiviral drugs for COVID-19 against these variants1,2. The original Omicron lineage, BA.1, prevailed in many countries, but more recently, BA.2 has become dominant in at least 68 countries3. Here, we evaluated the replicative ability and pathogenicity of authentic infectious BA.2 isolates in immunocompetent and human ACE2 (hACE2)-expressing mice and hamsters. In contrast to recent data with chimeric, recombinant SARS-CoV-2 strains expressing the spike proteins of BA.1 and BA.2 on an ancestral WK-521 backbone4, we observed similar infectivity and pathogenicity in mice and hamsters between BA.2 and BA.1, and less pathogenicity compared to early SARS-CoV-2 strains. We also observed a marked and significant reduction in the neutralizing activity of plasma from COVID-19 convalescent individuals and vaccine recipients against BA.2 compared to ancestral and Delta variant strains. In addition, we found that some therapeutic monoclonal antibodies (REGN10987/REGN10933, COV2-2196/COV2-2130, and S309) and antiviral drugs (molnupiravir, nirmatrelvir, and S-217622) can restrict viral infection in the respiratory organs of BA.2-infected hamsters. These findings suggest that the replication and pathogenicity of BA.2 is comparable to that of BA.1 in rodents and that several therapeutic monoclonal antibodies and antiviral compounds are effective against Omicron/BA.2 variants.

DOI： 10.1038/s41586-022-04856-1

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Although messenger ribonucleic acid vaccines are substantially effective toward SARS-CoV-2 infection, patients with hematologic malignancies are still prone to the virus. Herein, we report a fatal case of breakthrough SARS-CoV-2 Delta variant infection in a patient with mucosa-associated lymphoid tissue lymphoma with remission by bendamustine-rituximab (BR) therapy completed a year ago. The serologic study revealed impaired responsiveness toward vaccines and prolonged high viral load after infection. BR therapy seemingly induced an immune escape. Prevention and treatment strategies for such vulnerable patients should be clarified immediately.

DOI： 10.1016/j.ijid.2022.04.058

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DOI： 10.1056/NEJMc2201933

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Language：English   Publishing type：Research paper (scientific journal)  

BNT162b2, an mRNA-based SARS-CoV-2 vaccine (Pfizer-BioNTech, New York, NY, USA), is one of the most effective COVID-19 vaccines and has been approved by more than 130 countries worldwide. However, several studies have reported that the COVID-19 vaccine shows high interpersonal variability in terms of humoral and cellular responses, such as those with respect to SARS-CoV-2 spike protein immunoglobulin (Ig)G, IgA, IgM, neutralizing antibodies, and CD4+ and CD8+ T cells. The objective of this study is to investigate the kinetic changes in anti-SARS-CoV-2 spike IgG (IgG-S) profiles and adverse reactions and their associations with HLA profiles (HLA-A, -C, -B, -DRB1, -DQA1, -DQB1, -DPA1 and -DPB1) among 100 hospital workers from the Center Hospital of the National Center for Global Health and Medicine (NCGM), Tokyo, Japan. DQA1*03:03:01 (p = 0.017; Odd ratio (OR) 2.80, 95%confidence interval (CI) 1.05-7.25) was significantly associated with higher IgG-S production after two doses of BNT162b2, while DQB1*06:01:01:01 (p = 0.028, OR 0.27, 95%CI 0.05-0.94) was significantly associated with IgG-S declines after two doses of BNT162b2. No HLA alleles were significantly associated with either local symptoms or fever. However, C*12:02:02 (p = 0.058; OR 0.42, 95%CI 0.15-1.16), B*52:01:01 (p = 0.031; OR 0.38, 95%CI 0.14-1.03), DQA1*03:02:01 (p = 0.028; OR 0.39, 95%CI 0.15-1.00) and DPB1*02:01:02 (p = 0.024; OR 0.45, 95%CI 0.21-0.97) appeared significantly associated with protection against systemic symptoms after two doses of BNT162b2 vaccination. Further studies with larger sample sizes are clearly warranted to determine HLA allele associations with the production and long-term sustainability of IgG-S after COVID-19 vaccination.

DOI： 10.3390/vaccines10040563

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Language：English   Publishing type：Research paper (scientific journal)  

High vaccine reactogenicities may reflect stronger immune responses, but the epidemiological evidence for coronavirus disease 2019 (COVID-19) vaccines is sparse and inconsistent. We observed that a fever of ≥38℃ after two doses of the BNT162b2 vaccine was associated with higher severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike IgG titers.

DOI： 10.1016/j.vaccine.2022.02.052

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DOI： 10.1056/NEJMc2119407

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Language：English   Publishing type：Research paper (scientific journal)  

Hemodialysis patients are vulnerable to severe and lethal COVID-19, and their protective immunity against COVID-19 is not yet fully understood. Therefore, we report a case of COVID-19 reinfection in a hemodialysis patient 81 days after the first episode and discuss the role of antibodies in SARS-CoV-2 infection. A hemodialysis patient developed asymptomatic COVID-19 due to an outbreak in a hospital on October 29th, 2020. As he was hospitalized and did not develop any symptoms, he was discharged on November 9th. On January 18th, he presented with symptomatic COVID-19 due to close household contact. Then, he developed respiratory failure and was transferred to National Center for Global Health and Medicine if he would need intensive care. He recovered with oxygen inhalation, favipiravir, and steroid treatment, and was discharged on February 12th. To evaluate anti-SARS-CoV-2 antibodies during two hospital stays, we measured immunoglobulin (Ig) G specific for S1 subunit of Spike (S) protein of SARS-CoV-2 (IgG-S1) , IgG specific for the full-length S protein (anti-Spike IgG) and neutralizing antibodies. No seroconversion occurred 5 days after initial infection, the seroconversion of IgG-S1 was observed 10 days after the second infection. Similar to IgG-S1 antibody titer results, anti-Spike IgG and neutralizing antibodies increased from 12 days after the second infection. In conclusion, we experienced a case of COVID-19 reinfection in a hemodialysis patient 81 days after the first episode and showed the kinetics and role of antibodies in SARS-CoV-2 infection. Further studies are needed to understand SARS-CoV-2 reinfection risk in hemodialysis patients and its clinical significance.

