Courcelles, M.; Tounkara, K.; Mantip, S.; Niang, M.; Kounta Sidibe, C. A.; Sery, A.; Dakouo, M.; Luka, P. D.; Adedeji, A.; Shamaki, D.; Muhammad, M.; Ali, Y. H.; Saeed, I. K.; Awuni, J.; Odoom, T.; Tetteh, P. A.; Yingar, D. T.; Wade, A.; Dickmu, S.; Diddi, A.; Shawash, H.; Couacy-Hymann, E.; Mathurin, K. Y.; Ouled Ahmed Ben Ali, H.; Ben Hassen, S.; hadouchi, s.; Alm-ajali, A.; Settypalli, T. B. K.; Lamien, C. E.; Salami, H.; Rassoul, S.; Asnaoui, M.; Cetre-Sossah, C.; Guendouz, S.; Kwiatek, O.; Libeau, G.; Dundon, W. G.; Bataille, A.

Peste des petits ruminants (PPR) is a highly contagious viral disease of small ruminants caused by the peste des petits ruminants virus (PPRV), which is classified into four distinct genetic lineages (I-IV). A critical concern in the recent epidemiological history of PPRV is the rapid and widespread expansion of lineage IV (LIV) across West Africa over the past decade. This dominance suggests a potential adaptive advantage of circulating LIV strains in the regions current epidemiological context. In this study, we obtain the genome sequence of 26 new PPRV samples, including historical (pre-2000) and many recent African LIV isolates, offering the first opportunity to investigate the evolutionary history of LIV in Africa and identify genetic events potentially associated with its recent spread. Phylogenomic analyses implemented on a dataset of 167 curated PPRV genome sequences reveal that the most ancestral LIV group comprises strains circulating in Sub-Saharan Africa (designated clade LIVssa), providing robust evidence for an African origin of lineage IV. Our results further indicate that PPRV strains linked to the recent West African expansion of LIV belong to a specific LIVssa subgroup, termed NigB. We identified multiple signatures of selection pressure within the LIVssa sublineage, particularly in the NigB cluster. Several amino acid substitutions unique to LIVssa or NigB were detected, some of which may impact protein function and warrant prioritised investigation. Additional genomic data are required to confirm the association between the NigB group and the ongoing spread of LIV in West Africa. The evolutionary adaptations observed in LIVssa - potentially enhancing transmission efficiency, host range or pathogenicity - could undermine current disease control strategies in regions where PPR poses significant threats to food security and local economies.