Molecular characterisation and histopathological analysis of canine distemper virus in a Malayan tiger (Panthera tigris jacksoni)

Background Canine distemper virus (CDV) has a broad host range, spanning carnivorous and non-carnivorous animals, often proving fatal. The detection of CDV in a Malayan tiger in Malaysia in 2019 marks the first such case in Malayan tigers, highlighting the potential domestic animal or wildlife circulation of the virus. Our study aimed to describe histological manifestations and characterise the CDV strain in the tiger to determine its molecular epidemiology and postulate viral pathogenicity. Results Notable histopathological changes were observed primarily in the central nervous system, lung, liver, kidney, spleen, and stomach, with viral antigens localised in the lung, liver, kidney, and stomach tissues. CDV-induced cell cytopathic effects with viral quantification yielding 4.27 x 10 ⁶ TCID ₅₀ /mL were observed at 48 h post-inoculation in CHO-SLAM cells. Phylogenetic analysis suggested that the virus originated from the Asia-1 region. Notably, 549H and 519I mutation combinations in the hemagglutinin protein were observed, indicating adaptation to a non-canid wildlife species. Conclusion This study delved into the molecular characterisation of CDV in the Malayan tiger, with information on the dynamics of virus transmission among wildlife in the case of future outbreaks. Such results underscore the need for a prevalence study to assess the spread of the virus. This can serve as a benchmark for developing effective preventative measures to protect Malayan tigers and mitigate their risk of extinction.