Molecular characterisation of the current high prevalence of the new CPV-2c variants in the Southern Vietnamese dogs signifies a widespread in the worldwide dog population.

BACKGROUND

Canine parvovirus type 2 (CPV-2) is known as the primary etiological agent cause of acute gastroenteritis, myocarditis and death of canids worldwide. In Vietnam, although CPV-2 infection and its outbreaks are the most important risk factors of the canine's health concern, lack of available information about the molecular epidemiology of the CPV-2.

OBJECTIVES

In this study, the complete coding sequences of 10 CPV-2 strains collected from dogs vaccinated with CPV-2 vaccination were analysed to better understand the genomic characteristics of the current circulating CPV-2 in Vietnam.

METHODS

Ten CPV-specific PCR-positive rectal swab samples were collected from dogs with acute symptoms of haemorrhagic diarrhoea and vomiting in Vietnam in 2019. The complete coding sequences of these CPV strains were analysed to determine their phylogeny and genetic relationship with other available CPV strains globally.

RESULTS

Analysis of the VP2 gene sequences demonstrated that the studied strains belonged to the new CPV-2c variants with the unique mutations at amino acids 5 and 447 . Phylogenetic tree analysis indicated that the studied strains share a common evolutionary origin with the current CPV-2c strains circulating in dogs in Asia countries, including China, Thailand, Taiwan and Mongolia, in recent years. Low sequence identity between the studied strains and commercial vaccine strains was observed.

CONCLUSIONS

This study provides deep insights into the molecular characteristics, genetic diversity, and evolution of circulating CPV-2 strains in Vietnam. We recommend more studies to estimate the effectiveness of the CPV vaccine and the need to continue developing other effective vaccination essential to better control the widespread of these new CPV-2 variants.