Clinicopathological and molecular characterization of Morbillivirus caprinae Lineage IV in PPR outbreak among small ruminants of Punjab.

Peste des petits ruminants (PPR) is a highly contagious viral disease affecting sheep and goats, posing a significant threat to small ruminant health and rural livelihoods in Punjab, India. The objective of the present study was to investigate cases of per-acute mortality caused by Morbillivirus caprinae, which resulted in the death of 24.86 % (134/539) of animals across ten different sheep and goat farms. The overall morbidity, mortality and case fatality rate were observed during the outbreak investigation. However, necropsy and histopathological findings were strongly indicative of Morbillivirus caprinae infection in domestic small ruminants. The presence of PPRV was confirmed through Sandwich ELISA and one-step RT-PCR assays. The study also investigated potential interspecies transmission between goats and sheep in mixed flocks during a recent PPR outbreak. Genetic analysis of samples from affected flocks in neighboring regions revealed close similarity with other Asian PPRV isolates, indicating possible regional viral circulation. Phylogenetic analysis based on the nucleocapsid (N) protein gene revealed that the virus belonged to Lineage IV and was detected in samples from infected sheep, domestic goats, and animals from mixed farms. These findings suggest the likely spread of Lineage IV PPRV strains within the small ruminant population in the region, potentially originating from domestic goats.