Molecular epidemiology and characterization of goose polyomavirus in China: insights into its impact on hatchability and susceptibility to co-infections

Introduction Goose hemorrhagic polyomavirus (GHPV) is the primary etiological agent of goose hemorrhagic nephritis and enteritis (HGNE), a disease causing substantial economic losses to the global waterfowl industry. Despite documented outbreaks in Europe and Asia, integrated molecular epidemiological evidence linking clinical outbreaks, co-infections, and viral phylogeny remains limited. Methods We conducted nationwide epidemiological surveillance across eight provinces in China from March 2023 to April 2025, covering 83 farms and 1,902 samples. An outbreak of reduced hatchability was investigated via PCR screening for nine common waterfowl pathogens and bacteriological culture. Virus isolation was performed using embryos from multiple goose breeds, followed by full-genome sequencing and comparative molecular characterization of the isolates. Results GHPV was detected in 49% (41/83) of surveyed farms, with an overall individual prevalence of 4% (84/1902). No co-infections were observed in goslings or embryos, but a high co-infection rate of 75% (27/36) was found in GHPV-positive adult geese, with Goose circovirus (GoCV) as the most frequent co-infecting agent (93%). Experimental inoculation showed that Landes goose embryos and their derived primary cells were highly susceptible to GHPV replication, whereas Sichuan White and Sanhua Hybrid geese were not permissive, indicating breed-dependent host–virus interactions. The Chinese isolates exhibited high genomic conservation, with VP1 gene nucleotide homology ranging from 98.3% to 100% among global strains. Discussion The combination of low overall prevalence, high co-infection rate in adults, and marked genomic conservation suggests that GHPV may act as an opportunistic pathogen, whose clinical impact is amplified through synergistic interactions with co-infecting agents, particularly GoCV. These findings highlight the need for integrated surveillance targeting co-circulating pathogens and underscore the importance of breed-specific considerations in hatchery management and disease control strategies.