JC and BK polyomavirus-specific immunoglobulin G responses in patients thymectomized in early childhood

BACKGROUND: JC (JCPyV) and BK polyomaviruses (BKPyV) infect 50-90% of the general population and thereafter persist with asymptomatic shedding. Previous studies have revealed a delayed antibody response to neo-antigens in children and adolescents who were thymectomized due to congenital heart defects. OBJECTIVES: The present longitudinal study aimed at analyzing the seroprevalence and the antibody persistence against BKPyV and JCPyV in a 3-years time period in thymectomized patients (TP) compared to healthy controls (HC). STUDY DESIGN: Given the widespread primary and secondary exposure to BKPyV and JCPyV, we examined the impact of childhood thymectomy on specific IgG levels by ELISA using the respective virus-like particles. RESULTS: IgG-anti-BKPyV levels which were lower at beginning of the study increased in TP after a 3-years time interval and correlated with age. In contrast, IgG-anti-BKPyV levels decreased in HC within the same time period. Individuals losing humoral immunity against BKPyV and JCPyV were seen in both TP and HC. CONCLUSIONS: Although seroprevalence and maintenance of antibodies against BKPyV and JCPyV were similar between TP and HC, a more dynamic process was suggested for TP, with a probably delayed humoral immune response in some patients but similar waning of antibodies compared to HC. Our study supports the hypothesis that in thymectomy, similar to vaccination, antibody responses to neo-antigens are delayed. The assessment of long-term antibody stability together with cellular reactivity and detection of viremic episodes will elucidate further aspects of controlling of persistent viral infections in thymectomized individuals and the role of a complete thymus.