Cross-species characterization of feline parvovirus and Feline-Origin canine parvovirus Southern China (2023-2024): insights into epidemiology, genetic evolution and recombination.

Abstract

This study investigated the molecular evolution, co-circulation patterns, and potential risks of feline parvovirus (FPV) and canine parvovirus (CPV) in cats and dogs with gastrointestinal symptoms in Southern China from 2023 to 2024. A total of 356 rectal swab samples from cats and 301 from dogs were collected and tested by PCR (Polymerase chain reaction). The results showed that the positive rate of FPV in cats was 60.4%, and that of CPV in dogs was 50.8%. Viral isolation yielded 14 FPV strains from cats, 2 feline-derived CPV-2c strains, and 17 canine-derived CPV strains (including 11 CPV-2c, 4 CPV-2a, and 2 CPV-2b subtypes). Sequence analysis of the VP2 gene identified several novel amino acid mutations: in FPV strains, there were Gly31Ala, Ala300Gly, and Ala568Gly; in feline-derived CPV-2c strains, mutations included Ala5Gly, Pro495His, in canine-derived CPV strains included Glu318Pro/Asp323His/Asp505Lys, and Ala537Pro. Serial passage experiments of the feline-derived CPV2c-GD08-23 strain in CRFK cells (feline kidney cells) showed that a reversion mutation Gly568Ala occurred by the 16th passage, and the viral titer of the 16th passage was significantly lower than that of the 15th passage. Consistently, the average fluorescence intensity of the 16th passage in the IFA (Indirect immunofluorescence assay) was significantly lower than that of 15th passages. Recombination analysis identified four potential recombination events, suggesting possible genetic exchange between different viral strains. Structural prediction of the VP2 protein (including hydrophobicity and antigenic index analysis) revealed significant differences between the FPV strain GD06-23, feline-derived CPV-2c strains, and the vaccine reference strain (FPV-Italy-Pfizer-08). Tertiary structure modeling indicated that mutations such as Ala300Gly, Pro495His and Ala568Gly may alter the spatial conformation of the VP2 protein. Collectively, this study highlights novel evolutionary changes (mutations/recombination) in FPV and CPV that drive CPV adaptation to feline hosts, elevating its epidemiological risk in cats. The detection of feline-derived CPV-2c confirms the risk of cross-species transmission, providing insights for outbreak control.