Genomic surveillance elucidates Ebola virus origin and transmission during the 2014 outbreak

TLDR

Ebola virus disease spread through Guinea, Liberia, Sierra Leone, and Nigeria during its largest outbreak. The study aims to monitor mutations that alter protein sequences and other biologically meaningful targets for their impact on diagnostics, vaccines, and therapies critical to outbreak response. The authors sequenced 99 Ebola virus genomes from 78 Sierra Leone patients at ~2000× coverage. Rapid interhost and intrahost genetic variation revealed that the West African variant diverged from central African lineages around 2004, crossed from Guinea to Sierra Leone in May 2014, and has maintained sustained human‑to‑human transmission without additional zoonotic sources.

Abstract

In its largest outbreak, Ebola virus disease is spreading through Guinea, Liberia, Sierra Leone, and Nigeria. We sequenced 99 Ebola virus genomes from 78 patients in Sierra Leone to ~2000× coverage. We observed a rapid accumulation of interhost and intrahost genetic variation, allowing us to characterize patterns of viral transmission over the initial weeks of the epidemic. This West African variant likely diverged from central African lineages around 2004, crossed from Guinea to Sierra Leone in May 2014, and has exhibited sustained human-to-human transmission subsequently, with no evidence of additional zoonotic sources. Because many of the mutations alter protein sequences and other biologically meaningful targets, they should be monitored for impact on diagnostics, vaccines, and therapies critical to outbreak response.