Isolation and genetic characterization of canine distemper virus in domestic dogs from central and northern provinces in Vietnam

Phylogenetic and sequence analysis of the co-circulating lineages in the canine distemper virus complexity from Northern Vietnam (2017-2023)

Morbillivirus canis, commonly known as Canine distemper virus (CDV), causes Canine distemper (CD) in carnivore species across the world and spreads via cross-species transmission between domestic and wildlife canids, non-canid carnivores, and omnivores. We report on the Asia-4 lineage of CDV previously documented in Thailand and China, which has emerged for the first time in northern Vietnam since 2017. The phylogenetic analysis of 121 complete nucleotide CDS (coding sequence) of the hemagglutinin (H) gene, including 20 from this study, and 101 reference strains from all 19 lineages of CDVs revealed that the Asia-4 lineage co-circulated with the Asia-1 in Vietnam. The evolutionary distances (ED) or genetic distances between the Vietnamese and typical Asia-4 strains was low, substantially distinguishing them from other lineages. The immunodominant epitopes, host-switching, and glycosylation sites in Asia-4 viruses have several site alterations, providing fair insights into the effectiveness of the America-1-based vaccine. In addition to Thailand, China, Russia, and Mongolia, the Asia-4 lineage has appeared in northern Vietnam. Whether via canine and pet or wild animal trade/border crossing trafficking to Vietnam, remains to be studied. Our findings contribute to a better understanding of CDV molecular epidemiology and the suitable application of lineage-antigenic matching vaccines, as well as the complicated co-circulation of multiple-lineage strains in Vietnam.

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

Canine distemper virus (CDV) is a highly contagious virus that affects domestic and wild animals, causing severe illness with high mortality rates. Rapid monitoring and sequencing can provide valuable information about circulating CDV strains, which may foster effective vaccination strategies and the successful integration of these into conservation programs. During two site visits in Bangladesh in 2023, we tested a mobile, deployable genomic surveillance setup to explore the genetic diversity and phylogenetic patterns of locally circulating CDV strains. We collected and analysed 355 oral swab samples from stray dogs in Rajshahi and Chattogram cities, Bangladesh. CDV-specific real-time RT-PCR was performed to screen the samples. Out of the 355 samples, 7.4% (10/135) from Rajshahi city and 0.9% (2/220) from Chattogram city tested positive for CDV. We applied a real-time RT-PCR assay and a pan-genotype CDV-specific amplicon-based Nanopore sequencing technology to obtain the near-completes. Five near-complete genome sequences were generated, with phylogenetic relation to the India-1/Asia-5 lineage previously identified in India. This is the first study to provide genomic data on CDV in Bangladesh and the first demonstration of a mobile laboratory setup as a powerful tool in rapid genomic surveillance and risk assessment for CDV in low resource regions.