Two-Step In Vitro Model to Evaluate the Cellular Immune Response to SARS-CoV-2.

The cellular immune response plays an important role in COVID-19, caused by SARS-CoV-2. This feature makes use of in vitro models' useful tools to evaluate vaccines and biopharmaceutical effects. Here, we developed a two-step model to evaluate the cellular immune response after SARS-CoV-2 infection-induced or spike protein stimulation in peripheral blood mononuclear cells (PBMC) from both unexposed and COVID-19 (primo-infected) individuals (Step1). Moreover, the supernatants of these cultures were used to evaluate its effects on lung cell lines (A549) (Step2). When PBMC from the unexposed were infected by SARS-CoV-2, cytotoxic natural killer and nonclassical monocytes expressing inflammatory cytokines genes were raised. The supernatant of these cells can induce apoptosis of A549 cells (mock vs. Step2 [mean]: 6.4% × 17.7%). Meanwhile, PBMCs from primo-infected presented their memory CD4+ T cells activated with a high production of IFNG and antiviral genes. Supernatant from past COVID-19 subjects contributed to reduce apoptosis (mock vs. Step2 [ratio]: 7.2 × 1.4) and to elevate the antiviral activity (iNOS) of A549 cells (mock vs. Step2 [mean]: 31.5% × 55.7%). Our findings showed features of immune primary cells and lung cell lines response after SARS-CoV-2 or spike protein stimulation that can be used as an in vitro model to study the immunity effects after SARS-CoV-2 antigen exposure.

Investigation of Human IFITM3 Polymorphisms rs34481144A and rs12252C and Risk for Influenza A(H1N1)pdm09 Severity in a Brazilian Cohort.

Influenza is a major public health problem that causes acute respiratory infection in humans. Identification of host factors influencing in disease outcome is critical for recognition of individuals with increased risk. Investigations on the role of rs34481144A and rs12252C IFITM3 polymorphisms in influenza A(H1N1)pdm09 severity is not yet conclusively determined. This study aimed to evaluate such polymorphisms frequencies and IFITM3 levels in an infected Brazilian cohort of 314 influenza A(H1N1)pdm09 cases and its putative association with clinical, epidemiological and virological data. Individuals were clinically classified into mild, severe and fatal cases. IFITM3 polymorphisms were detected by specific Taqman probes in real time PCR reactions. IFITM3 levels were determined by quantitative real time PCR. Thus, the different clinical groups presented similar distribution of rs34481144 and rs12252 genotypes and allelic frequencies. There was no significant association between the polymorphisms with severity of disease by using distinct genetic models. Additionally, geographic distribution of mutants showed that rs34481144A allele was more predominant in Brazilian Southern region. In contrast, rs12252C allele presented similar frequencies in all regions. Individuals with the distinct rs34481144 and rs12252 genotypes showed similar levels of IFITM3 and viral load in their respiratory specimens. Furthermore, IFITM3 levels were comparable in the distinct clinical groups and were not correlated with influenza viral load in analyzed samples. Thereby, rs34481144A and rs12252C polymorphisms were not associated with severity or mortality of influenza A(H1N1)pdm09 infection nor with IFITM3 transcript levels and influenza viral load in upper respiratory tract samples in a Brazilian cohort.

Human CCR5Δ32 (rs333) polymorphism has no influence on severity and mortality of influenza A(H1N1)pdm09 infection in Brazilian patients from the post pandemic period.

BACKGROUND: Influenza is an acute and highly contagious viral respiratory infection that causes significant morbidity and mortality. The identification of host genetic factors associated with susceptibility and severity of influenza virus infection is of paramount importance. Previous studies evaluating the potential involvement of the CCR5Δ32 polymorphism (rs333), a 32 base pair deletion in CC motif chemokine receptor 5 (CCR5) gene, in severity and mortality of influenza A(H1N1)pdm09 infected individuals have been reported, but their results are quite conflicting. OBJECTIVES: The aim of this study was the evaluation of the CCR5Δ32 frequency in individuals with mild, severe and fatal influenza A(H1N1)pdm09 infection and its putative association with clinical and epidemiologic data. PATIENTS/METHODS: A total of 432 individuals were included in this study and classified according to their clinical status, into the following groups: influenza like illness (ILI) (n = 153); severe acute respiratory infection (SARI) (n = 173) and fatal (n = 106) cases. The samples were collected in the post pandemic period, from 2012 to 2018. Individuals were further stratified according to their clinical and epidemiological data. The CCR5Δ32 variant was genotyped by PCR amplification and a subset of samples was further submitted to Sanger sequencing. RESULTS: The different clinical groups (ILI, SARI and fatal) presented similar distribution of wt/wt and wt/Δ32 genotypes and CCR5Δ32 allele frequencies. Genotype Δ32/Δ32 was not detected in our study. Additionally, no association between wt/wt and wt/Δ32 genotypes and dyspnea, a clinical factor for influenza complications was found. Similarly, no significant differences in the distribution of wt/wt and wt/Δ32 genotypes and CCR5Δ32 variant allele frequencies were observed in samples from the different Brazilian geographical regions. CONCLUSIONS: The CCR5Δ32 variant does not influence the susceptibility to influenza A(H1N1)pdm09 severe disease or mortality in individuals from Brazil.