DOI： 10.1007/s13730-022-00697-z

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Publishing type：Research paper (scientific journal)  

DOI： 10.21203/rs.3.rs-1463966/v1

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The recent emergence of SARS-CoV-2 Omicron variants possessing large numbers of mutations has raised concerns of decreased effectiveness of current vaccines, therapeutic monoclonal antibodies, and antiviral drugs for COVID-19 against these variants1,2. While the original Omicron lineage, BA.1, has become dominant in many countries, BA.2 has been detected in at least 67 countries and has become dominant in the Philippines, India, and Denmark. Here, we evaluated the replicative ability and pathogenicity of an authentic infectious BA.2 isolate in immunocompetent and human ACE2 (hACE2)-expressing mice and hamsters. In contrast to recent data with chimeric, recombinant SARS-CoV-2 strains expressing the spike proteins of BA.1 and BA.2 on an ancestral WK-521 backbone3, we observed similar infectivity and pathogenicity in mice and hamsters between BA.2 and BA.1, and less pathogenicity compared to early SARS-CoV-2 strains. We also observed a marked and significant reduction in the neutralizing activity of plasma from COVID-19 convalescent individuals and vaccine recipients against BA.2 compared to ancestral and Delta variant strains. In addition, we found that some therapeutic monoclonal antibodies (REGN10987/REGN10933, COV2-2196/COV2-2130, and S309) and antiviral drugs (molnupiravir, nirmatrelvir, and S-217622) can restrict viral infection in the respiratory organs of hamsters infected with BA.2. These findings suggest that the replication and pathogenicity of BA.2 is comparable to that of BA.1 in rodents and that several therapeutic monoclonal antibodies and antiviral compounds are effective against Omicron/BA.2 variants.

DOI： 10.21203/rs.3.rs-1375091/v1

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Language：English   Publishing type：Research paper (scientific journal)  

Despite various attempts to treat severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-infected patients with COVID-19 convalescent plasmas, neither appropriate approach nor clinical utility has been established. We examined the efficacy of administration of highly neutralizing COVID-19 convalescent plasma (hn-plasmas) and such plasma-derived IgG administration using the Syrian hamster COVID-19 model. Two hn-plasmas, which were in the best 1% of 340 neutralizing activity-determined convalescent plasmas, were intraperitoneally administered to SARS-CoV-2-infected hamsters, resulting in a significant reduction of viral titers in lungs by up to 32-fold compared to the viral titers in hamsters receiving control nonneutralizing plasma, while with two moderately neutralizing plasmas (mn-plasmas) administered, viral titer reduction was by up to 6-fold. IgG fractions purified from the two hn-plasmas also reduced viral titers in lungs more than those from the two mn-plasmas. The severity of lung lesions seen in hamsters receiving hn-plasmas was minimal to moderate as assessed using microcomputerized tomography, which histological examination confirmed. Western blotting revealed that all four COVID-19 convalescent plasmas variably contained antibodies against SARS-CoV-2 components, including the receptor-binding domain and S1 domain. The present data strongly suggest that administering potent neutralizing activity-confirmed COVID-19 convalescent plasmas would be efficacious in treating patients with COVID-19. IMPORTANCE Convalescent plasmas obtained from patients who recovered from a specific infection have been used as agents to treat other patients infected with the very pathogen. To treat using convalescent plasmas, despite that more than 10 randomized controlled clinical trials have been conducted and more than 100 studies are currently ongoing, the effects of convalescent plasma against COVID-19 remained uncertain. On the other hand, certain COVID-19 vaccines have been shown to reduce the clinical COVID-19 onset by 94 to 95%, for which the elicited SARS-CoV-2-neutralizing antibodies are apparently directly responsible. Here, we demonstrate that highly neutralizing effect-confirmed convalescent plasmas significantly reduce the viral titers in the lung of SARS-CoV-2-infected Syrian hamsters and block the development of virally induced lung lesions. The present data provide a proof of concept that the presence of highly neutralizing antibody in COVID-19 convalescent plasmas is directly responsible for the reduction of viral replication and support the use of highly neutralizing antibody-containing plasmas in COVID-19 therapy with convalescent plasmas.

DOI： 10.1128/JVI.01551-21

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Publishing type：Research paper (scientific journal)   Publisher：National Center for Global Health and Medicine (JST)  

DOI： 10.35772/ghmo.2022.01002

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Language：English   Publishing type：Research paper (scientific journal)  

