Pathogenesis and phylogenetic analyses of canine distemper virus strain ZJ7 isolate from domestic dogs in China

Bin Tan,Hua Wu,Xiu-Dong Wang,Xin-Chuan Shi,Jia-Xin Hu,Shi-Peng Cheng,Li-Zhi Chen,Yong-Jun Wen,Shu-Qin Zhang,Feng-Xue Wang,Bo-Chao Yang

doi:10.1186/1743-422x-8-520

Abstract

A new isolate of canine distemper virus (CDV), named ZJ7, was isolated from lung tissues of a dog suspected with CDV infection using MDCK cells. The ZJ7 isolate induced cytopathogenic effects of syncytia in MDCK cell after six passages. In order to evaluate pathogenesis of ZJ7 strain, three CDV sero-negative dogs were intranasally inoculated with its virus suspension. All infected dogs developed clinical signs of severe bloody diarrhea, conjunctivitis, ocular discharge, nasal discharge and coughing, fever and weight loss at 21 dpi, whereas the mock group infected with DMEM were normal. The results demonstrated that CDV-ZJ7 strain isolated by MDCK cell was virulent, and the nucleotide and amino acid sequences of strain ZJ7 had no change after isolation by MDCK cell when compared with the original virus from the fresh tissues. Molecular and phylogenetic analyses for the nucleocapsid (N), phosphoprotein (P) and receptor binding haemagglutinin (H) gene of the ZJ7 isolate clearly showed it is joins to the Asia 1 group cluster of CDV strains, the predominant genotype in China.

Highlights

Canine distemper (CD) is an acute or subacute, highly contagious disease with signs of generalized infection including respiratory disease, foot pad hyperkeratosis, central nervous system disturbance or a combination of these symptoms [1]
In this study, a new ZJ7 isolate have been isolated from CV diseased dogs in Jilin province, a recent representative of canine distemper virus (CDV) in China northeast, and the identification of the isolate have been confirmed by virulence investigation and molecular analysis. 100% identities of nucleotide and amino acid sequences of H and P genes have been determined between the ZJ7 strain isolated in MDCK cell and the original virus from infected fresh tissues
The results indicated that the CDV was genetically stable after isolation within a few passages and the MDCK cell was a suitable cell line to isolate CDV from fresh tissues

Summary

Introduction

Canine distemper (CD) is an acute or subacute, highly contagious disease with signs of generalized infection including respiratory disease, foot pad hyperkeratosis, central nervous system disturbance or a combination of these symptoms [1]. Its causative agent is a canine distemper virus (CDV) that is an enveloped virus particle with a diameter of 150 to 300 nm [2], belonging to the Morbillivirus of Paramyxoviridae family. CDV is a single-stranded negative-sense RNA virus (~15.7-kb RNA genome) and causes a highly infectious, systemic and fatal disease in the wild and domestic Canidae [3,4]. An acute infection by CDV is associated with respiratory or gastrointestinal tract disease or both, and dpi without necrosis [5]. The lymph node follicles of dogs that naturally infected with CDV have pathological findings from necrosis to lymphoid depletion [12]

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Discussion

Conclusion