Human polyomavirus 9 (HPyV9) was originally detected in the serum of a renal transplant patient. Seroepidemiological studies showed that ~20-50% of the human population have antibodies against this virus. HPyV9 has not yet been associated with any disease and little is known about the route of infection, transmission, host cell tropism, and genomic variability in circulating strains. Recently, the ...