Survey of Ebola Viruses in Frugivorous and Insectivorous Bats in Guinea, Cameroon, and the Democratic Republic of the Congo, 2015–2017

Abstract

To clarify the role of bats in the ecology of Ebola viruses, we assessed the prevalence of Ebola virus antibodies in a large-scale sample of bats collected during 2015–2017 from countries in Africa that have had previous Ebola outbreaks (Guinea, the Democratic Republic of the Congo) or are at high risk for outbreaks (Cameroon). We analyzed 4,022 blood samples of bats from >12 frugivorous and 27 insectivorous species; 2–37 (0.05%–0.92%) bats were seropositive for Zaire and 0–30 (0%–0.75%) bats for Sudan Ebola viruses. We observed Ebola virus antibodies in 1 insectivorous bat genus and 6 frugivorous bat species. Certain bat species widespread across Africa had serologic evidence of Zaire and Sudan Ebola viruses. No viral RNA was detected in the subset of samples tested (n = 665). Ongoing surveillance of bats and other potential animal reservoirs are required to predict and prepare for future outbreaks.

Comparative analysis of serologic cross-reactivity using convalescent sera from filovirus-experimentally infected fruit bats

“…Using filovirus-specific antisera collected from bats that were prime-boosted at the same time not only allowed us to thoroughly examine the level of serological cross-reactivity between the virus-specific antisera and heterologous filovirus antigen, but also provided the opportunity to use this knowledge to evaluate previously published ebolavirus serosurveys of bats [22][23][24][25][26][27][28][29][30][31][32] . Four out of the 11 previously published ebolavirus serosurveys of bats used Ebola virus antigen only to detect ebolavirus IgG antibodies 22,[24][25][26] and another four of these serosurveys used Ebola and Reston antigens only to detect ebolavirus IgG antibodies 23,[27][28][29] .…”

“…Yet, infectious virus was not isolated from any of these species 22,23 , indicating that they are either dead-end virus hosts, had cleared virus infection prior to sampling, or that current filovirus isolation techniques lack the sensitivity to recover infectious virus from specimens with low viral loads. Serological reactivity of bat sera with ebolavirus antigens using indirect ELISAs, indirect fluorescent tests, bead-based multiplex assays and/or western blots has been reported in 375 bats representing at least 21 species throughout sub-Saharan Africa and Asia [22][23][24][25][26][27][28][29][30][31][32] . However, interpretation of this data has been exceedingly difficult due to multiple reasons that include: (1) the absence of a panel of positive and negative bat sera for initial serological assay validation and continuing quality control, (2) the use of various uncharacterized recombinant filovirus antigens, and (3) the application of different statistical methods for establishing cutoff values for seropositivity.…”

Serological evidence of exposure to ebolaviruses in domestic pigs from Guinea

“…However, our understanding of the virus ecology including virus transmission and maintenance in nature is still limited. Although virus isolates from bats are still lacking, molecular and serological evidence points towards these animals as the most likely natural virus reservoir (De Nys et al, ; Goldstein et al, ; Leroy et al, ; Ogawa et al, ; Pourrut et al, ). The recent discovery of a full‐length ebolavirus genome, designated Bombali virus (BOMV), in insectivorous bats from Sierra Leone (Goldstein et al, ) and the finding of partial BOMV nucleotide sequences in bats from Kenya (Forbes et al, ) and Guinea (Karan et al, ) underline the complexity of ebolavirus ecology and the potential role of bats in it.…”

The Emerging Threat of Ebola

“…Antibodies are formed when an organism has been exposed to an infectious organism. This is evidence of exposure and immune response, but not of long-term infection or viral shedding [33]. Only one small study has ever isolated Ebola RNA from bats [72].…”