Decoding cross-serotype interference in duck hepatitis viruses: Trivalent IgY targeting DHAV-1, DHAV-3 and DAstV-1.

To combat the emerging challenge of co-circulating hepatotropic pathogens, duck hepatitis A virus type 1 (DHAV-1), duck hepatitis A virus type 3 (DHAV-3), and Duck astrovirus type 1 (DAstV-1), complicating duck viral hepatitis (DVH) control in China, we engineered a novel trivalent egg yolk immunoglobulin (IgY) preparation designed to transcend serotype-specific limitations and enhance passive immunization efficacy. The polyvalent antibody was produced through multistage immunization protocols in high-yielding laying hens, followed by octanoic acid fractionation purification. The preparation exhibited a potent in vitro neutralization index of up to 1:143 against DHAV-1 and 1:256 against DHAV-3 while demonstrating robust immunoreactivity against the DAstV-1 antibody titer of 1:512 via ELISA. Prophylactic administration conferred complete protection (100 %) in challenge models. Therapeutic intervention yielded survival rates of 70 % for DHAV-1, 90 % for DHAV-3, and 80 % for DAstV-1. To our knowledge, this is the first report of a trivalent IgY agent that concurrently neutralizes the three predominant hepatotropic viruses (DHAV-1, DHAV-3, and DAstV-1) complicating DVH, establishing a broad-spectrum immunoprophylactic and therapeutic strategy.