The genetic impact of an Ebola outbreak on a wild gorilla population

Claudia Fontsere,Nelly Ménard,Christina Hvilsom,Jessica Hernandez-Rodriguez,David Hughes,Pascaline Le Gouar,Peter Frandsen,Tomas Marques-Bonet,Dominique Vallet,Camilla Hjorth Scharff-Olsen,Arcadi Navarro,Hans R Siegismund,Jonas Niemann,M Thomas P Gilbert,Martin Kuhlwilm

doi:10.1186/s12864-021-08025-y

Abstract

BackgroundNumerous Ebola virus outbreaks have occurred in Equatorial Africa over the past decades. Besides human fatalities, gorillas and chimpanzees have also succumbed to the fatal virus. The 2004 outbreak at the Odzala-Kokoua National Park (Republic of Congo) alone caused a severe decline in the resident western lowland gorilla (Gorilla gorilla gorilla) population, with a 95% mortality rate. Here, we explore the immediate genetic impact of the Ebola outbreak in the western lowland gorilla population.ResultsAssociations with survivorship were evaluated by utilizing DNA obtained from fecal samples from 16 gorilla individuals declared missing after the outbreak (non-survivors) and 15 individuals observed before and after the epidemic (survivors). We used a target enrichment approach to capture the sequences of 123 genes previously associated with immunology and Ebola virus resistance and additionally analyzed the gut microbiome which could influence the survival after an infection. Our results indicate no changes in the population genetic diversity before and after the Ebola outbreak, and no significant differences in microbial community composition between survivors and non-survivors. However, and despite the low power for an association analysis, we do detect six nominally significant missense mutations in four genes that might be candidate variants associated with an increased chance of survival.ConclusionThis study offers the first insight to the genetics of a wild great ape population before and after an Ebola outbreak using target capture experiments from fecal samples, and presents a list of candidate loci that may have facilitated their survival.

Highlights

Numerous Ebola virus outbreaks have occurred in Equatorial Africa over the past decades
A total of 31 non-invasive fecal samples from identified western lowland gorillas were collected between 2001 and 2014 in Odzala-Kokoua National Park, Congo [18] (Fig. 1A). Sixteen of these were from individuals declared missing after the Zaire Ebola virus outbreak in 2004
No immunological test could be performed on the dried fecal samples, the survivors were known to live in the area where the epidemic emerged and they were suspected to have been in contact with the virus

Summary

Introduction

Numerous Ebola virus outbreaks have occurred in Equatorial Africa over the past decades. The 2004 outbreak at the OdzalaKokoua National Park (Republic of Congo) alone caused a severe decline in the resident western lowland gorilla (Gorilla gorilla gorilla) population, with a 95% mortality rate. The Ebola virus (EBOV), discovered in 1976, causes a severe disease and often fatal hemorrhagic fever for which numerous human outbreaks have been reported throughout Africa [1]. Fontsere et al BMC Genomics (2021) 22:735 that occurred in Ituri, North Kivu and South Kivu provinces of Democratic Republic of Congo was declared over by the World Health Organization (WHO), 3470 cases had been reported with 2287 deaths (fatality rate of 66%) [3]. Ebola hemorrhagic fever or Ebola virus disease (EVD) is an acute and severe disease with a fatality rate in humans around 50% [5,6,7]

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Conclusion