BACKGROUND: While increasing coverage of effective vaccines against coronavirus disease 2019 (COVID-19), emergent variants raise concerns about breakthrough infection. Data are limited, however, whether breakthrough infection during the epidemic of the variant is ascribed to insufficient vaccine-induced immunogenicity. METHODS: We described incident COVID-19 in relation to the vaccination program among workers of a referral hospital in Tokyo. During the predominantly Delta epidemic, we followed 2,415 fully vaccinated staff (BNT162b2) for breakthrough infection and selected three matched controls. We measured post-vaccination neutralizing antibodies against the wild-type, Alpha (B.1.1.7), and Delta (B.1.617.2) strains using live viruses and anti-spike antibodies using quantitative assays, and compared them using the generalized estimating equation model between the two groups. RESULTS: No COVID-19 cases occurred 1-2 months after the vaccination program during the fourth epidemic wave in Japan, dominated by the Alpha variant, while 22 cases emerged 2-4 months after the vaccination program during the fifth wave, dominated by the Delta variant. In the vaccinated cohort, all 17 cases of breakthrough infection were mild or asymptomatic and had returned to work early. There was no measurable difference between cases and controls in post-vaccination neutralizing antibody titers against the wild-type, Alpha, and Delta, and anti-spike antibody titers, while neutralizing titers against the variants were considerably lower than those against the wild-type. CONCLUSIONS: Post-vaccination neutralizing antibody titers were not decreased among patients with breakthrough infection relative to their controls under the Delta variant rampage. The result points to the importance of infection control measures in the post-vaccination era, irrespective of immunogenicity profile.

DOI： 10.1093/cid/ciab1048

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DOI： 10.1016/j.crmeth.2021.100122

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Authorship：Last author,　Corresponding author  

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While mRNA vaccines against SARS-CoV-2 are exceedingly effective in preventing symptomatic infection, their immune response features remain to be clarified. In the present prospective study, 225 healthy individuals in Japan, who received two BNT162b2 doses, were enrolled. Correlates of BNT162b2-elicited SARS-CoV-2-neutralizing activity (50% neutralization titer: NT50; assessed using infectious virions) with various determinants were examined and the potency of sera against variants of concerns was determined. Significant rise in NT50s was seen in sera on day 28 post-1st dose. A moderate inverse correlation was seen between NT50s and ages, but no correlation seen between NT50s and adverse effects. NT50s and SARS-CoV-2-S1-binding-IgG levels on day 28 post-1st dose and pain scores following the 2nd dose were greater in women than in men. The average half-life of NT50s was ~ 68 days, and 23.6% (49 out of 208 individuals) failed to show detectable neutralizing activity on day 150. While sera from elite-responders (NT50s > 1,500: the top 4% among the participants) potently to moderately blocked all variants of concerns examined, some sera with low NT50s failed to block the B.1.351-beta strain. Since BNT162b2-elicited immunity against SARS-CoV-2 is short, an additional vaccine or other protective measures are needed.

DOI： 10.1038/s41598-021-01930-y

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Publisher：Cold Spring Harbor Laboratory  

<bold>Background.</bold> The humoral and cellular immune responses against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) upon coronavirus disease 2019 (COVID-19) vaccination remain to be clarified. Hence, we aimed to investigate the chronological changes in SARS-CoV-2 specific IgG antibody, neutralizing antibody, and T cell responses during and after receiving the BNT162b2 vaccine.
<bold>Methods.</bold> We performed serological, neutralization, and T cell assays among 100 hospital workers aged 22-73 years who received the vaccine. We conducted five surveys on day 1, day 15, day 29 (seven days after the second dose), day 61, and days 82-96 following the first dose.
<bold>Results.</bold> SARS-CoV-2 spike protein-specific IgG (IgG-S) titers and T cell responses increased significantly following the first vaccination dose. The highest titers were observed on day 29 and decreased gradually until the end of the follow-up period. There was no correlation between IgG-S and T cell responses. Notably, T cell responses were detected on day 15, earlier than the onset of neutralizing activity.
<bold>Conclusions.</bold> This study demonstrated that both IgG-S and T cell responses were detected before acquiring sufficient levels of SARS-CoV-2 neutralizing antibodies. These early immune responses are sustained for approximately six-ten weeks following the second vaccination dose.

DOI： 10.1101/2021.11.06.21265632

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Language：English   Publisher：エルゼビア・ジャパン(株)  

SARS-CoV-2に対する化学発光酵素免疫測定法に基づく自動定量抗原検査法(QAT)の診断能の経時変化や感染性評価への寄与についての後方視的観察研究を実施した。COVID-19入院患者68名から鼻咽頭ぬぐい液100検体を採取した。51検体は初期(発症後10日以内)、49検体は後期(発症後10日以上)に得た。QATの感度と特異度は、それぞれ全期間で0.82(0.72〜0.90)と0.95(0.75〜0.99)、初期で0.93(0.82〜0.98)と1.00(0.39〜1.00)、後期で0.66(0.48〜0.82)と0.93(0.69〜0.99)であった。ROC解析により、初期検体と後期検体を区別する理想的なカットオフ値は6.93pg/mLであった。その新しいカットオフ値を用いた場合、後期を予測する感度、特異度、陽性的中率、陰性的中率はそれぞれ0.75(0.61〜0.86)、0.76(0.62〜0.87)、0.75(0.61〜0.86)、0.76(0.62〜0.87)であった。以上より、QATはCOVID-19の初期段階において良好な診断精度を有していた。また、適切なカットオフポイントを設定することで、非伝染性患者を迅速に特定できる可能性があった。

Language：English   Publishing type：Research paper (scientific journal)  

