A study suggests that bats are an underestimated reservoir for arenaviruses

A study suggests that bats are an underestimated reservoir for arenaviruses

In a recent study published in the journal of the US Centers for Disease Control and Prevention (CDC). Emerging infectious diseases a team of researchers reported the detection of arenavirus ribonucleic acid (RNA) from various bat species sampled in Brazil between 2007 and 2011.

Lernen: Sehr unterschiedliche Arenaviren in neotropischen Fledermäusen, Brasilien. Bildnachweis: Kateryna Kon/Shutterstock

background

Of the four genera of the virus family Arenaviridae, Mammarenavirus is the only genus that infects mammals. The genus is divided into the New World arenaviruses and the choriomeningitis-Lassa virus serocomplex, which are distributed worldwide. Some New World arenaviruses, such as Junin, Chapare, Guanarito, Machupo, and Sabia viruses, cause hemorrhagic fever in humans.

While the pathogenic arenaviruses are generally transmitted to humans through infected rodents, Tacaribe mammarynavirus, which is found in bats and is not infectious to humans, is anecdotally known to cause flu-like symptoms. Although bats are known to harbor zoonotic viruses, there is limited epidemiological evidence for the association between bats and arenaviruses, consisting primarily of a single isolated virus and experimental infections of bats.

However, since Tacaribe virus belongs to the same group as the hemorrhagic fever-causing viruses, which also exhibit immune evasion and cell tropism, the possibility of serious infections caused by Tacaribe virus cannot be excluded.

About studying

In the present study, researchers collected bat samples from southeastern Brazil and analyzed spleen, lung, intestine, kidney and liver tissues from the samples. They collected a total of 1,047 bats from 32 species and analyzed 3,670 tissue samples. To detect arenavirus RNA, they performed reverse transcription-polymerase chain reaction (RT-PCR) with modified primers to amplify partial sequences of the RNA-dependent RNA polymerase gene of New World arenaviruses.

In addition, they used Illumina-based deep sequencing to obtain complete arenavirus coding sequences from two of the collected bat species. The sequences obtained from RT-PCR and the complete coding sequences were used for phylogenetic analyzes and to determine the homogeneous sequence distances.

Results

The results showed arenavirus RNA from 1.62% (17 of 1047) of the bats examined, belonging to three species - one Artibeus planirostris, four Artibeus lituratus and 12 Carollia perspicillata. The viruses from the two Artibeus species were identified as Tacaribe mammarenavirus, while the virus detected in the 12 samples of Carollia perspicillata was identified as a new species, which the authors named Tietê mammarenavirus.

All samples were collected in forested and urban areas within 60 km of each other, indicating a possible viral reservoir in bats in the region. Similar levels of virus were found in tissues from the spleen and lung, suggesting a systemic infection. The highest concentration of arenavirus was found in an intestinal tissue sample, suggesting enteric viral excretion.

Phylogenetic reconstruction based on the partial RNA-dependent RNA polymerase gene sequences revealed two clades of New World arenaviruses in Brazil. The arenaviruses from the two Artibeus species formed one clade, while the sequences from the Carollia perspicillata samples formed another clade. The complete coding sequences showed an identical genome organization to other mammarenaviruses and formed a monophyletic group with Tacaribe virus that was well supported.

The maximum likelihood tree using the complete genes for large segments recovered the entire clade containing the Tacaribe virus and sequences from Brazil as sister to the Junin and Machupo New World arenaviruses.

However, phylogenetic analysis using the complete small segment genes showed a sister relationship between the Ocozocoautla de Espinosa virus and the clade containing the Brazillian sequences and the Tacaribe virus sequences.

The Ocozocoautla de Espinosa virus is believed to have caused an outbreak of hemorrhagic fever in Mexico. Furthermore, recombination analyzes and sequence distances did not indicate recombination events.

The taxonomic assessment of the new virus species from the Carollia perspicillata samples was based on pairwise sequence comparisons with Tacaribe virus, showing a nucleotide sequence identity of less than 80% and a nucleocapsid protein amino acid identity of 88.6% to 90% and the presence of a distinct host. The species was named after a river near the sampling site.

Conclusions

In summary, the study examined bat species collected in southwestern Brazil for the presence of arenavirus RNA using sequence amplification methods. The results showed the presence of arenavirus RNA from three bat species, accounting for 1.62% of the total sample size.

The phylogenetic analyzes revealed that the arenaviruses detected in the bat samples are closely related to Tacaribe virus, a New World arenavirus found in bats. One of the detected arenaviruses is a new species and was named Tietê Mammarenavirus.

While New World arenaviruses are generally found in rodents, the results of this study suggest that bats may be arenavirus reservoirs and need to be further explored.

Reference:

• Góes LGB, Fischer C, Campos ACA, de Carvalho C, Moreira-Soto A, Ambar G, et al. (2022) Hochgradig vielfältige Arenaviren in neotropischen Fledermäusen, Brasilien. Neu auftretende Infektionskrankheiten. doi: https://doi.org/10.3201/eid2812.220980 https://wwwnc.cdc.gov/eid/article/28/12/22-0980_article

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