Immunogenicity after CoronaVac vaccination

SUMMARY OBJECTIVE: This study aimed to investigate the seropositivity of CoronaVac-SinoVac vaccination in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) risk factors and comorbidities. METHODS: Immunoglobulin (IgG) antibody responses were examined on the 21st day after the second dose of CoronaVac-SinoVac 6 μg vaccine on the 28th day. SARS-CoV-2 IgG antibody levels were measured by using the enzyme-linked immunosorbent assay method in vaccinated health care workers (n=134) (Group I), vaccinated polymerase chain reaction (PCR) (+) who had coronavirus-19 (COVID-19) disease (n=21) (Group II), and unvaccinated PCR (+) (n=28) (Group III) participants. Subgroups were formed in Group I according to the presence of COVID-19 risk factors and comorbidities (diabetes mellitus, cardiovascular disease, and asthma/allergy) and demographic data. RESULTS: Seropositivity rates were 95.5, 100, and 89.3% for Groups I, II, and III, respectively. IgG antibody levels were found significantly higher in the group between the ages of 20-30 in group I compared to those aged 31-50 and over 50 (both p<0.01). It was found significantly higher in normal-weight individuals than in the overweight and obese group (both p<0.01). IgG antibody levels were found significantly lower in people with cardiovascular disease and diabetes mellitus compared with those who did not (p<0.05 and p<0.001, respectively). There was a negative correlation between IgG antibody response values and body mass index and age in Group I (r= −0.336, p<0.001 and r= −0.307, p<0.001, respectively). CONCLUSION: IgG antibody values decrease with age and with increasing body mass index. The presence of comorbidities (i.e., diabetes mellitus and cardiovascular disease) decreased COVID-19 IgG antibody values.

Expression of cell surface markers on methicillin resistant Staphylococcus aureus stimulated lymphocytes.

BACKGROUND & OBJECTIVE: Methicillin-resistant Staphylococcus aureus (MRSA) has gradually been increasing, new strategies in the treatment of MRSA infections are required. This depends on the understanding of the infection pathogenesis and the immune response. This study was therefore designed to determine the immune response which develops during MRSA infection and the role of chemokines in this response, and also to compare the results with the changes occurring after MSSA infection. METHODS: The expression of the surface markers of human lymphocytes stimulated by heat-killed MRSA or MSSA was analysed by flow cytometry. The chemokine levels in the lymphocytes culture supernatants stimulated or not stimulated by microorganisms were determined by ELISA. RESULTS: Human peripheral blood mononuclear cells (PBMCs) stimulated by MRSA the levels of CD4(+)CD25(+) regulatory T cells, CD69 expressions in the activated T lymphocytes, CD3(-)CD16(+)CD56(+) NK cells and the levels of MIP-1alpha, MIP-1beta, MCP-1 chemokines increased as compared to the cells not stimulated by MRSA. Although stimulation by MSSA caused an increase in CD25 expression after 24 h, the increase was found to be lower than the one caused by MRSA stimulation. The increase in CD69 expression was statistically significant compared to the cells stimulated by MRSA. Different from the cells stimulated by MRSA, no change was observed in the expressions of CD54 and CD3(-)CD16(+)CD56(+) NK cells in the cells stimulated by MSSA. INTERPRETATION & CONCLUSION: Our findings showed that cellular as well as humoral immunity are critical in MRSA infection and that T cell activation and the increase in chemokines may play a role in the regulation of immune response.