Viruses in bats and potential spillover to animals and humans

Abstract

In the last two decades, several high impact zoonotic disease outbreaks have been linked to bat-borne viruses. These include SARS coronavirus, Hendra virus and Nipah virus. In addition, it has been suspected that ebolaviruses and MERS coronavirus are also linked to bats. It is being increasingly accepted that bats are potential reservoirs of a large number of known and unknown viruses, many of which could spillover into animal and human populations. However, our knowledge into basic bat biology and immunology is very limited and we have little understanding of major factors contributing to the risk of bat virus spillover events. Here we provide a brief review of the latest findings in bat viruses and their potential risk of cross-species transmission.

Figure 1

Phylogeny of coronaviruses. The phylogenetic analysis is done using Maximum Likelihood method with the General Time Reversible model in MEGA7. The percentage of trees in which the associated taxa clustered together is shown next to the branches. The tree is drawn to scale, with branch lengths measured in the number of substitutions per site. The analysis was conducted with 24 representative genome sequences with corresponding GenBank numbers provided in the tree. The three CoVs with proven lethal disease outbreaks are highlighted in red. Genus names are provided on the right with bars indicating the taxonomy boundaries.

Figure 2

Different routes of transmission of known henipaviruses in various outbreaks. During henipavirus outbreaks, transmission of the virus may be via an amplifying host (such as horse for HeV and pigs for NiV), or the virus may be transmitted directly from bats to humans via contamination in food, drink or environment.

Figure 3

Genetic relationship of all known filoviruses. The phylogenetic tree was built using MEGA7 using the Neighbor-Joining method with p-distance model under pairwise deletion. The bootstrap value is 1000. Virus abbreviation, full name and accession number are as follows: TAFV, Taï forest virus, NC_014372; BDBV, Bundibugyo virus, NC_014373; EBOV, Ebola virus, NC_002549; SUDV, Sudan virus, NC_006432; RESTV, Reston virus, NC_004161; BOMV, Bombali virus, MF319186; LLOV, Lloviu virus, NC_016144; MARV, Marburg virus, NC_001608; RAVV, Ravn virus, NC_024781; MLAV, Měnglà virus, KX371887; XILV, Xīlǎng virus, MG599980; HUJV, Huángjiāo virus, MG599981. The two newest members (BOMV and MLAV) are highlighted in red. Genus names are provided on the right with bars indicating the taxonomy boundaries.