Co-Circulation of the Rare CPV-2c with Unique Gln370Arg Substitution, New CPV-2b with Unique Thr440Ala Substitution, and New CPV-2a with High Prevalence and Variation in Heilongjiang Province, Northeast China.

Yufei Geng,Li Feng,Chunqiu Li,Rui Wu,Shuang Yao,Dongbo Sun,Jianfa Wang,Mingjun Su,Enyu Wang,Xiwen Zhao,Donghua Guo,Shan Wei,Zhihui Wang,Xinyu Wang

doi:10.1371/journal.pone.0137288

Abstract

To trace evolution of canine parvovirus-2 (CPV-2), a total of 201 stool samples were collected from dogs with diarrhea in Heilongjiang province of northeast China from May 2014 to April 2015. The presence of CPV-2 in the samples was determined by PCR amplification of the VP2 gene (568 bp) of CPV-2. The results revealed that 95 samples (47.26%) were positive for CPV-2, and they showed 98.8%–100% nucleotide identity and 97.6%–100% amino acid identity. Of 95 CPV-2-positive samples, types new2a (Ser297Ala), new2b (Ser297Ala), and 2c accounted for 64.21%, 21.05%, and 14.74%, respectively. The positive rate of CPV-2 and the distribution of the new2a, new2b and 2c types exhibited differences among regions, seasons, and ages. Immunized dogs accounted for 48.42% of 95 CPV-2-positive samples. Coinfections with canine coronavirus, canine kobuvirus, and canine bocavirus were identified. Phylogenetic analysis revealed that the identified new2a, new2b, and CPV-2c strains in our study exhibited a close relationship with most of the CPV-2 strains from China; type new2a strains exhibited high variability, forming three subgroups; type new2b and CPV-2c strains formed one group with reference strains from China. Of 95 CPV-2 strains, Tyr324Ile and Thr440Ala substitutions accounted for 100% and 64.21%, respectively; all type new2b strains exhibited the Thr440Ala substitution, while the unique Gln370Arg substitution was found in all type 2c strains. Recombination analysis using entire VP2 gene indicated possible recombination events between the identified CPV-2 strains and reference strains from China. Our data revealed the co-circulation of new CPV-2a, new CPV-2b, and rare CPV-2c, as well as potential recombination events among Chinese CPV-2 strains.

Highlights

Canine parvovirus-2 (CPV-2) causes a highly contagious and often fatal disease characterized by vomiting and hemorrhagic gastroenteritis in dogs of all ages, and by myocarditis in pups of less than three months of age [1]
A total of 201 samples from the Harbin, Daqing, and Mudanjiang districts of Heilongjiang province in northeast China were detected via polymerase chain reaction (PCR) amplification of 568 bp of the VP2 gene of CPV-2
Residue 324Ile was present in all 95 CPV-2-positive samples when compared with the reference strains, and residue 370Arg was specific for type CPV-2c when compared with CPV-2c reference strains

Summary

Introduction

Canine parvovirus-2 (CPV-2) causes a highly contagious and often fatal disease characterized by vomiting and hemorrhagic gastroenteritis in dogs of all ages, and by myocarditis in pups of less than three months of age [1]. The vaccine could provide protective immunity against the classic CPV-2 infection in canine populations, reducing the mortality of animals and spreading of the virus. VP2 is widely used for the identification and monitoring of the types of CPV-2 circulating in the canine population based on the amino acid residues of the VP2 protein at positions 426Asp/ Glu/Asn and 297Ser/Ala [10, 12,13,14,15]. The molecular epidemiology of the CPV-2 strains circulating in northeast China was investigated by polymerase chain reaction (PCR) targeting the partial VP2 gene. Our aim was to provide insights into the epidemiology and genetic diversity of the CPV-2 strains circulating in northeast China, which can be useful for preventing and controlling CPV-2 infections

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Conclusion