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There have been arguments on whether angiotensin-converting enzyme inhibitor (ACEI) and angiotensin receptor blocker (ARB) treatment alters the risk of coronavirus disease 2019 (COVID-19) susceptibility and disease severity. We identified a total of 102 eligible studies for systematic review, in which 49 studies adjusting for confounders were included in the meta-analysis. We found no association between prior ACEI/ARB use and risk of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in the general population (adjusted odds ratio [aOR], 1.00; 95% confidence interval [CI],.94–1.05). The risk of mortality (aOR,.87; 95% CI,.66–1.04) and severe outcomes (aOR,.95; 95% CI,.73–1.24) were also unchanged among COVID-19 patients taking ACEIs/ARBs. These findings remained consistent in subgroup analyses stratified by populations, drug exposures, and other secondary outcomes. This systematic review provides evidence-based support to current medical guidelines and position statements that ACEIs/ARBs should not be discontinued. Additionally, there has been no evidence for initiating ACEI/ARB regimen as prevention or treatment of COVID-19. [ABSTRACT FROM AUTHOR]

Background The characteristics of neutralizing antibodies (NAbs) and antibody against major antigen proteins related to clinical outcomes in severe coronavirus disease 2019 (COVID-19) patients were still less known. Methods NAbs and antibodies targeting nucleocapsid (N), spike protein (S), and the receptor-binding domain (RBD) in longitudinal plasma samples from the LOTUS China trial were measured by microneutralization assay and enzyme-linked immunosorbent assay (ELISA). Viral load was determined by real-time reverse transcription polymerase chain reaction (RT-PCR). A total of 576 plasma and 576 throat swabs were collected from 191 COVID-19 patients. Antibody titers related to adverse outcome and clinical improvement were analyzed. Multivariable adjusted generalized linear mixed model for random effects were developed. Results After day 28 post symptoms onset, the rate of antibody positivity reached 100% for RBD-immunoglobulin M (IgM), 97.8% for S-IgM, 100% for N-immunoglobulin G (IgG), 100% for RBD-IgG, 91.1% for N-IgM, and 91.1% for NAbs. The NAbs titers increased over time in both survivors and nonsurvivors and correlated to IgG antibodies against N, S, and RBD, whereas its presence showed no statistical correlation with death. N-IgG (slope −2.11, 95% confidence interval [CI] −3.04 to −1.18, P <.0001), S-IgG (slope −2.44, 95% CI −3.35 to −1.54, P <.0001), and RBD-IgG (slope −1.43, 95% CI −1.98 to −.88, P <.0001) were negatively correlated with viral load. S-IgG titers were lower in nonsurvivors than survivors (P =.020) at week 4 after symptoms onset. Conclusions IgM and IgG against N, S, and RBD and NAbs developed in most severe COVID-19 patients and do not correlate clearly with clinical outcomes. The levels of IgG antibodies against N, S, and RBD were related to viral clearance. [ABSTRACT FROM AUTHOR]

Background Human metapneumovirus (HMPV) is a leading cause of respiratory tract infection in children and adults. However, mechanisms of pathogenesis are not fully understood. Methods We tested HMPV clinical and laboratory isolates in an established C57BL/6 mouse model and measured weight loss, airway function, and viral titers. Immune responses were determined using cytokine quantitation and flow cytometry. Results HMPV clinical isolates induced variable disease severity ranging from mild to fatal disease. Laboratory strain TN/94-49 did not cause weight loss, but mice infected with clinical isolate C2-202 showed dramatic weight loss and 40% mortality within 5 days post-infection (Figure 1). These findings were confirmed in other inbred mouse strains. C2-202-infected mice also suffered from impaired pulmonary function post-recovery. Lung viral titer did not correlate with disease severity, suggesting immune-mediated pathogenesis. C2-202-infected mice exhibited increased production of type I and III interferons (IFN) and pro-inflammatory cytokines, and lung neutrophil infiltration. However, neutrophil depletion or inflammasome inactivation did not reduce disease. Stat1/Stat2 double knockout (KO) mice lacking type I and III IFN signaling exhibited reduced weight loss but increased lung viral titer after C2-202 infection (Figure 2). Type I IFN receptor (IFNAR) KO mice infected with C2-202 had reduced weight loss but unchanged lung viral titer (Figure 3), while the addition of type III IFN blockade to C2-202-infected IFNAR mice had no effect on disease but increased lung viral titer (Figure 4). Conclusion These results suggest that severe disease caused by virulent HMPV was due to exuberant IFN response. Moreover, type I IFN was primarily associated with disease, while type III IFN was associated with viral clearance. These data suggest that IFN signaling plays an important role in HMPV pathogenesis, and thus serves as a potential therapeutic target. Disclosures All Authors: No reported Disclosures. [ABSTRACT FROM AUTHOR]