INTRODUCTION: The automated quantitative antigen test (QAT), which detects severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is suitable for mass screening. However, its diagnostic capability differentiated by time from onset and potential contribution to infectivity assessment have not been fully investigated. METHODS: A retrospective, observational study using nasopharyngeal swab specimens from coronavirus disease (COVID-19) inpatients was conducted using LumipulseⓇ SARS-CoV-2 antigen test. Diagnostic accuracy was examined for the early (up to 10 days after onset) and late (over 10 days after onset) stages. Time-course QAT changes and reverse-transcription quantitative polymerase chain reaction tests results were displayed as locally estimated scatterplot smoothing curve, and receiver operating characteristic curve (ROC) analysis was used to determine the appropriate cutoff value for differentiating the early and late stages. RESULTS: We obtained 100 specimens from 68 COVID-19 patients, including 51 early-stage and 49 late-stage specimens. QAT sensitivity and specificity were 0.82 (0.72-0.90) and 0.95 (0.75-0.99) for all periods, 0.93 (0.82-0.98) and 1.00 (0.39-1.00) for the early stage, and 0.66 (0.48-0.82) and 0.93 (0.69-0.99) for the late stage, respectively. The ROC analysis indicated an ideal cutoff value of 6.93 pg/mL for distinguishing early-from late-stage specimens. The sensitivity, specificity, positive predictive value, and negative predictive value for predicting the late stage were 0.76 (0.61-0.87), 0.76 (0.63-0.87), 0.76 (0.61-0.87), and 0.76 (0.63-0.87). CONCLUSIONS: QAT has favorable diagnostic accuracy in the early COVID-19 stages. In addition, an appropriate cutoff point can potentially facilitate rapid identification of noncontagious patients.

DOI： 10.1016/j.jiac.2021.08.015

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Publisher：Cold Spring Harbor Laboratory  

<title>Abstract</title><sec><title>Background</title>While increasing coverage of effective vaccines against coronavirus disease 2019 (COVID-19), emergent variants raise concerns about breakthrough infections. Data are limited, however, whether breakthrough infection during the epidemic of the variant is ascribed to insufficient vaccine-induced immunogenicity.

</sec><sec><title>Methods</title>We described incident COVID-19 in relation to the vaccination program among workers of a referral hospital in Tokyo. During the predominantly Delta epidemic, we followed 2,473 fully vaccinated staff (BNT162b2) for breakthrough infection and selected three matched controls. We measured pre-infection neutralizing antibodies against the wild-type, Alpha (B.1.1.7), and Delta (B.1.617.2) strains using live viruses and anti-spike antibodies using quantitative assays, and compared them using the generalized estimating equation model between the two groups.

</sec><sec><title>Results</title>No COVID-19 cases occurred 1–2 months after the vaccination program during the fourth epidemic wave in Japan, dominated by the Alpha variant, while 22 cases emerged 2–4 months after the vaccination program during the fifth wave, dominated by the Delta variant. In the vaccinated cohort, all 17 cases of breakthrough infection were mild or asymptomatic and had returned to work early. There was no measurable difference between cases and controls in pre-infection neutralizing antibody titers against the wild-type, Alpha, and Delta, and anti-spike antibody titers, while neutralizing titers against the variants were considerably lower than those against the wild-type.

</sec><sec><title>Conclusions</title>Pre-infection neutralizing antibody titers were not decreased among patients with breakthrough infection under the Delta variant rampage. The result points to the importance of infection control measures in the post-vaccination era, irrespective of immunogenicity profile.

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DOI： 10.1101/2021.10.20.21265301

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：American Society for Microbiology  

Sphingolipids could play an important role in SARS-CoV-2 S-mediated membrane fusion with host cells. We studied the cell-cell fusion using SARS-CoV-2 S-expressing cells and sphingolipid-manipulated target cells, with an inhibitor of the sphingolipid metabolism. 4-HPR (also known as fenretinide) is an inhibitor of DES1, and it exhibits antitumor activity and suppresses cell-cell fusion and viral infection. 4-HPR suppresses membrane fusion through a decrease in membrane fluidity, which could possibly be the cause for the inhibition of SARS-CoV-2 infection.

DOI： 10.1128/JVI.00807-21

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Language：English   Publisher：エルゼビア・ジャパン(株)  

新型コロナウイルス感染症患者21例を対象に、抗原迅速検査とウイルス培養の結果が相関するかどうかを検討した。対象は新型コロナウイルス感染症患者から採取した鼻腔スワブ検体26例で、そのうち25例は患者が発熱、咳嗽等の呼吸器症状、胸痛、味覚障害、嗅覚障害を発現している期間に採取したものであった。増幅に必要なサイクル数(CT値)を30以下としてリアルタイム定量PCR法を実施し、抗原迅速検査とウイルス培養を実施した。抗原迅速検査ではウイルス量が多いほど陽性率が高かったが、ウイルス培養では発症から10日以内で陽性率が高かった。抗原迅速検査の陽性20例のうち9例(45%)、陰性6例のうち1例(17%)から培養検査でウイルスが検出された。ウイルス量は抗原迅速検査とウイルス培養の結果と関連していた。ROC解析でウイルス量の最適カットオフ値を2.1×10^5copies/mLとした場合、抗原迅速検査の陽性を予測する感度は75%、特異度は100%であった。またウイルス量のカットオフ値を5.4×10^5copies/mLとした場合、ウイルス培養の陽性を予測する感度は90%、特異度は81%であった。

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

DOI： 10.1016/j.jinf.2021.05.017

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

Rapid antigen tests (RATs) for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have advantages over viral culture in terms of cost and rapidity of testing, but they have low sensitivity. In addition, RATs tend to be negative from approximately 11 days after symptom onset. To determine whether the antigen-negative state indicates a lack of infectiousness, we assessed the association between viral culture and RAT results. Viral culture, reverse transcription-quantitative polymerase chain reaction (RT-qPCR), and rapid antigen testing were performed on stored nasopharyngeal samples with threshold cycle values < 30, based on previous RT-qPCR testing. SARS-CoV-2 was isolated by viral culture from nine samples (45%) and one sample (17%) with positive and negative RAT results, respectively. The RAT and viral culture results were both associated with the viral load level and their cutoffs were similar, but the associations were not statistically significant. RAT might be a useful indicator of infectiousness, which can be helpful to control infection. However, further studies with larger sample size are warranted to confirm this observation.

