Circular RNA circPTPN3 facilitates duck hepatitis A virus type 3 (DHAV-3) infection by reducing miR-130b-5p function in duck.

Duck hepatitis A virus type 3 (DHAV-3) causes severe economic losses in the duck industry, yet the regulatory roles of circular RNAs (circRNAs) during infection remain unclear. This study combined transcriptome sequencing and functional analyses to investigate circRNA expression and mechanisms in DHAV-3 infection. We identified 44 differentially expressed circRNAs in duck livers post-infection, among which circPTPN3 was the most significantly upregulated. Gain- and loss-of-function experiments confirmed that circPTPN3 promotes DHAV-3 replication. Mechanistically, circPTPN3 was found to act as a sponge for miR-130b-5p, a miRNA with antiviral effects, thereby alleviating its suppression of pro-viral genes (e.g., ZC2HC1A, NMNAT2, and GPR65). These results reveal a novel circPTPN3/miR-130b-5p regulatory axis that facilitates DHAV-3 replication, providing new insights into host-virus interactions and potential therapeutic targets for antiviral strategies.