COVID-19 caused by SARS-CoV-2 is continuing to spread around the world and drastically affect our daily life. New strains appear, and the severity of the course of the disease itself seems to be decreasing, but even people who have been ill on an outpatient basis suffer post-COVID consequences. Partly, it is associated with the autoimmune reactions, so debates about the development of new vaccines and the need for vaccination/revaccination continue. In this study we performed an analysis of the antibody response of patients with COVID-19 to linear and conformational epitopes of viral proteins using ELISA, chip array and western blot with analysis of correlations between antibody titer, disease severity, and complications. We have shown that the presence of IgG antibodies to the nucleoprotein can deteriorate the course of the disease, induce multiple direct COVID-19 symptoms, and contribute to long-term post-covid symptoms. We analyzed the cross reactivity of antibodies to SARS-CoV-2 with own human proteins and showed that antibodies to the nucleocapsid protein can bind to human proteins. In accordance with the possibility of HLA presentation, the main possible targets of the autoantibodies were identified. People with HLA alleles A01:01; A26:01; B39:01; B15:01 are most susceptible to the development of autoimmune processes after COVID-19.

Mutations in surface proteins enable emerging variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) to escape a substantial fraction of neutralizing antibodies and may thus weaken vaccine-driven immunity. To compare available vaccines and justify revaccination, rapid evaluation of antibody (Ab) responses to currently circulating SARS-CoV-2 variants of interest (VOI) and concern (VOC) is needed. Here, we developed a multiplex protein microarray-based system for rapid profiling of anti-SARS-CoV-2 Ab levels in human sera. The microarray system was validated using sera samples from SARS-CoV-2-free donors and those diagnosed with COVID-19 based on PCR and enzyme immunoassays. Microarray-based profiling of vaccinated donors revealed a substantial difference in anti-VOC Ab levels elicited by the replication-deficient adenovirus vector-base (Sputnik V) and whole-virion (CoviVac Russia COVID-19) vaccines. Whole-virion vaccine-induced Abs showed minor but statistically significant cross-reactivity with the human blood coagulation factor 1 (fibrinogen) and thrombin. However, their effects on blood clotting were negligible, according to thrombin time tests, providing evidence against the concept of pronounced cross-reactivity-related side effects of the vaccine. Importantly, all samples were collected in the pre-Omicron period but showed noticeable responses to the receptor-binding domain (RBD) of the Omicron spike protein. Thus, using the new express Ab-profiling system, we confirmed the inter-variant cross-reactivity of the anti-SARS-CoV-2 Abs and demonstrated the relative potency of the vaccines against new VOCs.

Whooping cough is a serious illness affecting young children. There are two main types of vaccines for whooping cough: cellular and acellular. We focused on studying the immune response to Bordetella pertussis based on the type of vaccination to uncover factors that affect vaccine effectiveness. It is worth noting that the immune response to Bordetella pertussis depends on many factors. In this study, we examine the role of the systemic T cell response. It was found that memory T cells react to components of the pertussis bacterium, and the strength of this response is independent of the vaccination type. In most donors, the T cell response to the inactivated bacterium was more robust than to gd15PtxS1 (genetically detoxified S1 subunit of pertussis toxin), a key ingredient in acellular vaccines. This indicates the existence of dominant epitopes beyond PT that elicit an immune response. Additionally, a bioinformatics analysis was conducted on the epitopes of various B. pertussis proteins, predicting their dominance based on HLA alleles and assessing the potential for cross-reactive T cell responses to other Bordetella species and human microbiota. These findings could help in the development of new vaccines against B. pertussis or in modifying existing vaccines to improve their efficacy and minimize side effects. These results may help in the development of new vaccines against B. pertussis or in the modification of vaccines to their efficacy and minimize side effects.

Гуморальный иммунный ответ на линейные и конформационные эпитопы SARS-CoV-2 у пациентов с COVID-19

Bordetella pertussis, a gram-negative bacterium responsible for whooping cough, poses severe health risks, especially to young children. However, the disease can be prevented by immunization with whole-cell pertussis vaccines and acellular pertussis vaccines containing 2–5 purified B. pertussis antigens, of which chemically detoxified pertussis toxin is the main protective component. While current vaccines have proven effective, concerns over high reactogenicity of whole-cell pertussis vaccines and the waning immunity to acellular pertussis vaccines formulations underscore the need for improved pertussis vaccines. Genetically detoxified pertussis toxin is an attractive vaccine candidate because it retains most of the structural properties of native pertussis toxin and better preserves the protective epitopes compared to detoxified pertussis toxin. In this study, we developed a candidate vaccine based on a genetically detoxified pertussis toxin S1 subunit, gd15PTxS1. We evaluated humoral and cellular immunogenicity of gd15PTxS1 in a murine model and demonstrated significant anti-PTx IgG seroconversion and a balanced Th1/Th2/Th17 T-cell response, with gd15PTxS1 inducing robust cytotoxic and helper T-cell activation comparable to that of the whole-cell pertussis vaccines. Our results show that gd15PTxS1 is highly immunogenic in mice and is a promising vaccine candidate for further protectivity studies.

Bordetella pertussis elicits both innate and adaptive cellular responses, yet their relative contribution to peripheral IFN-γ measurements and the temporal behavior of circulating T-cell immunity in adults remain incompletely defined. We investigated B. pertussis-reactive cellular immunity in peripheral blood in healthy and convalescent adult donors using IFN-γ ELISpot assays after stimulation with whole-cell B. pertussis or bacterial components (LPS and B. pertussis-derived LOS), and HLA-A02 genotyping. Short-term stimulation of unfractionated PBMCs produced a prominent IFN-γ response that was not clearly associated with previous vaccination or pertussis history. LOS and LPS induced strong responses in PBMCs but little detectable IFN-γ secretion by T cells, whereas whole-cell B. pertussis retained T-cell-associated IFN-γ response. Circulating B. pertussis-reactive T-cell responses were highest after recovery, declined substantially within approximately 3 months, and approached baseline by ≥1 year. CD8+ IFN-γ responses were preferentially detected in HLA-A*02-positive donors. These findings indicate that adult peripheral immunity to B. pertussis comprises cellularly and temporally distinct IFN-γ-producing components and that cellular context, time after infection, and HLA class I genotype influence their detection and interpretation.