DOI： 10.1016/j.jiac.2021.05.006

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Language：English  

DOI： 10.1016/j.ijid.2021.06.009

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

While mRNA vaccines against SARS-CoV-2 are exceedingly effective in preventing symptomatic infection, their immune response features remain to be clarified. In the present prospective study, 225 healthy individuals in Japan, who received two BNT162b2 doses, were enrolled. Correlates of BNT162b2-elicited SARS-CoV-2-neutralizing activity (50% neutralization titer: NT50; assessed using infectious virions) with various determinants were examined and the potency of sera against variants of concerns was determined. Significant rise in NT50s was seen in sera on day 28 post-1st dose. A moderate inverse correlation was seen between NT50s and ages, but no correlation seen between NT50s and adverse effects. NT50s and SARS-CoV-2-S1-binding-IgG levels on day 28 post-1st dose and pain scores following the 2nd dose were greater in women than in men. The average half-life of NT50s was ~ 68 days, and 23.6% (49 out of 208 individuals) failed to show detectable neutralizing activity on day 150. While sera from elite-responders (NT50s > 1,500: the top 4% among the participants) potently to moderately blocked all variants of concerns examined, some sera with low NT50s failed to block the B.1.351-beta strain. Since BNT162b2-elicited immunity against SARS-CoV-2 is short, an additional vaccine or other protective measures are needed.

DOI： 10.1101/2021.07.27.21261237

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Entecavir (ETV) is a widely used anti-hepatitis B virus (HBV) drug. However, the emergence of resistant mutations in HBV reverse transcriptase (RT) results in treatment failure. To understand the mechanism underlying the development of ETV-resistance by HBV RT, we analyzed the L180M, M204V, and L180M/M204V mutants using a combination of biochemical and structural techniques. ETV-triphosphate (ETV-TP) exhibited competitive inhibition with dGTP both in wild type (wt) and M204V RT, as observed using Lineweaver-Burk Plot. By contrast, RT L180M or L180M/M204V did not fit either competitive, uncompetitive, non-competitive, or typical mixed inhibition, although ETV-TP was a competitive inhibitor of dGTP. Crystallography of HIV RTY115F/F116Y/Q151M/F160M/M184V mimicking HBV RT L180M/M204V showed that the F115 bulge (F88 in HBV RT) caused by F160M mutation induces the deviated binding of dCTP from its normal tight binding position. Modeling of ETV-TP on the deviated dCTP indicates that a steric clash could occur between ETV-TP methylene and the 3'-end nucleoside ribose. ETV-TP is likely to primarily interact with HBV RT M171 prior to final accommodation at the dNTP-binding site (Yasutake et al. Scientific Rep. (2018)8:1624/DOI:10.1038/s41598-018-19602-9). Therefore, in HBV RT L180M/M204V, ETV-TP may be stuck at M171, a residue which is conserved in almost all HBV isolates, thereby leading to the strange inhibition pattern observed in the kinetic analysis. Collectively, our results provide novel insights into the mechanism of ETV resistance of HBV RT caused by L180M/M204V mutations. IMPORTANCE HBV infects 257 million people in the world, who suffer from elevated risk of liver cirrhosis and cancer. ETV is one of the most potent anti-HBV drugs and its resistant mutations in HBV RT have been extensively studied. Nevertheless, the mechanisms underlying ETV-resistance have remained elusive. We propose an attractive hypothesis to explain ETV resistance and its effectiveness using a combination of kinetic and structural analysis. ETV is likely to have an additional interaction site, M171, besides the dNTP pocket of HBV RT; this finding indicates that nucleos(t)ide analogues (NAs) recognizing multiple interaction sites within RT may effectively inhibit the enzyme. Modification of ETV may render it more effective and enable the rational design of efficient NA inhibitors.

DOI： 10.1128/JVI.02401-20

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Proceedings of the National Academy of Sciences  

The spike (S) protein of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) plays a key role in viral infectivity. It is also the major antigen stimulating the host's protective immune response, specifically, the production of neutralizing antibodies. Recently, a new variant of SARS-CoV-2 possessing multiple mutations in the S protein, designated P.1, emerged in Brazil. Here, we characterized a P.1 variant isolated in Japan by using Syrian hamsters, a well-established small animal model for the study of SARS-CoV-2 disease (COVID-19). In hamsters, the variant showed replicative abilities and pathogenicity similar to those of early and contemporary strains (i.e., SARS-CoV-2 bearing aspartic acid [D] or glycine [G] at position 614 of the S protein). Sera and/or plasma from convalescent patients and BNT162b2 messenger RNA vaccinees showed comparable neutralization titers across the P.1 variant, S-614D, and S-614G strains. In contrast, the S-614D and S-614G strains were less well recognized than the P.1 variant by serum from a P.1-infected patient. Prior infection with S-614D or S-614G strains efficiently prevented the replication of the P.1 variant in the lower respiratory tract of hamsters upon reinfection. In addition, passive transfer of neutralizing antibodies to hamsters infected with the P.1 variant or the S-614G strain led to reduced virus replication in the lower respiratory tract. However, the effect was less pronounced against the P.1 variant than the S-614G strain. These findings suggest that the P.1 variant may be somewhat antigenically different from the early and contemporary strains of SARS-CoV-2.

