LAUSR

ABSTRACT Duck adenovirus 3 (DAdV-3) has been identified as the causative agent of a disease characterized by swelling and haemorrhages in liver and kidney of Muscovy ducks, causing huge economic losses to the waterfowl industry in China. In this study, a total of 54 DAdV-3 outbreaks from 2018 to 2020 in China were monitored with samples being collected and analyzed. The hexon amino acid sequences of the 54 DAdV-3 outbreaks and the DAdV-3 reference strains from GenBank were 98.7% to 100% identical. Epidemiological analysis showed that DAdV-3 circulated in meat-type and egg-laying Muscovy ducks, and co-infections with other viral and bacterial pathogens, such as Muscovy duck parvovirus (MDPV), Muscovy duck-origin goose parvovirus (MDGPV), adeno-associated virus (AAV), duck hepatitis B virus (DHBV), R. anatipestifer, and E. coli were identified. In addition, 12 out of the 23 (52.2%) DAdV-3 strains were isolated on LMH cells and identified by DAdV-3 real-time PCR. The whole-genome sequence analysis demonstrated that 12 new DAdV-3 isolates share 99.8–100% identity with the DAdV-3 reference strains, and nine new DAdV-3 isolates exhibit a truncated ORF67 gene. Our results enhance the understanding of the epidemiology and molecular characterization associated with DAdV-3 infection in China. RESEARCH HIGHLIGHTS First report of the epidemiology of duck adenovirus 3 infection in China. Mutant DAdV-3 strains (truncated ORF67) became predominant.