Molecular epidemiology and humoral immunity of BK polyomavirus in the general population of Southern China.

OBJECTIVES

This study investigates the molecular epidemiology and BKPyV-specific immune responses in a healthy population to elucidate the infection dynamics of this ubiquitous virus.

METHODS

A cross-sectional study was conducted on 2543 healthy individuals (aged 1 day to 94 years). Urinary BKPyV DNA was quantified by qPCR, and genotypes were determined by VP1 gene sequencing. BKPyV genotype 1-b1 VP1-specific antibodies levels in urine and serum were measured by ELISA.

RESULTS

Urinary BKPyV DNA positivity exhibited a bimodal age distribution: 10.1-10.4% in children (5-14 years) and 34.1% in individuals over 70. Serum and urine anti-BKPyV-IgA levels showed a similar age distribution. In contrast, IgG and IgM antibody levels showed a different age distribution. ROC analysis indicated that serum and urine anti-BKPyV-IgA demonstrated superior performance in predicting urinary BKPyV DNA positivity compared to anti-BKPyV-IgG and anti-BKPyV-IgM. Genotypes I (subtypes I-b1 and I-c) and IV were identified, with genotype I being the most prevalent. BKPyV-specific antibody levels in urine and serum were positively correlated. Anti-BKPyV-IgG2, -IgG3, and -IgA1 subclasses were predominant in both compartments.

CONCLUSIONS

This study characterizes aspects of the systemic and mucosal humoral immune response to BKPyV infection, offering preliminary insights into immunity in the general population.