Cytopathic Effect and Morphogenesis of WUPyV in Human Airway Epithelial Cells.

Washington University polyomavirus (WUPyV), a member of the polyomavirus family capable of infecting the human respiratory tract, exhibits high prevalence in human populations. However, confirmation of its pathogenicity and aetiology has been hindered by challenging culture conditions. To investigate the infective endocytosis of WUPyV, a novel infection model was developed using human airway organoids (HAOs); viral replication dynamics, cell tropism, endocytosis mechanisms, and morphogenesis in human airway epithelium (HAE) were characterized. The results indicated that WUPyV replicates efficiently and infects multiple cell types within the respiratory epithelium. After JC polyomavirus, WUPyV is the second human polyomavirus known to enter cells via clathrin-mediated endocytosis, independent of caveolar/lipid raft-mediated endocytosis or macropinocytosis. Consistent with other polyomaviruses, WUPyV is transported to the nucleus for replication and assembly through a lipid-dependent pathway requiring tyrosine kinase activity and endosome/lysosome acidification. Assembled viral particles were observed in nuclear pores; they were ultimately released extracellularly through vesicles and schistocytes. High-titre WUPyV infection caused extensive structural damage to the HAE and its cilia. Our findings provide important insights into the endocytosis, morphogenesis, and ultrastructural damage induced by WUPyV, supporting the notion that WUPyV is an underestimated human pathogen.