A Novel Chaphamaparvovirus Associated with Reduced Egg Production in Breeding Muscovy Ducks

Since 2022, a decrease in egg production and hatchability, along with hepatitis-like symptoms, has been frequently reported in Muscovy duck farms in southern China. Using metagenomic sequencing, a novel Chaphamaparvovirus (ChPV), designated MuChPV-GD2022, was identified in the livers of the diseased ducks. Phylogenetic analysis revealed that the MuChPV-GD2022 strain shares 61.8-77.4% genome identity with duck-origin Chaphamaparvoviruses, and 44.3-77.4% with avian-origin Chaphamaparvoviruses. The NS1 protein amino acid sequence showed a 29.3-71.5% similarity to those of other known Chaphamaparvoviruses. These findings support the classification of MuChPV-GD2022 as a new species in the genus Chaphamaparvovirus , family Parvoviridae . Since direct virus isolation was not achieved due to technical constraints, the evidence suggests MuChPV may be associated with the observed disease. Furthermore, a TaqMan qPCR assay targeting the NS1 gene was developed and validated for specificity, sensitivity, and repeatability. This assay provides a sensitive tool not only for virus detection but also for epidemiological surveillance of MuChPV infections.