Antibody Avidity Maturation Following Booster Vaccination with an Intranasal Adenovirus Salnavac Vaccine.

Background: The COVID-19 pandemic has led to the rapid development of new vaccines and methods of testing vaccine-induced immunity. Despite the extensive research that has been conducted on the level of specific antibodies, less attention has been paid to studying the avidity of these antibodies. The avidity of serum antibodies is associated with a vaccine showing high effectiveness and reflects the process of affinity maturation.

Antigenic Cartography of SARS-CoV-2.

Antigenic cartography is a tool for interpreting and visualizing antigenic differences between virus variants based on virus neutralization data. This approach has been successfully used in the selection of influenza vaccine seed strains. With the emergence of SARS-CoV-2 variants escaping vaccine-induced antibody response, adjusting COVID-19 vaccines has become essential.

Antigenic Cartography Indicates That the Omicron BA.1 and BA.4/BA.5 Variants Remain Antigenically Distant to Ancestral SARS-CoV-2 after Sputnik V Vaccination Followed by Homologous (Sputnik V) or Heterologous (Comirnaty) Revaccination.

The rapid emergence of evasive SARS-CoV-2 variants is an ongoing challenge for COVID-19 vaccinology. Traditional virus neutralization tests provide detailed datasets of neutralization titers against the viral variants. Such datasets are difficult to interpret and do not immediately inform of the sufficiency of the breadth of the antibody response.

Dissection of Antibody Responses of Gam-COVID-Vac-Vaccinated Subjects Suggests Involvement of Epitopes Outside RBD in SARS-CoV-2 Neutralization.

Millions of people have been vaccinated with Gam-COVID-Vac but fine specificities of induced antibodies have not been fully studied. Plasma from 12 naïve and 10 coronavirus disease 2019 (COVID-19) convalescent subjects was obtained before and after two immunizations with Gam-COVID-Vac. Antibody reactivity in the plasma samples (n = 44) was studied on a panel of micro-arrayed recombinant folded and unfolded severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) proteins and 46 peptides spanning the spike protein (S) and by immunoglobulin G (IgG) subclass enzyme-linked immunosorbent assay (ELISA).

High Heterogeneity of Virus-Neutralizing and RBD-Binding Activities of COVID-19 Convalescent Sera.

The parameters of the humoral response are an important immunological characteristic of donors who recovered from COVID-19 and vaccinated individuals. Analysis of the level of virus-binding antibodies has become widespread. The most accurate predictor of effective immune protection against symptomatic SARS-CoV-2 infection is the activity of virus-neutralizing antibodies.