Identification and P1 Genetic Evolutionary Analysis of Duck Hepatitis A Virus Type 3 in Selected Areas of Jiangsu, China in 2024

Duck hepatitis A virus type 3 (DHAV-3) is a widespread, highly lethal pathogen in East Asian ducklings. To investigate its molecular characteristics in Jiangsu, China, we performed PCR on 103 liver samples from deceased ducklings and isolated 14 DHAV-3 strains. Phylogenetic analysis of P1, VP0, VP3 , and VP1 , showing that the isolates shared more than 95.1% of nucleotide identities and more than 98.3% of amino acid identities, indicated close phylogenetic relationships among the isolates. Compared with reference strains, the isolates shared a high identity with strains from Shandong, Anhui, Chongqing, and Henan Provinces, but a lower identity with strains from South Korea and Vietnam, which suggests distinct geographical clustering. Phylogenetic analysis also confirmed that all isolates clustered into GI and were distinct from South Korean and Vietnamese strains in GII, thereby indicating significant genetic divergence. Meanwhile, genetic variation analysis of VP1 and protein structure prediction for the isolates revealed amino acid mutations at positions 141 and 190 in some isolates, and at positions 141 and 207 in certain reference strains, which correlated with phylogenetic relationships. The three-dimensional structure of the VP1 protein was conserved overall, with localized alterations in mutated regions. Altogether, DHAV-3 strains in Jiangsu showed high genetic conservation but distinct geographical clustering, and the identified VP1 variations warrant further investigation. This article elucidated DHAV-3’s molecular characteristics in Jiangsu and provided critical data for tracking viral evolution and updating regional vaccine strategies.