Humoral and Cellular Immune Response to SARS-CoV-2 S and N Proteins.

The pandemic of a new coronavirus infection that has lasted for more than 3 years, is still accompanied by frequent mutations in the S protein of SARS-CoV-2 and emergence of new virus variants causing new disease outbreak. Of all coronaviral proteins, the S and N proteins are the most immunogenic. The aim of this study was to compare the features of the humoral and T-cell immune responses to the SARS-CoV-2 S and N proteins in people with different histories of interaction with this virus. The study included 27 individuals who had COVID-19 once, 23 people who were vaccinated twice with the Sputnik V vaccine and did not have COVID-19, 22 people who had COVID-19 and were vaccinated twice with Sputnik V 6-12 months after the disease, and 25 people who had COVID-19 twice. The level of antibodies was determined by the enzyme immunoassay, and the cellular immunity was assessed by the expression of CD107a on CD8high lymphocytes after recognition of SARS-CoV-2 antigens. It was shown that the humoral immune response to the N protein was formed mainly by short-lived plasma cells synthesizing IgG antibodies of all four subclasses with a gradual switch from IgG3 to IgG1. The response to the S protein was formed by short-lived plasma cells at the beginning of the response (IgG1 and IgG3 subclasses) and then by long-lived plasma cells (IgG1 subclass). The dynamics of antibody level synthesized by the short-lived plasma cells was described by the Fisher equation, while changes in the level of antibodies synthesized by the long-lived plasma cells were described by the Erlang equation. The level of antibodies in the groups with the hybrid immunity exceeded that in the group with the post-vaccination immunity; the highest antibody content was observed in the group with the breakthrough immunity. The cellular immunity to the S and N proteins differed depending on the mode of immune response induction (vaccination or disease). Importantly, the response of heterologous CD8+ T cell to the N proteins of other coronaviruses may be involved in the immune defense against SARS-CoV-2.

Immunoglobulin G subclass profile of antimeasles response in vaccinated children and in adults with measles history.

The aim of this study was to investigate measles-specific immunoglobulin G (IgG) subclass profile in vaccinated children and in adults with natural infection. Serum samples were collected before and 30 days after vaccination. The sera from 51 late convalescent adults and seven adults with natural measles infection at the 12th day after onset of rash have been also investigated. Measles IgG antibodies and specific IgG subclasses were tested by enzyme-linked immunosorbent techniques. In children younger than 3 years, the predominant subclass was IgG3, which contributed, on average, 63.3% of the total IgG response. The contributions of specific IgG1 and IgG4 to the total IgG antimeasles response were lower (19.9% and 16.8%, respectively), whereas IgG2 was not found. In contrast, in the group of children older than 4 years, just IgG2 was a predominant subclass; it contributed 42.6% of the total IgG response. Other subclasses were also present but the contribution was much lower. In adult volunteers with measles history, IgG2 was a predominant subclass of total IgG. Thus, in early convalescence IgG2 contributed 62% of the total IgG response, whereas in late convalescence the contribution was lower (41.4%). There were no visible differences in IgG subclass composition between subjects with natural infection and vaccinated children except those below 3 years of age. The humoral immune response of such subjects is immature and the IgG2 subclass of virus-specific antibodies has not been revealed in the sera.

Cytokine profile after rubella vaccine inoculation: evidence of the immunosuppressive effect of vaccination.

BACKGROUND AND AIM: Immunization with live virus vaccines may cause an immunosuppression with lymphopaenia, impaired cytokine production and defective lymphocyte response to mitogenes. These abnormalities were described in subjects vaccinated against measles. This study was performed to analyse the host immune response related to immunosuppression in subjects vaccinated with live attenuated rubella vaccine. METHODS: Eighteen schoolgirls, aged 11-13 years, were vaccinated with live attenuated rubella vaccine Rudivax. Before immunization, and 7 and 30 days after, peripheral blood was collected. Cellular fractions were subjected to flow cytometric analysis, and the lymphocyte response to phytohaemagglutinin was investigated. Plasma samples were analysed for cytokines (interleukin (IL)-4, IL-10, tumour necrosis factor-alpha, and interferon-gamma) by enzyme-linked immunosorbent assay techniques. RESULTS: On day 7 after vaccination, the number of each lymphocyte subset was decreased; however, only for CD3 and CD4 lymphocytes has a significant reduction been shown. On the contrary, tumour necrosis factor-alpha and IL-10 levels markedly increased and amounted to its maximum on day 30. Simultaneously, a significant reduction in plasma interferon-gamma and a profound decrease of the lymphocyte response to phytohaemagglutinin were shown. The changes were accompanied with marked elevation of plasma IL-4. CONCLUSIONS: Our data indicate that the vaccination with live attenuated rubella vaccine results in moderate but sustained immune disturbance. The signs of immunosuppression, including defective lymphocyte response to mitogene and impaired cytokine production, may persist for at least 1 month after vaccination.