by André Julião, FAPESP

Insect-eating bat of the species Molossus molossus in which were found a novel coronavirus in South America, closely related to MERS-CoV, and a human-associated gemykibivirus. Credit: Larissa Leão Ferrer de Sousa

A collaboration between researchers in the Brazilian states of São Paulo and Ceará and colleagues affiliated with Hong Kong University (HKU) in China has resulted in the discovery of a novel coronavirus in bats, the first in South America closely related to the virus that causes Middle East respiratory syndrome (MERS-CoV).

An article describing the discovery is published in the Journal of Medical Virology (JMV).

"Right now we aren't sure it can infect humans, but we detected parts of the virus's spike protein [which binds to mammalian cells to start an infection] suggesting potential interaction with the receptor used by MERS-CoV. To find out more, we plan to conduct experiments in Hong Kong during the current year, " said Bruna Stefanie Silvério, first author of the article.

The researchers identified seven coronaviruses in 5 out of 16 oral and rectal swabs from bats collected by the Central Health Laboratory (LACEN) of Ceará in Fortaleza, the state capital. The article highlights the significant genetic diversity of the coronaviruses in question. The five bats belonged to two different species (Molossus molossus, an insectivore, and Artibeus lituratus, a frugivore).

In an earlier study by the groups at LACEN Fortaleza and UNIFESP, rabies virus variants closely related to variants present in marmosets were found in bats.

"Bats are important viral reservoirs and should therefore be submitted to continuous epidemiological surveillance. This monitoring helps identify circulating viruses and risks of transmission to other animals, and even to humans, " said Ricardo Durães-Carvalho, last author of the article, a professor at EPM-UNIFESP and Silvério's thesis advisor.

Durães-Carvalho is principal investigator for the project "Bats: epidemiological surveillance, high-resolution phylodynamics, search and design of peptides of biotechnological interest in emergent and reemerging viruses."

MERS-CoV

The MERS coronavirus was first identified in 2012 in Saudi Arabia. In total, 27 countries have reported cases since 2012, leading to 858 known deaths due to the infection and related complications.

In the viruses they found, the Brazilian researchers identified a genetic sequence with 71.9% similarity to the MERS-CoV genome. The gene that encoded the spike protein exhibited 71.74% similarity with MERS-CoV's spike protein, which was isolated from humans in Saudi Arabia in 2015.

To find out whether it can bind to human cells, experiments will have to be conducted at high-biosecurity laboratories. These trials are scheduled to take place at HKU during 2025.

Same bat, different virus

A previous paper published in JMV by the same group of researchers reported the detection of a human-associated gemykibivirus-2 in one of the M. molossus bats analyzed at LACEN Fortaleza.

According to the authors, it was highly similar to a gemykibivirus identified in samples of human cerebrospinal fluid. The same virus was also identified in samples from blood banks.

Previous research detected the gemykibivirus in patients with HIV, sepsis of unknown origin, recurrent pericarditis, and unexplained cases of diarrhea and encephalitis. This is the first time the virus has been identified in bats.

Discovery of the virus required the development of novel primers (short single-stranded RNA molecules used in genomics to initiate DNA synthesis). In this case, the primers were based specifically on the genetic sequence from the gemykibivirus detected in humans.

"A lack of viral sequences available from databases prevented us from analyzing these viruses in greater depth. At the same time, the fact that we identified such little-known viral agents makes our findings a basis for future investigations, " Silvério said.

Durães-Carvalho concurred. "Our studies show the importance of making this type of analysis more systematic, optimized and integrated, with several sectors participating and generating data on unified platforms that can be used by health systems to monitor and even prevent epidemics and pandemics, " he said.

More information: Bruna Stefanie Silvério et al, Coronavirus Cryptic Landscape and Draft Genome of a Novel CoV Clade Related to MERS From Bats Circulating in Northeastern Brazil, Journal of Medical Virology (2025). DOI: 10.1002/jmv.70173