DOI： 10.1073/pnas.2106535118

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Language：English   Publisher：エルゼビア・ジャパン(株)  

SARS-CoV-19の初回感染から105日後に無症候性再感染となった症例からの疫学的、臨床的、血清学的データを評価した。SARS-CoV-19のスパイクタンパク質をエンコードするDNAを保有するプラスミドをトランスフェクトされた293細胞から組換えスパイクタンパク質を調整し、IgG抗体検出ELISA用抗原とした。回復期の症例の血漿/血清からIgG分画を分離し、SARS-CoV-2と混合後、VeroE6/TMPRSS2細胞に接種培養して細胞変性効果の有無を認めた。症例は58歳男性で初感染時には胸部CT検査で両肺に多発するすりガラス陰影が認められた。酸素療法を要する中等症のCOVID-19肺炎を発症した。ファビピラビル治療を受けて症状が改善し、qRT-PCRが2回連続で陰性となり30日目に退院した。約2ヵ月半後、症例の家族3名が発症し本人もPCR陽性となったが無症候であった。初回感染から94、126、152日後の症例の抗SARS-CoV-2スパイクタンパク質IgG抗体のOD値は15.6、13.6、11.8と依然高い水準にあった。初回感染から94日後の中和抗体のIC50は50μg/mLを示した。初回感染から126日後(再感染から21日後)には14.8μg/mLと強い反応性を示し、初回発症から152日後(再感染から47日後)も20.1μg/mLと高い中和活性を示した。

Language：English   Publishing type：Research paper (scientific journal)  

BACKGROUND: In order to tackle the COVID-19 pandemic, a COVID-19 convalescent plasma (CCP) procurement program was initiated in Japan in April 2020. The program was a collaboration between a government-managed national hospital, an infectious disease research institute, and a blood banking organization. Each party assumed different responsibilities: recruitment, SARS-CoV-2 antibody profiling, and plasmapheresis; conduction of screening tests; and SARS-CoV-2 blood testing, respectively. METHODS: We adopted a two-point screening approach before the collected CCP was labeled as a CCP product for investigational use, for which we mainly tested anti-SARS-CoV-2 antibody eligibility and blood product eligibility. Anti-SARS-CoV-2 spike protein titer was measured using enzyme-linked immunosorbent assay, and the IC50 value was denoted as the neutralizing activity. Blood donor eligibility was extended beyond the normal blood donation guidelines to include a broader range of participants. After both eligibility criteria were confirmed, participants were asked to revisit the hospital for blood donation, which is a unique aspect of the Japanese CCP program, as most donations are taking place in normal blood donation venues in other countries. Some donors were re-scheduled for repeat plasma donations. As public interest in anti-SARS-CoV-2 antibodies increased, test results were given to the participants. RESULTS: As of September 17, 2020, our collection of CCP products was sufficient to treat more than 100 patients. As a result, projects for administration and distribution are also being conducted. CONCLUSIONS: We successfully implemented a CCP procurement scheme with the goal to expand to other parts of the country to improve treatment options for COVID-19.

DOI： 10.1111/trf.16541

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Language：English   Publishing type：Research paper (scientific journal)  

INTRODUCTION: "Re-infection" with COVID-19 is a growing concern; re-infection cases have reported worldwide. However, the clinical characteristics of SARS-CoV-2 re-infection, including the levels and role of anti-SARS-CoV-2 Spike protein IgG antibodies and the half-maximal concentration (IC50) of neutralizing antibodies remain unknown. METHODS: Both the epidemiological and clinical information has been collected during two episodes of COVID-19 in a patient. Laboratory results, including RT-PCR, Ct values, anti-SARS-CoV-2 Spike protein IgG antibodies, and the IC50 of neutralizing antibodies levels were analyzed on the patient. RESULTS: The patient was a 58-year-old man who developed moderate COVID-19 pneumonia with oxygen demand (cannula 2 L/min) in the first episode. By day 30, he recuperated and was discharged after testing negative for SARS-CoV-2. After two and a half months, his three family members showed COVID-19 symptoms and tested positive for SARS-CoV-2. He tested positive for SARS-CoV-2 once again and was asymptomatic (the second episode). The IC50 of neutralizing antibodies against SARS-CoV-2 greatly increased from 50.0 μg/mL (after the first episode) to 14.8 μg/mL (after the second episode), and remained strongly reactive (20.1 μl/mL) after 47 days of the second episode. CONCLUSIONS: Epidemiological, clinical, and serological analyses confirmed that the patient had re-infection instead of persistent viral shedding from first infection. Our results suggest that SARS-CoV-2 re-infection may manifest as asymptomatic with increased neutralizing antibody levels. Further studies such as the virus characteristics, immunology, and epidemiology on SARS-CoV-2 re-infection are needed.

DOI： 10.1016/j.jiac.2021.04.017

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Language：English   Publisher：エルゼビア・ジャパン(株)  

COVID-19の回復期にある患者における十分な抗SARS-CoV-2抗体産生に影響を及ぼす可能性のある因子を調べた。2020年1〜6月にCOVID-19と診断された患者84例(男性59例、年齢中央値50歳)を登録した。発症日と血液採取日を記録し、抗体価を測定した各検体について発症からの日数を算出した。SARS-CoV-2スパイクタンパク質全長をエンコードするプラスミドDNAをExpi293細胞にトランスフェクトし、発現した組換えタンパク質を精製してELISA用の抗原とした。96ウェルに抗原をコーティングし患者血清と反応後HRP標識抗ヒトIgGを添加し発色基質TMB溶液を加えて発色させ吸光度を測定した。84例中19例は回復期のみに抗体が検出された。65例は急性期と回復期の両方で抗体が検出された。多変量対数正規分析により、男性、糖尿病、急性期の最大CRP値がIgG抗体上昇と有意に関連していた。グルココルチコイドの使用は抗体価とは関連していなかった。抗体価は発症から5〜6週間でピークに達した。本調査では重症COVID-19の危険因子と特定されている糖尿病が高い抗体価をもたらした。疾患重症度よりCRP高値の方が高い抗体価に関連していた。

