Molecular characteristics and genetic evolutionary analyses of circulating parvoviruses derived from cats in Beijing

Abstract

Background: Feline parvovirus (FPV) is a member of the family Parvoviridae, which is a major enteric pathogen of cats worldwide. This study aimed to investigate the prevalence of feline parvovirus in Beijing of China and analyze the genetic features of detected viruses.

Results: In this study, a total of 60 (8.5%) parvovirus-positive samples were detected from 702 cat fecal samples using parvovirus-specific PCR. The complete VP2 genes were amplified from all these samples. Among them, 55 (91.7%) sequences were characterized as FPV, and the other five (8.3%) were typed as canine parvovirus type 2 (CPV-2) variants, comprised of four CPV-2c and a new CPV-2b strain. In order to investigate the origin of CPV-2 variants in cats, we amplified full-length VP2 genes from seven fecal samples of dogs infected with CPV-2, which were further classified as CPV-2c. The sequences of new CPV-2b/MT270586 and CPV-2c/MT270587 detected from feline samples shared 100% identity with previous canine isolates KT156833 and MF467242 respectively, suggesting the CPV-2 variants circulating in cats might be derived from dogs. Sequence analysis indicated new mutations, Ala91Ser and Ser192Phe, in the FPV sequences, while obtained CPV-2c carried mutations reported in Asian CPV variants, showing they share a common evolutionary pattern with the Asian 2c strains. Interestingly, the FPV sequence (MT270571), displaying four CPV-specific residues, was found to be a putative recombinant sequence between CPV-2c and FPV. Phylogenetic analysis of the VP2 gene showed that amino acid and nucleotide mutations promoted the evolution of FPV and CPV lineages.

Conclusions: Our findings will be helpful to further understand the circulation and evolution of feline and canine parvovirus in Beijing.

Keywords: Canine parvovirus (CPV); Evolution; Feline parvovirus (FPV); Recombination; VP2 gene.

Fig. 1

Maximum-likelihood tree showing the genetic relationship of the full-length VP2 gene of feline parvovirus and canine parvovirus strains. Maximum‐likelihood (ML) tree based on 112 full‐length VP2 sequences of FPV, CPV and MEV strains. The tree was constructed using the T92 + G model and 1,000 bootstrapping with MEGAX software. Mink enteritis virus (MEV) was used as the outgroup. Bootstrap values (%) greater than 50 are shown. Sequences used in this analysis are indicated with their respective virus type (FPV/CPV/MEV) or variant (CPV-2/2a/2b/2c, new CPV-2a/2b), country and year of collection, origin, and GenBank accession number. FPV sequences detected in this study are indicated by black dots and CPV sequences from cats and dogs are indicated by red dots and black triangles, respectively. The recombinant FPV sequence MT270571 was shown in red

Fig. 2

Schematic diagram of the naturally recombinant FPV/MT270571 sequence. CPV-2c/KT156832 isolated in China and FPV/MK570646 from Australia served as the putative major and minor parents. A The potential recombination event was detected in the VP2 protein gene and was supported by similarity (2A) and bootscan (2B) analysis, which indicated that CPV-2c/KT156832 (red line) served as the main template of the complete VP2 gene, and the beginning of the VP2 gene was replaced by FPV/MK570646 (blue line). The FPV/MT270571 sequence served as the query. The y-axis indicated the percentage of nucleotide identity and permutated trees for the similarity plot and boot scanning, respectively, within a 200 bp-wide window with a 20-bp step size between plots. B The ML phylogenetic trees of the recombinant MT/270571 strains (♦) and it's major (▲) and minor (▼) putative parent strains over nucleotides 1–1,129 (2C) and 1,130–1,755 (2D). Bootstrap (1000 replications) values over 50% are shown for each node