Alphavirus Identification in Neotropical Bats

Abstract

Alphaviruses (Togaviridae) are arthropod-borne viruses responsible for several emerging diseases, maintained in nature through transmission between hematophagous arthropod vectors and susceptible vertebrate hosts. Although bats harbor many species of viruses, their role as reservoir hosts in emergent zoonoses has been verified only in a few cases. With bats being the second most diverse order of mammals, their implication in arbovirus infections needs to be elucidated. Reports on arbovirus infections in bats are scarce, especially in South American indigenous species. In this work, we report the genomic detection and identification of two different alphaviruses in oral swabs from bats captured in Northern Uruguay. Phylogenetic analysis identified Río Negro virus (RNV) in two different species: Tadarida brasiliensis (n = 6) and Myotis spp. (n = 1) and eastern equine encephalitis virus (EEEV) in Myotis spp. (n = 2). Previous studies of our group identified RNV and EEEV in mosquitoes and horse serology, suggesting that they may be circulating in enzootic cycles in our country. Our findings reveal that bats can be infected by these arboviruses and that chiropterans could participate in the viral natural cycle as virus amplifiers or dead-end hosts. Further studies are warranted to elucidate the role of these mammals in the biological cycle of these alphaviruses in Uruguay.

Keywords: Chiroptera; Uruguay; alphavirus; arbovirus.

Figure 1

Geographical place of Uruguay in South America and its political division. Alphavirus seroprevalence in horses is depicted in color gradation by percentage ranks; mosquito-positive samples are depicted as ■ = EEEV and ▲ = RNV (data according to Burgueño et al., 2018). Places and number of bat sampling and alphavirus results are shown as ■ = EEEV and ▲ = RNV (this work).

Figure 2

Maximum likelihood phylogenetic tree based on partial nsP4 sequences. For comparison, sixty-two alphavirus sequences from different species were downloaded from GenBank, including the mosquito sequences previously reported in Uruguay (blue). Phylogeny was reconstructed under the GTR + Γ + I nucleotide substitution model. Mayaro virus was used as outgroup species. Clade supports were estimated through approximate likelihood ratio test (aLRT), and only those above 0.70 are shown. Accession numbers, bat species, and capture localities of the nine alphaviruses detected in this work are depicted in color: viruses found in Tadarida brasiliensis: orange; viruses found in Myotis spp.: red; capture sites: green; RNV and EEEV positive mosquitoes from Uruguay: blue.