Genetic and antigenic characterization of classical and recombinant waterfowl parvoviruses circulating in Taiwan

Parvovirus infections are highly communicable and pathogenic in ducklings and goslings, leading to major economic losses in waterfowl farming. Although it is well established that Goose parvovirus (GPV) and Muscovy duck parvovirus (MDPV) are primary causes of disease, control of these viruses is difficult due to cross-species transmission and high infectivity of variant strains derived from viral recombination and mutation. In this study, we performed molecular and antigenic analyses on ten field-derived waterfowl parvovirus isolates collected between 2019 and 2023. Phylogenetic analysis of these isolates showed that classical GPVs, classical MDPVs and recombinant MDPVs (rMDPVs) were simultaneously present in the fields of Taiwan. Moreover, Taiwanese rMDPV isolates were highly similar to strains isolated in mainland China in terms of nucleic and amino acid sequences. To understand the antigenic relationships between the field isolates and a standard GPV vaccine strain, viral cross-neutralizing tests were performed. As expected, classical GPVs and MDPVs were antigenically different from each other, while the rMDPV isolates showed a closer antigenic relationship with GPV than with MDPV. Although the VP1 amino acid sequences were 91% identical between the GPV vaccinal strain (82-0321V) and rMDPVs isolates, we found that the GPV vaccinal strain and rMDPV were antigenically different subtypes. Molecular traceability assays searching the VP1 genes in GenBank demonstrated that the most recent common ancestor of waterfowl parvoviruses may have appeared in the 1830s, and rMDPV was likely derived from MDPV around the 1900s. Furthermore, the rMDPVs exhibited a higher estimated evolutionary rate than typical waterfowl parvoviruses. Taken together, our results reveal three distinct types of waterfowl parvoviruses in the fields of Taiwan. The viruses show genetic and antigenic differences, and were likely introduced at different times. These findings suggest that further molecular epidemiologic and antigenic investigations may help to improve waterfowl parvovirus control.