Language：English   Publishing type：Research paper (scientific journal)  

We assessed the consistency of seropositive results of three rapid immunoassays (Kits A, B, and C) for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) compared to highly accurate serological tests (Abbott and Roche) among healthcare workers in a hospital in Tokyo. The seroprevalence of SARS-CoV-2 immunoglobulin G was 0.41%, 2.36%, and 0.08% using Kits A, B, and C, respectively. Of the 51 samples that were seropositive on any rapid test, all were seronegative on both the Abbott and the Roche assays. Given that the seroprevalence of SARS-CoV-2 immunoglobulin G varied widely according to the choice of rapid test and the rapid test results were inconsistent with the results of highly accurate tests, the diagnostic accuracy of rapid serological tests for SARS-CoV-2 should be assessed before introducing these tests for point-of-care testing or surveillance.

DOI： 10.35772/ghm.2021.01022

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Language：English   Publisher：(国研)国立国際医療研究センター  

大規模病院の医療従事者におけるSARS-CoV-2感染の血清有病率評価において、3種類の迅速ラテラルフロー・イムノアッセイ(LFIA)が2種類の高精度実験室ベース検査の結果と一致するかを調査する横断研究を実施した。迅速LFIAはキットA、キットB、キットC、高精度血清検査はAbbottおよびRocheを用いた。SARS-CoV-2免疫グロブリンGの血清有病率はキットAで0.41%、キットBで2.36%、キットCで0.08%であった。迅速検査で血清陽性であった標本51体のうち、全標本がAbbottおよびRocheアッセイの両方で血清陰性であった。SARS-CoV-2免疫グロブリンGの血清有病率は迅速検査の選択により大きく異なり、迅速検査の結果と高精度検査の結果が一致しないことから、診療現場での検査または調査に導入する前にSARS-CoV-2に対する迅速血清検査の診断精度を評価すべきであることが示された。

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

DOI： 10.1016/j.jinf.2021.01.010

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

<title>Abstract</title>While there are various attempts to administer COVID-19-convalescent plasmas to SARS-CoV-2-infected patients, neither appropriate approach nor clinical utility has been established. We examined the presence and temporal changes of the neutralizing activity of IgG fractions from 43 COVID-19-convalescent plasmas using cell-based assays with multiple endpoints. IgG fractions from 27 cases (62.8%) had significant neutralizing activity and moderately to potently inhibited SARS-CoV-2 infection in cell-based assays; however, no detectable neutralizing activity was found in 16 cases (37.2%). Approximately half of the patients (~ 41%), who had significant neutralizing activity, lost the neutralization activity within ~ 1 month. Despite the rapid decline of neutralizing activity in plasmas, good amounts of SARS-CoV-2-S1-binding antibodies were persistently seen. The longer exposure of COVID-19 patients to greater amounts of SARS-CoV-2 elicits potent immune response to SARS-CoV-2, producing greater neutralization activity and SARS-CoV-2-S1-binding antibody amounts. The dilution of highly-neutralizing plasmas with poorly-neutralizing plasmas relatively readily reduced neutralizing activity. The presence of good amounts of SARS-CoV-2-S1-binding antibodies does not serve as a surrogate ensuring the presence of good neutralizing activity. In selecting good COVID-19-convalescent plasmas, quantification of neutralizing activity in each plasma sample before collection and use is required.

DOI： 10.1038/s41598-021-84733-5

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Other Link： http://www.nature.com/articles/s41598-021-84733-5

Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

<title>Abstract</title>The quantitative range and reproducibility of current serological tests for severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) are not optimized. Herein, we developed a diagnostic test that detects SARS-CoV-2 IgG and IgM with high quantitativeness and reproducibility and low interference. The system was based on the high-sensitivity chemiluminescence enzyme immunoassay (HISCL) platform and detects IgG and IgM specific to SARS-CoV-2 spike and nucleocapsid proteins. Quantification accuracy and reproducibility were evaluated using serially diluted samples from 60 SARS-CoV-2-infected patients. Assay performance was evaluated using serum samples from the SARS-CoV-2-infected patients and 500 SARS-CoV-2-negative serum samples collected before the emergence of SARS-CoV-2. The system showed high quantification accuracy (range, 10²), high reproducibility (within 5%), and no cross-reaction between SARS1- and MERS-S proteins. Detection accuracy was 98.3% and 93.3% for IgG and IgM against spike proteins and 100% and 71.7% for IgG and IgM against nucleocapsid proteins, respectively. Mean antibody levels were &gt; 10 times that in negative samples upon admission and &gt; 100 times that at convalescent periods. Clinical severity upon admission was not correlated with IgG or IgM levels. This highly quantitative, reproducible assay system with high clinical performance may help analyze temporal serological/immunological profiles of SARS-CoV-2 infection and SARS-CoV-2 vaccine effectiveness.

