The global distribution of canine parvovirus (CPV-2) derived from a closely related carnivore parvovirus poses a considerable threat to the dog population. The virus is continuously undergoing genetic evolution, giving rise to several variants. To investigate the prevalence of Chinese CPV-2 strains in recent years, a total of 30 CPV-2 strains were collected from 2018 to 2021 and the VP2 gene was sequenced and analyzed. Two variants, new CPV-2a (297Ala, 426Asn) and CPV-2c (426Glu), were identified. In contrast to previous reports, the CPV-2c variant has gained an epidemiological advantage over the new CPV-2a variant in China. To compensate for the relatively small sample size, 683 Chinese CPV-2 strains identified between 2014 and 2019 were retrieved from the GenBank database and previous publications, and analyses of these strains further supported our findings, which should be considered since the CPV-2c variant has been frequently associated with immune failure in adult dogs. VP2 protein sequence analysis revealed several amino acid substitutions, including Ala5Gly, Pro13Ser, Phe267Tyr, Tyr324Ile, Gln370Arg, Thr440Ala, and Lys570Arg. Phylogenetic analysis of full-length VP2 gene indicated a close relationship between Chinese strains and other Asian strains, suggesting mutual transmission between Asian countries. Furthermore, intercontinental transmission is a cause for concern. Surprisingly, two feline panleukopenia virus (FPV) strains with the Ile101Thr mutation in the VP2 protein were identified in canine fecal samples; FPV has been considered incapable of infecting dogs. This study clarified the epidemic characteristics of Chinese CPV-2 strains detected between 2014 and 2019, offering a reference for epidemic control. In addition, the detection of FPV in canine samples may provide information for future studies on the evolution of carnivore parvoviruses.

Outbreaks of short beak dwarf syndrome caused by novel goose parvovirus (NGPV) have been prevalent in China since 2015, resulting in a high mortality rate of ducks.Herein we evaluated differences between two NGPV strains: Muscovy duck-origin (AH190917-RP: MD17) and Cherry Valley duck-origin (JS191021-RP: CVD21) NGPV.Both of them showed certain level of pathogenicity to primary duck embryo fibroblasts, Cherry Valley duck embryos and ducklings. CVD21 showed comparatively stronger pathogenicity than MD17. Only CVD21 caused obvious cytopathic effect (CPE), characterized by cell shedding; further, the virus titer of MD17 and CVD21 was 10 2.571 ELD 50 (i.e. median embryo lethal dose)/0.2 ml and 10 6.156 ELD 50 /0.2 ml, respectively, and the mortality rate of CVD21-and MD17-infected Cherry Valley ducklings was 100% and 80%, respectively. In addition, CVD21 had a greater influence on the growth and development of ducklings. Furthermore, we found that MD17 could infect Muscovy duck embryos and produce lesions similar to Cherry Valley duck embryos, but it could not infect Muscovy duck embryo fibroblasts (MDEFs,) and Muscovy ducklings.MDV21 had no infection to MDEFs, Muscovy duck embryo and Muscovy ducklings. We then sequenced the complete genome of the two isolates to enable genomic characterization. The complete genome of MD17 and CVD21 was 5046 and 5050 nucleotides in length, respectively. Nucleotide alignment, amino acid analysis and phylogenetic tree analysis revealed that MD17 showed higher homology to goose parvovirus (GPV), while CVD21 demonstrated stronger similarity with NGPV. Moreover, the two isolates shared 95.8% homology, with encoded proteins showing multiple amino acid variations. Our findings indicate that Muscovy ducks seem to have played a crucial role in the evolution of GPV to NGPV. We believe that our data should serve as a foundation for further studying the genetic evolution of waterfowl parvoviruses and their pathogenic mechanisms.