# Integrated molecular and metatranscriptomic evidence of Tacaribe virus and the brain virome profile of Molossus molossus bat sampled in Brazil

## TL;DR

Researchers found Tacaribe virus in an insect-eating bat species in Brazil, expanding the known host range and highlighting the need for broader virus surveillance.

## Contribution

First detection of Tacaribe virus in an insectivorous bat species, expanding its known host and tissue range.

## Key findings

- Tacaribe virus was detected in multiple biological compartments of Molossus molossus bats.
- Phylogenetic analysis grouped the virus with other divergent arenaviruses from different bat species.
- Untargeted sequencing revealed unexpected viral diversity in non-traditional hosts.

## Abstract

Tacaribe virus (TCRV), a New World arenavirus, is associated with neotropical frugivorous bats, particularly Artibeus spp., and is considered to have zoonotic potential. Here, we report the detection of TCRV in multiple biological compartments of a Molossus molossus (velvety free-tailed bat), an insectivorous species commonly found in Brazilian urban ecosystems. Brain tissues negative for rabies were subjected to high-throughput RNA sequencing, revealing a diverse array of viral taxa, including partial L and S segments of TCRV with respective genome coverages of 68.2% and 65.6%. These sequences shared 90% nucleotide identity and 94% amino acid identity with TCRV reference strains. Phylogenetic reconstruction grouped the newly identified TCRV sequences and the TCRV strain A354 (isolated from a Brazilian Artibeus planirostris bat) within a clade that also includes Tietê mammarenavirus strains (Brazilian Carollia perspicillata bat), both of which are genetically divergent members of the Arenaviridae family. The detection of TCRV in M. molossus may indicate previously unrecognized circulation of this virus in insectivorous bats, expanding our understanding of its tissue tropism and host range. This finding is particularly significant given the synanthropic behavior of M. molossus bats and its potential implications for TCRV evolution. Moreover, our results highlight the critical role of untargeted high-throughput sequencing in uncovering overlooked viral diversity, enabling the detection of unexpected pathogens in non-traditional hosts and tissues. While TCRV remains poorly characterized in terms of human pathogenicity, continued surveillance is warranted to assess potential spillover risks.

Understanding which animals carry viruses is key to predicting and preventing disease spread. Here, we report the first detection of Tacaribe virus (TCRV), previously found only in fruit-eating bats, in multiple biological compartments, including the brain, of Molossus molossus, an insect-eating bat common in urban areas of Brazil. This finding expands the known range of both the virus and its possible hosts. By confirming this unexpected host-virus association using original tissue samples, our study provides new insights into how TCRV may circulate in nature. While TCRV is not currently considered a major threat to humans, its detection in a new bat species raises important questions about its transmission, evolution, and potential health impacts. These results emphasize the importance of monitoring diverse bat species, including those not traditionally linked to specific viruses, to better assess emerging virus risks in changing environments.