Researchers at Pasteur Institute in France collaborated with researchers from the University of Laos to look for viruses that resemble SARS-CoV-2, the coronavirus that caused COVID-19, among hundreds of greater horseshoe bats (Rhinolophus ferrumequinum).
The team found that these bats that live in the limestone caves in northern Laos carry coronaviruses that share a key feature with the virus that caused the COVID-19 pandemic, according to Bloomberg. They found three coronaviruses that matched receptor binding domains, which enzymes target to cause an infection.
Coronaviruses Closely Related to SARS-CoV-2 Exist in Nature
In the study titled "Coronaviruses With a SARS-CoV-2-Like Receptor-Binding Domain Allowing ACE2-Mediated Entry Into Human Cells Isolated From Bats of Indochinese Peninsula" published in the journal Nature, researchers showed that coronaviruses closely related to SARS-CoV-2 exist in nature.
Some species, such as Rhinolophus, carry a coronavirus that shares key features with SARS-CoV-2. This supports the idea that the virus that caused COVID-19 began from a spillover of a bat-borne virus.
Marc Eliot, study co-author and head of pathogen discovery at Pasteur Institute, said that the three viruses discovered, namely BANAL-52, BANAL-103, and BANAL-236, are the closest ancestors of SARS-CoV-2.
The three viruses and SARS-CoV-2 share receptor binding domains than the RaTG13 virus previously found in Rhinopholus affinis bats from Yunnan province, which was initially regarded as the closest match of SARS-CoV-2. The team wrote in the paper that the BANAL-236 virus specifically has an almost similar receptor-binding domain to the pandemic virus.
Researchers noted that they are now closer to finding the origins of the virus that caused COVID-19. "Eventually, with more sampling, the natural ancestry of the entire SARS-CoV-2 genome will be revealed," evolutionary biologist Edward Holmes from the University of Sydney wrote to Bloomberg via email.
The team noted that their findings point to a new presence of bat sarbecoviruses that may have a similar potential of infecting humans as the early strains of COVID-19.
Coronaviruses Transmitted to Humans From Animals 400,000 Times Every Year
According to a study cited in The Japan Times, hundreds to thousands of people may be infected with coronaviruses every year in China and Southeast Asia by animals that carry viruses related to SARS-CoV-2.
Researchers said that an average of 400,000 infections from spillover events might be recorded annually, but most of them would go unrecognized because of mild or no symptoms. More so, researchers said that they are not easily transmitted between people. But still, spillover events are an opportunity for a new disease outbreak similar to COVID-19.
Researchers aim to find communities in countries that are at risk of getting infected because of spillover events. Helping those communities reduce public health threats will also help the general public.
For instance, guano collectors or those people who spend their time in caves collecting bat guano in search of a nutrient-rich crop fertilizer are at risk of being exposed to bat-borne viruses. Further investigations are needed to assess whether these people have been infected by one of these viruses and developed antibodies that may protect against coronavirus infections.
However, Reuters reported that guano collectors seemed unfazed by the risk they faced. Bat guano collection has started generations ago and has helped boost crops and improved the taste of fruits.
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