Efficacy of convalescent plasma therapy for COVID-19 in Japan: An open-label, randomized, controlled trial.

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.

Multisystem Inflammatory Syndrome in Adult after First Dose of mRNA Vaccine.

A 32-year-old man in Japan experienced respiratory failure after receiving the first dose of coronavirus disease (COVID-19) vaccine. He was treated with noninvasive ventilation and corticosteroids. Serologic test results suggested previous COVID-19; therefore, he received a diagnosis of multisystem inflammatory syndrome. COVID-19 vaccination could be a trigger for this condition.

A case report of breakthrough infection with the SARS-CoV-2 delta variant and household transmission: Role of vaccination, anti-spike IgG and neutralizing activity.

There have been several reports of breakthrough infections, which are defined as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections among individuals who had received at least two doses of vaccine at least 14 days before the onset of infection, but data on the antibody titers, including SARS-CoV-2 neutralizing antibody activity, and the clinical course of individuals with breakthrough infections are limited. We encountered a case of breakthrough infection with the SARS-CoV-2 delta variant in a 31-year-old female healthcare worker (the index case, Case 1) and a secondary case (Case 2) in her unvaccinated 33-year-old husband. We studied the role of the anti-spike immunoglobulin G (IgG) and neutralizing antibody activity in the two case patients. Case 1 had high anti-spike IgG detected on day 3 of the illness, with low neutralizing antibody activity. The neutralizing antibody activity started to increase on day 5 of the illness. In Case 2 both the anti-spike IgG and the neutralizing antibody activity remained low from days 4-11 of illness, and the anti-spike IgG gradually increased from day 9. In Case 1, the fever broke within 4 days of onset, coinciding with the rise in neutralizing antibodies, whereas the fever took 7 days to resolve in Case 2. SARS-CoV-2 infection can occur even in vaccinated individuals, but vaccination may contribute to milder clinical symptoms because neutralizing antibodies are induced earlier in vaccinated individuals than in unvaccinated individuals.

Prolonged SARS-CoV-2 infection associated with long-term corticosteroid use in a patient with impaired B-cell immunity.

Corticosteroids are widely used to treat severe COVID-19, but in immunocompromised individuals, who are susceptible to persistent infection, long term corticosteroid use may delay viral clearance. We present a case of prolonged SARS-CoV-2 infection in a man with significantly impaired B-cell immunity due to non-Hodgkin lymphoma which had been treated with rituximab. SARS-CoV-2 shedding persisted, despite treatment with remdesivir. Viral sequencing confirmed the persistence of the same viral strain, ruling out the possibility of reinfection. Although SARS-CoV-2 IgG, IgA and IgM remained negative throughout the treatment period, after reduction of the corticosteroid dose, PCR became negative. Long-term corticosteroid treatment, especially in immunocompromised individuals, may result in suppression of cell-mediated immunity and prolonged SARS-CoV-2 infection.

Formation Mechanism and Toxicological Significance of Biogenic Mercury Selenide Nanoparticles in Human Hepatoma HepG2 Cells.

It is widely recognized that the toxicity of mercury (Hg) is attenuated by the simultaneous administration of selenium (Se) compounds in various organisms. In this study, we revealed the mechanisms underlying the antagonistic effect of sodium selenite (Na2SeO3) on inorganic Hg (Hg2+) toxicity in human hepatoma HepG2 cells. Observations by transmission electron microscopy indicated that HgSe (tiemannite) granules of up to 100 nm in diameter were accumulated in lysosomal-like structures in the cells. The HgSe granules were composed of a number of HgSe nanoparticles, each measuring less than 10 nm in diameter. No accumulation of HgSe nanoparticles in lysosomes was observed in the cells exposed to chemically synthesized HgSe nanoparticles. This suggests that intracellular HgSe nanoparticles were biologically generated from Na2SeO3 and Hg2+ ions transported into the cells and were not derived from HgSe nanoparticles formed in the extracellular fluid. Approximately 85% of biogenic HgSe remained in the cells at 72 h post culturing, indicating that biogenic HgSe was hardly excreted from the cells. Moreover, the cytotoxicity of Hg2+ was ameliorated by the simultaneous exposure to Na2SeO3 even before the formation of insoluble HgSe nanoparticles. Our data confirmed for the first time that HepG2 cells can circumvent the toxicity of Hg2+ through the direct interaction of Hg2+ with a reduced form of Se (selenide) to form HgSe nanoparticles via a Hg-Se soluble complex in the cells. Biogenic HgSe nanoparticles are considered the ultimate metabolite in the Hg detoxification process.

