HLA Genotypes in Patients with Infection Caused by Different Strains of SARS-CoV-2.

The aggressive infectious nature of SARS-CoV-2, its rapid spread, and the emergence of mutations necessitate investigation of factors contributing to differences in SARS-CoV-2 susceptibility and severity. The role of genetic variations in the human HLA continues to be studied in various populations in terms of both its effect on morbidity and clinical manifestation of illness. The study included 484 COVID-19 convalescents (northwest Russia residents of St.

Heterogenous CD8+ T Cell Maturation and 'Polarization' in Acute and Convalescent COVID-19 Patients.

Background: The adaptive antiviral immune response requires interaction between CD8+ T cells, dendritic cells, and Th1 cells for controlling SARS-CoV-2 infection, but the data regarding the role of CD8+ T cells in the acute phase of COVID-19 and post-COVID-19 syndrome are still limited.

Methods: . Peripheral blood samples collected from patients with acute COVID-19 ( 71), convalescent subjects bearing serum SARS-CoV-2 N-protein-specific IgG antibodies ( 51), and healthy volunteers with no detectable antibodies to any SARS-CoV-2 proteins (HC, 46) were analyzed using 10-color flow cytometry.

Alterations in B Cell and Follicular T-Helper Cell Subsets in Patients with Acute COVID-19 and COVID-19 Convalescents.

Background: Humoral immunity requires interaction between B cell and T follicular helper cells (Tfh) to produce effective immune response, but the data regarding a role of B cells and Tfh in SARS-CoV-2 defense are still sparse.

Methods: Blood samples from patients with acute COVID-19 ( = 64), convalescents patients who had specific IgG to SARS-CoV-2 N-protein ( = 55), and healthy donors with no detectable antibodies to any SARS-CoV-2 proteins (HC, = 44) were analyses by multicolor flow cytometry.

Results: Patients with acute COVID-19 showed decreased levels of memory B cells subsets and increased proportion plasma cell precursors compared to HC and COVID-19 convalescent patients, whereas for the latter the elevated numbers of virgin naïve, Bm2' and "Bm3+Bm4" was found if compared with HC.

Changes in Anti-SARS-CoV-2 IgG Subclasses over Time and in Association with Disease Severity.

IgG is the most prominent marker of post-COVID-19 immunity. Not only does this subtype mark the late stages of infection, but it also stays in the body for a timespan of at least 6 months. However, different IgG subclasses have different properties, and their roles in specific anti-COVID-19 responses have yet to be determined.

Primary Immunodeficiencies in Russia: Data From the National Registry.

Primary immunodeficiencies (PID) are a group of rare genetic disorders with a multitude of clinical symptoms. Characterization of epidemiological and clinical data via national registries has proven to be a valuable tool of studying these diseases. The Russian PID registry was set up in 2017, by the National Association of Experts in PID (NAEPID).