Sequencing of the PPR virus caused outbreaks in Nubian ibex and mountain gazelles in Saudi Arabia from 2022-2024

Background Morbillivirus caprinae , or PPRV, is the causative agent of devastating illnesses in wild and domestic ruminants worldwide namely Peste des petites ruminants (PPR). It causes mouth erosion, pneumonia, enteritis and fatality in acute cases. Saudi Arabian authorities focus on wildlife conservation considering the Kingdom's biodiversity as their natural heritage. Milestones have been achieved in this context, protecting scarce populations from ibex, gazelles, oryx and many other endangered species. PPR is endemic in Saudi Arabia causing repeated outbreaks in domestic and wild ungulates despite vaccination, threatening conservation. In this study, recurrent PPR outbreaks were detected in semi captive settings in Saudi Arabia between 2022 and 2024. Where 309 samples from different wild ruminants were sent to Weqaa central laboratory in Riyadh. The sequencing of the circulating virus in Nubian ibex and mountain gazelles was performed to investigate these outbreaks. The samples were initially screened by real time RT‒PCR then full N, P and partial F and H genes were sequenced in Nubian ibex and mountain gazelle (n = 2). Results PPRV was detected in 72% of the samples collected. Phylogenetic analysis revealed that the virus classified in lineage IV closer to a Turkish strain (MN657232). Compared with the used 75/1 vaccine, the field virus showed substitutions in 18 amino acids in the N protein, 9 critical amino acids in the H protein and 7 amino acids in the F protein. These numerous substitutions at critical points affect H and F 3D structures and linear epitopes, suggesting that the virus may have escaped lineage II 75/1 vaccination either partially or completely. Conclusion The transboundary nature of PPRV and the potential role of wildlife in the spread of the virus in Saudi Arabia need to be considered. To the best of our knowledge, this report is the first to characterize PPRV genetically in wild ruminants in Saudi Arabia that needs further investigations on the protective immune response elicited in wild ruminants and atypical hosts after conventional PPR vaccination. Prober investigation of the effectivity of vaccination programs in wild and atypical hosts of PPR can could significantly influence the success of global eradication initiatives.