How we secured a COVID-19 convalescent plasma procurement scheme in Japan.

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.

Asymptomatic COVID-19 re-infection in a Japanese male by elevated half-maximal inhibitory concentration (IC50) of neutralizing antibodies.

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.

Factors associated with anti-SARS-CoV-2 IgG antibody production in patients convalescing from COVID-19.

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.

Retrotransposition and senescence in mouse heart tissue by viral protein R of human immunodeficiency virus-1.

Combination antiretroviral therapy (cART) has greatly improved the prognosis of patients with human immunodeficiency virus type-1 (HIV-1) infection. However, cardiovascular disease (CVD) remains a serious issue even in the post-cART era. Viral protein R (Vpr), an accessory gene product of HIV-1, exerts pleiotropic activities such as the induction of DNA damage signals, apoptosis by mitochondrial membrane depolarization, G2/M-phase cell cycle abnormalities, and retrotransposition. Importantly, some of these cellular responses are induced by the trans-acting activity of Vpr. Recently, we established an enzyme-linked immunosorbent assay to detect Vpr and reported that about 22% of blood samples from 100 HIV-1-positive patients were positive for Vpr. Here, we investigated the biological effects of recombinant Vpr (rVpr) in vivo. We observed that repeated injections of rVpr increased the copy number of long interspersed element-1 (L1) in the heart genome in mice. rVpr also increased the number of cells positive for senescence-associated ß-galactosidase (SA-ß-gal) and fibrosis in the heart. Notably, co-administration of a reverse transcriptase inhibitor reduced the number of rVpr-induced SA-ß-gal-positive cells and fibrosis concomitantly with the attenuation of L1 retrotransposition. Interestingly, a Vpr mutant defective for mitochondrial dysfunction also induced heart senescence and increased L1 copy number. Together with a recent report that L1 retrotransposition functions as a molecular basis of senescence, our current data suggest that rVpr-induced L1 retrotransposition is linked with senescence in heart tissue. We would propose that Vpr in the bloodstream may be one of risk factors for CVD, and that its monitoring will lead to well understanding of the heterogeneity and multifactorial mechanisms of CVD in HIV-1 patients.

Imaging of intracellular fatty acids by scanning X-ray fluorescence microscopy.

Fatty acids are taken up by cells and incorporated into complex lipids such as neutral lipids and glycerophospholipids. Glycerophospholipids are major constituents of cellular membranes. More than 1000 molecular species of glycerophospholipids differ in their polar head groups and fatty acid compositions. They are related to cellular functions and diseases and have been well analyzed by mass spectrometry. However, intracellular imaging of fatty acids and glycerophospholipids has not been successful due to insufficient resolution using conventional methods. Here, we developed a method for labeling fatty acids with bromine (Br) and applied scanning X-ray fluorescence microscopy (SXFM) to obtain intracellular Br mapping data with submicrometer resolution. Mass spectrometry showed that cells took up Br-labeled fatty acids and metabolized them mainly into glycerophospholipids in CHO cells. Most Br signals observed by SXFM were in the perinuclear region. Higher resolution revealed a spot-like distribution of Br in the cytoplasm. The current method enabled successful visualization of intracellular Br-labeled fatty acids. Single-element labeling combined with SXFM technology facilitates the intracellular imaging of fatty acids, which provides a new tool to determine dynamic changes in fatty acids and their derivatives at the single-cell level.-Shimura, M., Shindou, H., Szyrwiel, L., Tokuoka, S. M., Hamano, F., Matsuyama, S., Okamoto, M., Matsunaga, A., Kita, Y., Ishizaka, Y., Yamauchi, K., Kohmura, Y., Lobinski, R., Shimizu, I., Shimizu, T. Imaging of intracellular fatty acids by scanning X-ray fluorescence microscopy.

SMAD4-deficient intestinal tumors recruit CCR1+ myeloid cells that promote invasion.

