Bombali ebolavirus has been detected among bats in Mozambique

By Pooja Toshniwal PahariaNov 18 2022Reviewed by Aimee Molineux

In a recent study published in Emerging Infectious Diseases, researchers reported on the detection of Bombali virus (BOMV, of the ebolavirus genus) ribonucleic acid (RNA) among three free-tailed Mops condylurus (Molossidae) bat species in Mozambique.

Background

Studies have reported six viral organisms of the Ebolavirus genus, including Sudan, Zaire, Bundibugyo, Bombali, Taï Forest, and Reston), a few of which have caused disease outbreaks with considerable mortality in the African continent.

BOMV was initially detected among free-tailed bat species of the Molossidae family, particularly in the Chaerephon pumilus and Mops condylurus bat species in the year 2016 in Sierre Leone’s Bombali district.

Two years later, BOMV was identified in Mops condylurus bat species in Kenya and a year later, in Guinea. Studies have not reported BOMV-induced infections in humans, including individuals who experience symptoms of febrile diseases and reside in locations where the Bombali virus has been detected among bats. BOMV is the only ebolavirus identified recurrently by polymerase chain reaction (PCR) between 2015 and 2019 and among bats located more than 5,000 kilometers apart.

BOMV epidemiology in Mops condylurus bats is not completely known. Seasonal alterations in population-based and environmental changes are key drivers of the dynamics of infectious agent transmission in nature-based settings. For example, pulses of paramyxovirus, coronavirus, and Marburg virus shedding have coincided with a seasonal rise in juveniles among bats.

About the study

In the present study, researchers detected Bombali virus RNA among three female Mops condylurus bats caught in Mozambique at a site located towards the southeast of the geographical range of the bats.

In May 2015, samples were obtained from 54 Mops condylurus bat species living in buildings in southeastern Mozambique’s Inhassoro district and other bats (n=211 of 10 other bat species), residing mostly in caves. All samples were screened for viruses that belonged to the Coronaviridae, Paramyxoviridae, and Astroviridae families. RNA was extracted from the samples and subjected to reverse transcription PCR (RT-PCR) analysis.

Complementary deoxyribonucleic acid (DNA) was screened using three assays that target the large protein (L) gene of the Filoviriridae family, and the products of PCR analysis were sequenced. Maps were generated with data obtained from the International Union for Conservation of Nature Red List website and Natural Earth. The phylogenetic analysis was performed based on the transversion plus gamma evolutionary modeling. A maximum likelihood tree was generated based on partial nucleotide sequences (587 base pairs) of the L gene of certain filoviruses.

Results

The study findings underpinned Bombali virus detection towards the south of the geographical range of Mops condylurus bats, a known residential location of the bat species. Partial L gene sequencing showed that the genomic sequences of BOMV identified in Mozambique bats were closely associated with sequences documented among bats from Kenya, Guinea, and Sierra Leone.

The virus was detected in three bats in Guinea between May 2018 and March 2019. In Sierra Leone, the virus was identified in one adult female in May 2016. In Kenya, the virus was detected in one adult female in May 2018 and two adult females in May 2019. In Mozambique, the virus was detected in three females in May 2014.

Even though the results were obtained based on short genomic sequences (587 base pairs), they indicated a strong relationship between M. condylurus and BOMV bats throughout their geographical range. BOMV was detected only in bats of the female sex, with no differences between adult and subadult populations. The team captured most BOMV-positive bats in day-roost regions occupied by livestock or humans.

Conclusions

Overall, the study findings supported the suspicion that Mops condylurus bats play a role in maintaining BOMV. Neither the Bombali virus nor any other ebolavirus species had been identified in human beings In Mozambique, highlighting that the study findings must not be regarded as proof of a massive warning to local community-swelling individuals. Still, they should instead catalyze the initiation of future studies and continue surveillance efforts.

Further research must emphasize other members of the Molossidae family of bats since the Bombali virus was first documented in Chaerephon pumilus, a part of the bat family that frequently roosts in synanthropic sites and thus gives rise to spillover opportunities. Using a unified One Health method (i.e., multisectoral, transdisciplinary, and collaborative) may prevent disease outbreaks in the future, promote sustainable human community development, and protect bats with major functional roles in several ecosystems.