DNA and seroprevalence study of MW and STL polyomaviruses.

The clinical importance and the pathogenesis of the MW and STL polyomaviruses (PyVs) remain unclear. Our aim was to study the seroprevalence of MWPyV and STLPyV, and to examine the prevalence of viral DNA in respiratory samples and secondary lymphoid tissues. In total, 618 serum samples (0.8-90 years) were analyzed for seroprevalence. For the DNA prevalence study, 146 patients (2.5-37.5 years) were sampled for adenoids (n = 100), tonsils (n = 100), throat swabs (n = 146), and middle ear discharge (n = 15) in study Group 1. In Group 2, we analyzed 1130 nasopharyngeal samples from patients (0.8-92 years) tested for SARS-CoV-2 infection. The adult seropositivity was 54% for MWPyV, and 81.2% for STLPyV. Both seroprevalence rates increased with age; however, the majority of STLPyV primary infections appeared to occur in children. MWPyV was detected in 2.7%-4.9% of respiratory samples, and in a middle ear discharge. STLPyV DNA prevalence was 1.4%-3.4% in swab samples, and it was detected in an adenoid and in a middle ear discharge. The prevalence of both viruses was significantly higher in the children. Noncoding control regions of both viruses and the complete genomes of STLPyV were sequenced. MWPyV and STLPyV are widespread viruses, and respiratory transmission may be possible.