DOI： 10.1038/s41598-021-84387-3

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Other Link： http://www.nature.com/articles/s41598-021-84387-3

Language：English   Publishing type：Research paper (scientific journal)  

OBJECTIVES: Rapid antigen testing (RAT) for coronavirus disease 2019 (COVID-19) has lower sensitivity but high accuracy during the early stage when compared to reverse transcription quantitative polymerase chain reaction (RT-qPCR). The aim of this study was to investigate the concordance between RAT and RT-qPCR results, and their prediction of disease transmission. METHODS: This single-center retrospective observational study of inpatients with COVID-19 was conducted from March 6 to June 14, 2020. Nasopharyngeal swabs were used to perform RAT and RT-qPCR. The primary endpoint was concordance between RAT and RT-qPCR results. The secondary endpoints were the factors causing disagreement in the results and the estimated transmissibility in RT-qPCR-positive patients with mild symptoms. RESULTS: Overall, 229 samples in viral transport medium (VTM) were obtained from 105 patients. The positive and negative concordance rates for VTM were 41% vs 99% (κ = 0.37) and 72% vs 100% (κ = 0.50) for samples collected on disease days 2-9. An increased body temperature (odds ratio 0.54) and absence of drugs with potential antiviral effect (odds ratio 0.48) yielded conflicting results. RAT was associated with the ability to end isolation (OR 0.11, 95% confidence interval 0.20-0.61). CONCLUSIONS: RAT and RT-qPCR results were highly consistent for samples collected at the appropriate time and could be useful for inferring the possibility of transmissibility.

DOI： 10.1016/j.ijid.2020.12.079

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Language：English   Publishing type：Research paper (scientific journal)  

INTRODUCTION: Among patients with coronavirus disease 2019 (COVID-19), the factors that affect anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibody production remain unclear. This study aimed to identify such factors among patients convalescing from COVID-19. METHODS: This study comprised patients who had been diagnosed with COVID-19 between January 1 and June 30, 2020 and gave consent for anti-SARS-CoV-2 spike protein antibody measurement using enzyme-linked immunosorbent assay during their acute and/or convalescent phases. Factors related to elevated antibody titers and the relationship between the days from disease onset and the development of antibody titers were assessed. RESULTS: A total of 84 participants enrolled in the study. Nineteen participants had antibody titers measured during the convalescent phase only, and 65 participants had antibody titers measured during the acute and convalescent phases. The antibody titers peaked in weeks 5 and 6. The stepwise multivariate log-normal analysis revealed that male sex (P = 0.04), diabetes mellitus (P = 0.03), and high C-reactive protein levels during the disease course (P < 0.001) were associated with elevated IgG antibodies. Glucocorticoid use was not associated with antibody titers. CONCLUSION: The study found that high values of maximum CRP levels during the acute phase, male sex, and diabetes mellitus were associated with elevated antibody titers. Antibody titers tended to be highest in the first 5 or 6 weeks after the onset of symptoms.

DOI： 10.1016/j.jiac.2021.01.006

PubMed

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Background: To develop an effective vaccine against a novel viral pathogen, it is important to understand the longitudinal antibody responses against its first infection. Here we performed a longitudinal study of antibody responses against SARS-CoV-2 in symptomatic patients. Methods: Sequential blood samples were collected from 39 individuals at various timepoints between 0 and 154 days after onset. IgG or IgM titers to the receptor binding domain (RBD) of the S protein, the ectodomain of the S protein, and the N protein were determined by using an ELISA. Neutralizing antibody titers were measured by using a plaque reduction assay. Findings: The IgG titers to the RBD of the S protein, the ectodomain of the S protein, and the N protein peaked at about 20 days after onset, gradually decreased thereafter, and were maintained for several months after onset. Extrapolation modeling analysis suggested that the IgG antibodies were maintained for this amount of time because the rate of reduction slowed after 30 days post-onset. IgM titers to the RBD decreased rapidly and disappeared in some individuals after 90 days post-onset. All patients, except one, possessed neutralizing antibodies against authentic SARS-CoV-2, which they retained at 90 days after onset. The highest antibody titers in patients with severe infections were higher than those in patients with mild or moderate infections, but the decrease in antibody titer in the severe infection cohort was more remarkable than that in the mild or moderate infection cohort. Interpretation: Although the number of patients is limited, our results show that the antibody response against the first SARS-CoV-2 infection in symptomatic patients is typical of that observed in an acute viral infection. Funding: The Japan Agency for Medical Research and Development and the National Institutes of Allergy and Infectious Diseases.

DOI： 10.1016/j.eclinm.2021.100734

PubMed

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

Advances in antiviral therapy have dramatically improved the therapeutic effects on HIV type 1 (HIV-1) infection. However, even with potent combined antiretroviral therapy, HIV-1 latently infected cells cannot be fully eradicated. Latency-reversing agents (LRAs) are considered a potential tool for eliminating such cells; however, recent in vitro and in vivo studies have raised serious concerns regarding the efficacy and safety of the "shock and kill" strategy using LRAs. In the present study, we examined the activity and safety of a panel of protein kinase C (PKC) activators with a diacylglycerol (DAG)-lactone structure that mimics DAG, an endogenous ligand for PKC isozymes. YSE028, a DAG-lactone derivative, reversed HIV-1 latency in vitro when tested using HIV-1 latently infected cells (e.g., ACH2 and J-Lat cells) and primary cells from HIV-1-infected individuals. The activity of YSE028 in reversing HIV-1 latency was synergistically enhanced when combined with JQ1, a bromodomain and extra-terminal inhibitor LRA. DAG-lactone PKC activators also induced caspase-mediated apoptosis, specifically in HIV-1 latently infected cells. In addition, these DAG-lactone PKC activators showed minimal toxicity in vitro and in vivo. These data suggest that DAG-lactone PKC activators may serve as potential candidates for combination therapy against HIV-1 latently infected cells, especially when combined with other LRAs with a different mechanism, to minimize side effects and achieve maximum efficacy in various reservoir cells of the whole body.

DOI： 10.3389/fmicb.2021.636276

PubMed

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