BK polyomavirus in a Portuguese healthy group: seroprevalence, viral Excretion, and implications for transmission pathways.

PURPOSE: The present study aimed to: characterize BK polyomavirus (BKPyV) infection in a group of a Portuguese healthy individuals by evaluating its seroprevalence and urinary excretion; and to contribute to the elucidation of BKPyV transmission routes by assessing its genome in respiratory and vaginal secretions.

METHODS

Different types of biological samples from healthy Portuguese individuals were used in this study. The presence of BKPyV-specific IgG antibodies was evaluated in 83 serum samples trough ELISA methodology. BKPyV DNA was assessed in 123 urines, 574 nasopharyngeal and oropharyngeal secretions, and 293 vaginal secretions by real-time PCR.

RESULTS

BKPyV antibodies were detected in 78.3% of the studied healthy adults, with a slight decrease observed with age. BKPyV DNA was detected in urine of 17.9% of the evaluated individuals (median BKPyV-load 2.34 log copies/mL). The frequency of BKPyV genome in urine increased with age, with values of 7.5% among children and 22.9% among adults (p = 0.045). BKPyV DNA was detected in one nasopharyngeal secretion (0.2%), and three vaginal exudates (1.0%).

CONCLUSION

The obtained seroprevalence data supports the hypothesis of a primary infection during the first years of life, followed by a waning of antibodies in older individuals. BKPyV urinary excretion was detected in seronegative individuals, which may represent primary infections or be associated with a age-related loss of antibodies. Regarding BKPyV transmission, nasopharyngeal secretions are unlikely to be implicated, whereas vaginal secretions may represent a potential source or site of transmission.