Inactivation of TGF-beta family signaling is implicated in colorectal tumor progression. Using cis-Apc(+/Delta716) Smad4(+/-) mutant mice (referred to as cis-Apc/Smad4), a model of invasive colorectal cancer in which TGF-beta family signaling is blocked, we show here that a new type of immature myeloid cell (iMC) is recruited from the bone marrow to the tumor invasion front. These CD34(+) iMCs express the matrix metalloproteinases MMP9 and MMP2 and the CC-chemokine receptor 1 (CCR1) and migrate toward the CCR1 ligand CCL9. In adenocarcinomas, expression of CCL9 is increased in the tumor epithelium. By deleting Ccr1 in the background of the cis-Apc/Smad4 mutant, we further show that lack of CCR1 prevents accumulation of CD34(+) iMCs at the invasion front and suppresses tumor invasion. These results indicate that loss of transforming growth factor-beta family signaling in tumor epithelium causes accumulation of iMCs that promote tumor invasion.

Effects of antibody to receptor activator of nuclear factor κ-B ligand on inflammation and cartilage degradation in collagen antibody-induced arthritis in mice.

BACKGROUND: Rheumatoid arthritis (RA) is an inflammatory disease that leads to destruction of both articular cartilage and bone tissues. In rheumatic joints, synoviocytes and T-lymphocytes as well as bone cells produce the receptor activator of nuclear factor κ-B (RANK) ligand (RANKL), which binds to RANK on the surface of osteoclasts and their precursor cells to induce differentiation and activation of osteoclasts. Hence, inhibition of RANKL may be a promising approach to suppress osteolysis in RA. On the other hand, RANKL production by lymphocytes indicates the possibility that its inhibition would be effective to suppress inflammation in RA. In addition, it has been reported that cathepsin K, a predominant cysteine protease in osteoclasts, is involved in cartilage destruction in RA model mice. Here, we evaluated the effects of an anti-RANKL antibody on inflammation in footpads and degradation of articular cartilage in RA model mice. RESULTS: We induced arthritis in mice by injection of anti-type II collagen antibodies and lipopolysaccharide (LPS). Inhibition of RANKL by an anti-RANKL antibody (OYC1, Oriental Yeast, Tokyo, Japan) was confirmed by increased bone volume in the metaphysis of tibias. Swelling in either limb until day 14 was seen in 5 of 6 mice injected with anti-collagen antibodies and LPS without treatment with OYC1, while that was seen in 4 of 5 mice treated with OYC1. The average arthritis scores on day 14 in those groups were 2.17 and 3.00, respectively, indicating that OYC1 did not ameliorate inflammation in the limbs. Histological analyses indicated that OYC1 does not protect articular cartilage from destruction in mice with arthritis. CONCLUSIONS: Our present study failed to show the effectiveness of an anti-RANKL antibody to ameliorate inflammation in the limbs or protect articular cartilage from degradation in a collagen antibody-induced arthritis mouse model.

Identification of viral protein R of human immunodeficiency virus-1 (HIV) and interleukin-6 as risk factors for malignancies in HIV-infected individuals: A cohort study.

BACKGROUND: Despite effective antiretroviral therapy, patients with human immunodeficiency virus type-1 (HIV) suffer from a high frequency of malignancies, but related risk factors remain elusive. Here, we focused on blood-circulating viral protein R (Vpr) of HIV, which induces proinflammatory cytokine production and genotoxicity by exogenous functions. METHODS AND FINDINGS: A total 404 blood samples of HIV patients comprising of 126 patients with malignancies (tumor group) and 278 patients without malignancies (non-tumor group), each of 96 samples was first selected by one-to-one propensity score matching. By a detergent-free enzyme-linked immunosorbent assays (detection limit, 3.9 ng/mL), we detected Vpr at a higher frequency in the matched tumor group (56.3%) than in the matched non-tumor group (39.6%) (P = 0.030), although there was no different distribution of Vpr levels (P = 0.372). We also detected anti-Vpr immunoglobulin (IgG), less frequently in the tumor group compared with the tumor group (22.9% for tumor group vs. 44.8% for non-tumor group, P = 0.002), and the proportion of patients positive for Vpr but negative of anti-Vpr IgG was significantly higher in the tumor group than in the non-tumor group (38.6% vs. 15.6%, respectively, P < 0.001). Additionally, Interleukin-6 (IL-6), the levels of which were high in HIV-1 infected patients (P < 0.001) compared to non-HIV-infected individuals, was significantly higher in advanced cases of tumors (P < 0.001), and IL-6 level was correlated with Vpr in the non-tumor group (P = 0.010). Finally, multivariate logistic regression analysis suggested a positive link of Vpr with tumor occurrence in HIV patients (P = 0.002). CONCLUSION: Vpr and IL-6 could be risk factors of HIV-1 associated malignancies, and it would be importance to monitor these molecules for well managing people living with HIV-1.

