New genetic lineage of Ebola virus discovered in ...( This release is available in a hre...),Health

This release is available in French.

The Zaire species of Ebolavirus (ZEBOV) remains the most virulent of the various known species. It alone is responsible for 88% of human deaths from haemorrhagic fever recorded since Ebolas discovery in 1976. It was moreover the species involved in the two-month long epidemic which raged in the Democratic Republic of Congo (DRC) .In spite of the mass of scientific data collected during previous epidemics, the international scientific community has still not succeeded in determining the evolutionary development of the Ebolavirus and more particularly that of ZEBOV. Investigations were restricted by the scarcity of available data. Only 12 gene sequences coding for the glycoprotein (GP), a molecular structure that enables the virus to penetrate a cell before infecting it, have currently been identified. Furthermore, these sequences, isolated from infected humans between 1976 and 2001, appear to belong to a single genetic lineage originating from the first epidemic documented in the DRC in 1976. This apparent genetic uniformity therefore suggested that epidemics that broke out after 1976 all stemmed from the very first one. However, recent discoveries by a joint IRD-CIRMF team have called this hypothesis into question.

Between 2001 and 2006, these scientists discovered 47 animal carcasses in Gabon and the Republic of Congo. Among them were the remains of 18 gorillas and 5 chimpanzees. The rapid tissue decomposition of the carcasses meant that the search for RNA sequences coding for GP was conclusive for only 6 gorillas and one chimpanzee. Nevertheless, phylogenetic analysis of these was able to show that the virus which had contaminated the seven primates belonged to a new genetic lineage of ZEBOV. This lineage, named B, showed 2 to 3% genetic divergence from lineage A, the one in which scientists had hitherto classified all the virus
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