A research group from Nigeria found evidence of long-distance transmission and spread between bats corona virus isolated in Africa and Europe and Asia, as described in a new paper available on preprinted servers bioRxiv*.
The pandemic coronavirus 2019 (COVID-19), caused by acute acute coronavirus 2 (SARS-CoV-2) acute respiratory syndrome, is the current decisive global public health crisis. This virus belongs to a large group of coronaviruses, which are known to have zoonotic potential to spread from animals to humans.
Novel Coronavirus SARS-CoV-2 This scanning electron microscope image shows SARS-CoV-2 (yellow) – also known as 2019-nCoV, the virus that causes COVID-19 – isolated from a patient in the US, emerging from the cell surface (pink ) cultured in the lab. Images were taken and colored at NIAID’s Rocky Mountain Laboratories (RML) in Hamilton, Montana. Credit: NIAID
The rich fauna and biodiversity in Africa create hotspots for emerging viral diseases. Additional opportunities for viruses are various bats that can function as reservoirs, and which can efficiently spread pathogens (for example, African fruit bats are known to reach thousands of miles during their migration cycle).
Evidence shows African bats as a potential reservoir for some betacoronaviruses that can cause serious outbreaks. Some studies also suggest that SARS-CoV-2 might be extended to the human population by zoonotic events involving SARS-related betacoronavirus.
As a result, a research group from PT Federal Medical Center in Abeokuta, Agreement University at Otta, and Ibadan University in Nigeria decided to assess the phylogenetic diversity and dynamics of the evolution of African betacoronavirus among bats, and their possible spread across continents.
Analyzing evolution trees
Three data sets were generated from the Pathogen Virus resource database for the purpose of this study. More specifically, the authors obtained a partial RNA-dependent RNA polymerase (RdRP) gene sequence from bat coronaviruses from seven African countries, four European and three Asian countries.
Information such as host species, country of origin, and date of collection are combined with sequence data to make accurate phylogenetic determination. Cluster analysis is carried out with special software to identify sequence similarities and reduce data duplication.
Phylogenetic trees were concluded using MEGA software for manual and automatic sequence alignment, distribution analysis (both geographically and evolutionally) carried out using the Monte Carlo Markov Chain implemented in BEAST (platform for Bayesian phylogenetic molecular sequence analysis) and visualized with the SpreaD3 platform interactive.
Viruses that leap over continents
The most common bat species sampled in this study is the Peters dwarf dwarf batMicropteropus pusillus). At the same time, Cameroon is the country with the highest distribution of sample bat species in this study. However, recognized data gaps must be taken into account when assessing study findings.
Peter’s Dwarf Epauletted Fruit Bat (Micropteropus pusillus). Image Credit: Dave Montreuil / Shutterstock
“These results do not always represent a true picture of the diversity of bat species in Africa, because some countries do not have sequence information for bats due to lack of supervision,” the study authors caution.
In fact, so far, only a handful of studies have been carried out in Africa on the corona virus among bats, which has left a considerable gap in epidemiological information about beta bat coronavirus in Africa.
This study adds additional knowledge about the phylogeny of the beta coronavirus sequence, which revealed that most African strains included in the D derivative – consisted of strains from Cameroon, Democratic Republic of Congo, Kenya, Madagascar, and Nigeria. This corroborates previous reports that identified a clade circulating throughout the African continent.
In addition, the researchers hinted at inter-species transmission among the lineage betacorona D virus, which allows for the potential recombination and rapid evolution of this lineage. Also, the circulation of two different B and C lineages between African bat species is indicated.
Finally, the phylogenic spread of bat coronaviruses reveals a large number of inter-continental and intra-continental spread events. The first shows the spread of the virus from China and Hong Kong to Central and South Africa, while the second shows the spread between Cameroun, the Democratic Republic of Congo and South Africa, and directly from Cameroon to Madagascar.
Study the shortcomings and conclusions
Although this insight is very important for further tracking of the corona virus, one major limitation of research is the inability to analyze the protein sequence data for these spike viruses. Such an approach will provide more relevant data about their evolution regarding transmission and infectivity.
In addition, the population demographics reported in this study may not realistically describe virus populations because the size of the dataset used is limited and may not represent the true demographic population of the bat corona virus in Africa.
“However, we have demonstrated the importance of molecular surveillance of zoonotic potentials such as coronaviruses,” the study authors said. “We advocate for broader cross-continent research involving the full genome sequences of betacoronavirus to better understand the causes of their emergence and the spread of zoonoses into human populations,” they concluded.
However, we must be aware that coronavirus-related SARS bats will continue to spread to human populations. Other possible deadly pandemics are rare; However, that opportunity increases with the frequency of the spillover. Thus the scientific community must remain vigilant.
* Important Notification
bioRxiv publishing initial scientific reports that are not reviewed by colleagues and, therefore, should not be considered conclusive, guide clinical practice / health-related behaviors, or be treated as pre-existing information.