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Regional evolutionary dynamics of Peste des petits ruminants virus in West Africa: influence of livestock trade. [O24]

Bataille A., Coste C., Salami H., Lo M., Seck I., Diop M., Bezeid O.E.M., El Arbi A.S., Kaba L., Niang M., Kwiatek O., Lancelot R., Libeau G.. 2016. In : Programme and abstracts EPIZONE Going Viral. Madrid : EPIZONE, p. 56-56. Annual Meeting EPIZONE Going Viral. 10, 2016-09-27/2016-09-29, Madrid (Espagne).

Peste des petits ruminants (PPR) is a highly contagious and devastating viral disease of small ruminants. It represents a serious risk for the economy and food security in regions of Africa, Middle East and Asia where the disease is endemic. Integrated knowledge of evolutionary and epidemiological factors underlying PPR virus (PPRV) emergence, persistence and spread are necessary for better guidance of PPR control strategies and their practical implementation. Efforts are especially needed to better understand the regional dynamics of PPRV evolution and endemic transmission. Here we studied the regional evolutionary dynamics of endemic PPRV in West Africa, focussing on Senegal and neighbouring countries, and assessed the role of livestock trade in explaining the observed viral diversity and phylogenetic patterns. Sheep and goats were sampled in livestock markets and villages across Senegal between 2010 and 2014 and tested for PPRV infection. Other samples were obtained from Mauritania, Mali, and Guinea during the same period. Historical samples (1972-1994) were also collected from the region. In addition, livestock movement data, particularly livestock trade were collected during specific surveys implemented in Mauritania and Senegal. A total of 55 samples collected from 2010 to 2014 were positive for PPRV. Partial sequencing of the N gene showed that 54 belonged to the PPR virus lineage II (PPRV-II) and one to lineage I. We obtained the sequence of the full N and H genes for all PPRV-II samples, and sequenced the full genome for a subset of recent and historical samples. Phylogenetic analyses showed the presence of at least 4 different, geographically delimited, clades within PPRV-II in West Africa. Samples from Mali were distributed across 3 of these clades, suggesting a central position of the country in regional movement of PPR. All PPRV-II samples from Senegal were situated within a single clade, but could be separated in distinct clusters. These clusters pointed to virus movement across long distances within Senegal and between Senegal and its neighbours. Transboundary movements involved mainly major sites for commercial animal movement, but also transhumant movement between Senegal and Mauritania. A statistical model of virus genetic distance was fitted with environment and animal movement data to assess if the genetic patterns observed can be predicted by commercial connectivity. We discuss how such landscape resistance analyses based on animal movement can be used to predict PPR transmission pathways and control effort within endemic regions. (Texte intégral)

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