Viral protein R of human immunodeficiency virus type-1 induces retrotransposition of long interspersed element-1.

BACKGROUND: Viral protein R (Vpr), a protein of human immunodeficiency virus type-1 (HIV-1) with various biological functions, was shown to be present in the blood of HIV-1-positive patients. However, it remained unclear whether circulating Vpr in patients' blood is biologically active. Here, we examined the activity of blood Vpr using an assay system by which retrotransposition of long interspersed element-1 (L1-RTP) was detected. We also investigated the in vivo effects of recombinant Vpr (rVpr) by administrating it to transgenic mice harboring human L1 as a transgene (hL1-Tg mice). Based on our data, we discuss the involvement of blood Vpr in the clinical symptoms of acquired immunodeficiency syndrome (AIDS). RESULTS: We first discovered that rVpr was active in induction of L1-RTP. Biochemical analyses revealed that rVpr-induced L1-RTP depended on the aryl hydrocarbon receptor, mitogen-activated protein kinases, and CCAAT/enhancer-binding protein ß. By using a sensitive L1-RTP assay system, we showed that 6 of the 15 blood samples from HIV-1 patients examined were positive for induction of L1-RTP. Of note, the L1-RTP-inducing activity was blocked by a monoclonal antibody specific for Vpr. Moreover, L1-RTP was reproducibly induced in various organs, including the kidney, when rVpr was administered to hL1-Tg mice. CONCLUSIONS: Blood Vpr is biologically active, suggesting that its monitoring is worthwhile for clarification of the roles of Vpr in the pathogenesis of AIDS. This is the first report to demonstrate a soluble factor in patients' blood active for L1-RTP activity, and implies the involvement of L1-RTP in the development of human diseases.

Robust protein-based engineering of hepatocyte-like cells from human mesenchymal stem cells.

BACKGROUND: Cells of interest can be prepared from somatic cells by forced expression of lineage-specific transcription factors, but it is required to establish a vector-free system for their clinical use. Here, we report a protein-based artificial transcription system for engineering hepatocyte-like cells from human umbilical cord-derived mesenchymal stem cells (MSCs). METHODS: MSCs were treated for 5 days with 4 artificial transcription factors (4F), which targeted hepatocyte nuclear factor (HNF)1α, HNF3γ, HNF4α, and GATA-binding protein 4 (GATA4). Then, engineered MSCs (4F-Heps) were subjected to epigenetic analysis, biochemical analysis and flow cytometry analysis with antibodies to marker proteins of mature hepatocytes and hepatic progenitors such as delta-like homolog 1 (DLK1) and trophoblast cell surface antigen 2 (TROP2). Functional properties of the cells were also examined by injecting them to mice with lethal hepatic failure. RESULTS: Epigenetic analysis revealed that a 5-day treatment of 4F upregulated the expression of genes involved in hepatic differentiation, and repressed genes related to pluripotency of MSCs. Flow cytometry analysis detected that 4F-Heps were composed of small numbers of mature hepatocytes (at most 1%), bile duct cells (~19%) and hepatic progenitors (~50%). Interestingly, ~20% of 4F-Heps were positive for cytochrome P450 3A4, 80% of which were DLK1-positive. Injection of 4F-Heps significantly increased survival of mice with lethal hepatic failure, and transplanted 4F-Heps expanded to more than 50-fold of human albumin-positive cells in the mouse livers, well consistent with the observation that 4F-Heps contained DLK1-positive and/or TROP2-positive cells. CONCLUSION: Taken together with observations that 4F-Heps were not tumorigenic in immunocompromised mice for at least 2 years, we propose that this artificial transcription system is a versatile tool for cell therapy for hepatic failures.

