Molecular insights from 2023 and 2024 outbreaks reveal exclusive circulation of peste des petits ruminants virus lineage IV in India.

Peste des petits ruminants (PPR) is a highly contagious disease affecting sheep and goats, caused by PPR virus (PPRV), a member of the genus Morbillivirus. In 2023 and 2024, on testing of suspected clinical samples for PPR received through passive surveillance of sheep and goat flocks in various states of India resulted in the documentation of 15 laboratory-confirmed outbreaks of PPR. During the outbreak investigation, morbidity and significant mortality rates were observed, and clinical samples collected from the affected flocks were tested using ELISA and RT-PCR, confirming the presence of PPRV. We studied in detail nine out of 15 confirmed outbreaks for characterization of virus including partial sequencing of nucleocapsid (N) and fusion (F) genes of the PPRV. In addition, the virus from each outbreak was isolated from tissue and swab samples by blind passage in Vero cells. Phylogenetic analysis based on partial N gene sequences revealed that all of the Indian isolates belonged to Asian lineage IV. This study confirms that all of the cases of PPR reported so far in India have been caused by PPRV lineage IV.