Mechanisms of Ebola virus replication and transmission in Angolan free-tailed bats

Ebola virus (formerly known as Zaire ebolavirus) is known to be one of the deadliest human pathogens on our planet for more than 40 years, however, there is still no convincing evidence identifying a natural reservoir host nor the mechanisms of virus circulation in nature. Now, an international team lead by scientists from Robert Koch Institute have shown experimentally how Ebola virus replicates and transmits in Angolan free-tailed bats which are common in Sub-Saharan Africa. Their findings have been published in Nature Communications (“Selective replication and vertical transmission of Ebola virus in experimentally infected Angolan free-tailed bats”, Nature Communications 2024).

Although Angolan free-tailed bats (Mops condylurus) are regarded a suspected reservoir host for Ebola virus, questions of virus replication and transmission in these animals have not been answered to-date as research with bats is highly challenging. In order to fill this gap, the researchers built a bat husbandry in West Africa to capture, keep and train the animals on-site. Then, the researchers transported them to the Robert Koch Institute’s BSL-4 laboratory in Berlin where they finally established an infection model for Ebola virus and investigated the permissiveness of Angolan free-tailed bats to various filoviruses such as Ebola virus, Marburg virus, Taï Forest virus and Reston virus.

The team found that first, only bats inoculated with Ebola virus show high and disseminated viral replication and infectious virus shedding, without clinical disease – showing plausible routes of infection and virus circulation. The other filoviruses tested failed to establish such infections. Second, Ebola virus is able to traverse the bats’ placenta, infect and persist in foetal tissues – a so far unknown transmission route that might be required for the maintenance of Ebola virus in small reservoir populations. Third, Ebola virus demonstrate a high genetic stability and therefore slow evolution when shifting hosts, indicating a readily virus replication in humans after spillover from a natural host without requiring genetic adaptation. It is important to note that the findings shed light on plausible routes of infection and virus circulation in Angolan free-tailed bats in an experimental setting, but they do not prove that these animals are the host for Ebola virus in Africa. For this, further data and epidemiological studies are needed.

Photos and videos of RKI’s bat research are available at www.rki.de/zbs5-rg1-en.

Videos of working in a BSL-4 laboratory are available at www.rki.de/bsl4-en; press photos of the BSL-4 are available at www.rki.de/press.

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