Heat shock protein 90α mediates endocytosis of duck hepatitis a virus type 3 (DHAV-3) via interaction with viral capsid protein 1

Duck hepatitis A virus type 3 (DHAV-3) causes acute fatal hepatitis in ducklings, yet the molecular basis of host susceptibility remains poorly understood. Using ducklings selectively bred for natural resistance or susceptibility to DHAV-3, we reanalyzed single-cell transcriptomic data, identified endocytosis as a key pathway in infected hepatocytes, and found that HSP90AA1 (encoding heat shock protein 90α) was differentially expressed between resistant and susceptible hosts. Functional assays revealed that knockdown or pharmacological inhibition of HSP90AA1 did not affect viral adsorption but significantly impaired viral entry, indicating that HSP90AA1 mediates viral endocytosis. Mechanistically, DHAV-3 enters cells via clathrin-mediated, dynamin-independent endocytosis. The viral capsid protein VP1 directly binds to cell-surface HSP90AA1, and this interaction is required for efficient viral internalization. Collectively, these results establish HSP90AA1 as a key mediator of DHAV-3 endocytosis and a functional entry receptor, with its differential expression between susceptible and resistant hosts correlating with the observed disparity in viral susceptibility. This study provides new insights into host-picornavirus interactions and highlights HSP90AA1 as a potential target for antiviral intervention against DHAV-3 infection.