Inhaled ciclesonide does not affect production of antibodies or elimination of virus in patients with COVID-19: Subanalysis of a multicenter, open-label randomized trial.

During an earlier multicenter, open-label, randomized controlled trial designed to evaluate the effectiveness of high-dose inhaled ciclesonide in patients with asymptomatic or mild coronavirus disease 2019 (COVID-19), we observed that worsening of shadows on CT without worsening of clinical symptoms was more common with ciclesonide. The present study sought to determine if an association exists between worsening CT shadows and impaired antibody production in patients treated with inhaled ciclesonide. Eighty-nine of the 90 patients in the original study were prospectively enrolled. After exclusions, there were 36 patients each in the ciclesonide and control groups. We analyzed antibody titers against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) nucleocapsid protein at various time points. Changes in viral load during treatment were compared. There was no significant difference in age, sex, body mass index, background clinical characteristics, or symptoms between the two groups. Although evaluation on day 8 suggested a greater tendency for worsening shadows on CT in the ciclesonide group (p = 0.072), there was no significant difference between them in the ability to produce antibodies (p = 0.379) or the maximum antibody titer during the clinical course. In both groups, worsening CT shadows and higher viral loads were observed on days 1-8, suggesting ciclesonide does not affect clearance of the virus (p = 0.134). High-dose inhaled ciclesonide did not impair production of antibodies against SARS-CoV-2 or affect elimination of the virus, suggesting that this treatment can be used safely in patients with COVID-19 patients who use inhaled steroids for asthma and other diseases.

Association between SARS-CoV-2 anti-spike antibody titers and the development of post-COVID conditions: A retrospective observational study.

The symptoms that persist after an acute coronavirus disease 2019 (COVID-19) are referred to as post- COVID conditions. Although the cause of post-COVID conditions remains unclear, the host immune response to SARS-CoV-2 may be involved. Hence, we aimed to investigate the effect of serum antibody titers against SARS-CoV-2 on the development of post-COVID conditions. We conducted a retrospective observational study of COVID-19-recovered individuals who attended the clinic at the National Center for Global Health and Medicine between January 2020 and April 2021. Serum SARS-CoV-2 anti-spike antibody titers were measured and a questionnaire survey was used to collect information on the presence of post-COVID conditions and demographic characteristics of the participants. Participants were then divided into two groups: high peak antibody titer group [≥ 0.759 OD450 value], and low peak antibody titer group [< 0.759 OD450 value] and compared their frequency of post-COVID conditions. Of 526 individuals attending the clinic, 457 (86.9%) responded to the questionnaire. We analyzed the data of 227 (49.7%) participants with measurements of serum antibody titers during the peak period. The incidence of depressed mood was significantly higher in the group with higher antibody titers (odds ratio: 2.34, 95% CI: 1.17-4.67, p = 0.016). There was no significant difference in the frequency of the remaining symptoms between the two groups. Among post-COVID conditions, the depressed mood was more frequent in the group with high serum antibody titers which suggests a difference in pathogenesis between depressive mood and other post-COVID conditions that requires further investigation.

Trends of participants in convalescent plasma donation for COVID-19 in Japan as the pandemic evolved.

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.

Long COVID: current status in Japan and knowledge about its molecular background.

Even after recovering from coronavirus disease 2019 (COVID-19), patients can experience prolonged complaints, referred to as "long COVID". Similar to reports in Caucasians, a follow-up study in Japan revealed that fatigue, dyspnea, cough, anosmia/dysgeusia, and dyssomnia are common symptoms. Although the precise mode of long COVID remains elusive, multiple etiologies such as direct organ damage by infection with severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), autoimmunity, prolonged inflammatory reactions, and psychiatric impairment seem to be involved. Notably, SARS-CoV-2 is neurotropic, and viral RNA and proteins are continuously detectable in multiple organs, including the brain. Viral proteins exert a number of different toxic effects on cells, suggesting that persistent infection is a key element for understanding long COVID. Here, we first reviewed the current status of long COVID in Japan, and then summarized literature that help us understand the molecular background of the symptoms. Finally, we discuss the feasibility of vaccination as a treatment for patients with long COVID.