Genetic characterization of an isolate of canine distemper virus from a Tibetan Mastiff in China

Abstract

Canine distemper (CD) is a highly contagious, often fatal, multisystemic, and incurable disease in dogs and other carnivores, which is caused by canine distemper virus (CDV). Although vaccines have been used as the principal means of controlling the disease, CD has been reported in vaccinated animals. The hemoagglutinin (H) protein is one of the most important antigens for inducing protective immunity against CD, and antigenic variation of recent CDV strains may explain vaccination failure. In this study, a new CDV isolate (TM-CC) was obtained from a Tibetan Mastiff that died of distemper, and its genome was characterized. Phylogenetic analysis of the H gene revealed that the CDV-TM-CC strain is unique among 20 other CDV strains and can be classified into the Asia-1 group with the Chinese strains, Hebei and HLJ1-06, and the Japanese strain, CYN07-hV. The H gene of CDV-TM-CC shows low identity (90.4 % nt and 88.9 % aa) with the H gene of the classical Onderstepoort vaccine strain, which may explain the inability of the Tibetan Mastiff to mount a protective immune response. We also performed a comprehensive phylogenetic analysis of the N, P, and F protein sequences, as well as potential N-glycosylation sites and cysteine residues. This analysis shows that an N-glycosylation site at aa 108-110 within the F protein of CDV-TM-CC is specific for the wild-type strains (5804P, A75/17, and 164071) and the Asia-1 group strains, and may be another important factor for the poor immune response. These results provide important information for the design of CD vaccines in the China region and elsewhere.

Isolation and phylogenetic characterization of Canine distemper virus from India

“…The present study clearly shows the distinct genetic relationships of Indian wild-type virus from vaccine strains and other known lineages of CDV around the world. H gene of a new CDV isolate TM-CC showed low identity (90.4 % nt and 88.9 % aa) with the H gene of the classical Onderstepoort vaccine strain and this could be one of the reason for host's inability to mount a protective immune response against CDV [14]. The observed diversity between the vaccine strains and the wild-type CDVs may be due to antigenic escape, genetic recombination between wild-type strains, adaptation to new host species that drive the evolution of the virus [8].…”

“…In F protein, maximum sequence variation was found in the signal peptide region (1-135 aa). Signal peptide region of F protein has the lowest amino acid homology and is reported to be geographically distinct [14].…”

“…N-linked glycosylation in case of viruses has a potential role in its virulence and immune interaction properties [27]. N-linked glycosylation site at aa positions 309-311 in H protein, is reported to be specific for virulent strains of CDV with the exception of (AF164967) Switzerland [4,10,14]. This glycosylation site was also missing in Indian strain.…”

“…Although vaccines have been widely used in most of the countries for controlling the disease yet CD still has been reported in some vaccinated animals. The hemagglutinin (H) protein is one of the most important antigens for inducing protective immunity against CD, and any variation of recent CDV strains may result in vaccination failure [14].…”

Detection of Local Isolates of Canine Distemper Virus by Reverse-Transcription Polymerase Chain Reaction

“…It has been reported that genomic differences occur between the wild-type CDV and the vaccine strains (Li et al, 2014). H gene is considered to be highly mutagenic (Martella et al, 2006).…”