WU Polyomavirus (WUPyV) is a small non‑enveloped DNA virus in the family Polyomaviridae. It was discovered in 2007 in samples of human respiratory secretions from a child in Australia and is classified as Betapolyomavirus quartihominis.
Background and Characteristics
WU polyomavirus was identified in 2007 by shotgun sequencing of nucleic acids from respiratory secretions in a child with pneumonia when other respiratory pathogens were not detected. The virus was named after Washington University in St. Louis, the institution of the researchers who described it. WUPyV is a non‑enveloped virus with an icosahedral capsid and a circular double‑stranded DNA genome of about 5,229 base pairs. The genome encodes the major capsid proteins VP1, VP2 and VP3 and two regulatory proteins, the large T antigen and small T antigen. Phylogenetic analysis places WUPyV in the genus Betapolyomavirus along with BK, JC and KI polyomaviruses. Early reports detected viral DNA in 0.7–3 % of respiratory samples from the United States and Australia, suggesting that active shedding is relatively infrequent. Serological surveys, however, show that antibodies to WUPyV are widespread; estimates of adult seroprevalence range from 69 % to more than 80 %, with evidence of maternal antibody transfer and primary infection during childhood. To date WUPyV has not been conclusively linked to disease. Although it was first isolated from a patient with pneumonia, subsequent studies often report high rates of co‑infection with other respiratory viruses and no clear causative role. Unlike some polyomaviruses, WUPyV has not been associated with cancer or nephropathy.
Occurrence and Serology Insights
WUPyV DNA has been detected in respiratory samples from children and adults across multiple continents, indicating a global distribution. In the initial study the virus was found in 0.7 % of samples from St. Louis and 3 % of samples from Brisbane. Follow‑up investigations in Europe and Asia have generally reported prevalence below 5 %. In contrast, antibody surveys reveal that exposure is very common; one U.S. cohort showed seropositivity in more than 97 % of adults. These data suggest that infection occurs early in life and that the virus persists at low levels. Genetically, WUPyV is closely related to KI polyomavirus, and both were discovered in 2007. Its regulatory region resembles that of other polyomaviruses, and the capsid proteins share conserved motifs. Because WUPyV is non‑enveloped, it exhibits environmental stability. Diagnostic detection relies on PCR amplification of viral DNA, and there are currently no specific antivirals or vaccines. Studies indicate that WUPyV does not replicate in the kidney or urinary tract, distinguishing it from BK virus. Weak evidence suggests that WU and KI polyomaviruses might have pathogenic potential in immunocompromised hosts, but this remains to be clarified. WU Polyomavirus is one of the more recently discovered human polyomaviruses. Despite its ubiquitous seroprevalence, there is no confirmed disease association, and it appears to establish persistent, asymptomatic infection in most people. Ongoing research will determine whether this widely distributed virus contributes to respiratory pathology under specific conditions. Related Terms: KI Polyomavirus, BK Virus, JC Virus, Merkel Cell Polyomavirus, Betapolyomavirus