Phylogenetic characterization of canine distemper virus from stray dogs in Kathmandu Valley

Abstract

Canine distemper is a highly contagious, often fatal disease caused by canine distemper virus (CDV) in domestic dogs and wild carnivores. The virus has caused mass epidemics in both wild and captive carnivores of high conservation value such as tigers, lions and leopards. Hence, understanding and managing CDV outbreaks is particularly important in Nepal, which is home to many species of threatened wild carnivores including tigers, leopards, snow leopards, dholes and wolves, and also contains a large population of stray dogs. Previous studies have suggested that CDV may pose a threat to wild carnivores, but there have not been any studies characterizing the genetic strains of the virus circulating in Nepal’s carnivores. We collected invasive and non-invasive biological samples from stray dogs in Kathmandu Valley and genetically characterized the strains of CDV in the dogs to belong to the Asia-5 lineage by using phylogenetic analysis. The same lineage also contained CDV strains sequenced from dogs, civets, red panda and lions in India. Based on our phylogenetic analysis, we think it is likely that CDV is maintained through sylvatic cycle among sympatric carnivores allowing the recurring spillovers and outbreaks. It is crucial to prevent the virus transmission from reservoir hosts to other species, especially threatened populations of large carnivores in Nepal. Hence, we recommend for regular surveillance of CDV targeting wild carnivores in addition to the domestic dogs.

Snapshot study of canine distemper virus in Bangladesh with on-site PCR detection and nanopore sequencing

“…Besides the hemagglutinin (H) gene classification, analysing the complete CDV genome provides a better understanding of viral genetics, possible interspecies transmission and especially for genomic recombination 7 . In Asia, several lineages of CDV have been classified so far, namely as Asia-1, Asia-2, Asia-3, Asia-4 and Asia-5 lineages 8 – 12 . Moreover, more recently novel lineages were identified based on amino acid sequence divergence level from known CDV lineages.…”

“…Adopting stray dogs, implementing sterilization programmes, and providing access to vaccinations are vital steps to curbing overpopulation and mitigating disease transmission 28 . Considering that, CDV has a higher rates of cross-species transmission potential and can cause outbreaks 29 , by reducing the incidence of CDV infections in domestic animals, vaccination and other prevention programmes indirectly contributes to controlling the transmission of the virus in both captive and wild animal populations 12 . From a conservation perspective, there are several wild and captive endangered animal species such as Bengal tiger ( Panthera tigris tigris ) and Indian leopard ( Panthera pardus fusca ) in Bangladesh that are at clear risk to CDV infection 30 .…”