ASSESSMENT OF SARS-COV-2 SPECIFIC B-CELL IMMUNE MEMORY: EVIDENCE FOR PERSISTENCE UP TO 1 YEAR POST-INFECTION

Background: SARS-CoV-2, the virus responsible for COVID-19 pandemic, has posed huge global health challenges. Understanding the immune response to SARS-CoV-2 infection, and in particular – the role of B cells in the generation of immune memory is crucial for assessing the durability of protective immunity. Materials and Methods: In this longitudinal prospective study, individuals who had recovered from SARS-CoV-2 infection were included. Peripheral venous blood samples were collected at three time intervals post symptom onset (PSO): 1-3 mo, 4-8 mo, and 9-12 mo. The humoral immune response was evaluated by measuring anti-SARS-CoV-2 IgG, virus-neutralizing antibody activity, total S1-specific B-cells, and B cell subpopulations. Results: The levels of anti-SARS-CoV-2 specific IgG antibodies decreased from 390.3 to 204.5 BAU/ml in the first 6-8 months PSO but did not significantly decrease further until the 12 th mo (126.6 BAU/ml). Virus-neutralizing antibodies (activity decreased by 20.4% between the 1st and 6-8th mos but remained relatively stable thereafter and could be detected up to 12 months PSO. In peripheral blood, the amount of S1-specific plasmablasts was highest one month after COVID-19 infection, and the level of memory B cells at 6 months. Those were detected even 12 months PSO, albeit in smaller quantities.  Conclusion: The study provides evidence for the persistence of SARS-CoV-2-specific B-cell immune memory up to 1year post-infection. The presence of virus-specific memory B cells and plasmablasts suggests potential for sustained protection against reinfection. Further research is needed to elucidate the role of B-cell immune memory in preventing infection and to understand the individual variations of immune response.