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Background The extent of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) exposure and transmission in Mali and the surrounding region is not well understood. We aimed to estimate the cumulative incidence of SARS-CoV-2 in 3 communities and understand factors associated with infection. Methods Between July 2020 and January 2021, we collected blood samples and demographic, social, medical, and self-reported symptoms information from residents aged 6 months and older over 2 study visits. SARS-CoV-2 antibodies were measured using a highly specific 2-antigen enzyme-linked immunosorbent assay optimized for use in Mali. We calculated cumulative adjusted seroprevalence for each community and evaluated factors associated with serostatus at each visit by univariate and multivariate analysis. Results Overall, 94.8% (2533/2672) of participants completed both study visits. A total of 31.3% (837/2672) were aged <10 years, 27.6% (737/2672) were aged 10–17 years, and 41.1% (1098/2572) were aged ≥18 years. The cumulative SARS-CoV-2 exposure rate was 58.5% (95% confidence interval, 47.5–69.4). This varied between sites and was 73.4% in the urban community of Sotuba, 53.2% in the rural town of Bancoumana, and 37.1% in the rural village of Donéguébougou. Study site and increased age were associated with serostatus at both study visits. There was minimal difference in reported symptoms based on serostatus. Conclusions The true extent of SARS-CoV-2 exposure in Mali is greater than previously reported and may now approach hypothetical "herd immunity" in urban areas. The epidemiology of the pandemic in the region may be primarily subclinical and within background illness rates. [ABSTRACT FROM AUTHOR]

Background: False positivity may hinder the utility of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) serological tests in sub-Saharan Africa.Methods: From 312 Malian samples collected before 2020, we measured antibodies to the commonly tested SARS-CoV-2 antigens and 4 other betacoronaviruses by enzyme-linked immunosorbent assay (ELISA). In a subset of samples, we assessed antibodies to a panel of Plasmodium falciparum antigens by suspension bead array and functional antiviral activity by SARS-CoV-2 pseudovirus neutralization assay. We then evaluated the performance of an ELISA using SARS-CoV-2 spike protein and receptor-binding domain developed in the United States using Malian positive and negative control samples. To optimize test performance, we compared single- and 2-antigen approaches using existing assay cutoffs and population-specific cutoffs.Results: Background reactivity to SARS-CoV-2 antigens was common in prepandemic Malian samples. The SARS-CoV-2 reactivity varied between communities, increased with age, and correlated negligibly/weakly with other betacoronavirus and P falciparum antibodies. No prepandemic samples demonstrated functional activity. Regardless of the cutoffs applied, test specificity improved using a 2-antigen approach. Test performance was optimal using a 2-antigen assay with population-specific cutoffs (sensitivity, 73.9% [95% confidence interval {CI}, 51.6-89.8]; specificity, 99.4% [95% CI, 97.7-99.9]).Conclusions: We have addressed the problem of SARS-CoV-2 seroassay performance in Africa by using a 2-antigen assay with cutoffs defined by performance in the target population. [ABSTRACT FROM AUTHOR]

Background: Seasonal malaria chemoprevention (SMC) is a novel strategy to reduce malaria infections in children. Infection with Plasmodium falciparum results in immune dysfunction characterized by elevated expression of markers associated with exhaustion, such as PD1 and LAG3, and regulatory CD4+FOXP3+ T cells.Methods: In the current study, the impact of seasonal malaria chemoprevention on malaria-induced immune dysfunction, as measured by markers associated with exhaustion and regulatory T cells, was explored by flow cytometry.Results: Children that received seasonal malaria chemoprevention had fewer malaria episodes and showed significantly lower fold changes in CD4+PD1+ and CD4+PD1+LAG3+ compared to those that did not receive SMC. Seasonal malaria chemoprevention had no observable effect on fold changes in CD8 T cells expressing PD1 or CD160. However, children receiving SMC showed greater increases in CD4+FOXP3+ T regulatory cells compared to children not receiving SMC.Conclusions: These results provide important insights into the dynamics of malaria-induced changes in the CD4 T-cell compartment of the immune system and suggest that the reduction of infections due to seasonal malaria chemoprevention may also prevent immune dysfunction.Clinical Trials Registration: NCT02504918. [ABSTRACT FROM AUTHOR]

Objective: Oxidants such as nitric oxide (NO) and superoxide are involved in coronary endothelial dysfunction, an early event in the process of allograft coronary atherogenesis, possibly by activation of matrix metalloproteinases (MMPs) and extracellular matrix proteins. We investigated the contribution of inducible nitric oxide synthase (iNOS) derived NO and superoxide on (MMP)-9 activity and to changes in coronary vasomotor function in rat cardiac allografts. Methods and Results: An allogenic (Brown Norway to Lewis rats) heterotopic cardiac transplantation model was used to study the effect of continuous treatment with a selective iNOS inhibitor; N-(3-(aminomethyl) benzyl) acetamidine (1400W), and polyethylene glycol conjugated superoxide dismutase (SOD) either alone or in combination on coronary vasomotor dysfunction. 1400W or SOD 24 h alone or their combination improved endothelium-dependent (bradykinin) and -independent (sodium nitroprusside) coronary flow reserve and inhibited enhanced MMP-9 protein and activity. In addition, histopathological study revealed that either 1400W or SOD or their combination reduced superoxide production and nitrotyrosine protein. Conclusion: The present study demonstrates for the first time that selective iNOS inhibition or SOD treatment reduces enhanced MMP-9 protein and activity associated with improvement of both, endothelium-dependent and -independent coronary vasomotor function in rat cardiac allografts. This is accompanied by reduction of nitrotyrosine and superoxide production. This suggests that the proteolytic enzyme MMP-9 is an effector molecule of oxidant-mediated coronary vasomotor dysfunction. [Copyright &y& Elsevier]