Fernando González Candelas
Professor of Genetics at the University of Valencia and researcher at the mixed unit Infection and Public Health FISABIO/Universitat de Valencia
This work builds on the previous discovery of novel coronaviruses in horseshoe bats from southern Russia. Many species of bats in this family harbour different coronaviruses and are the best candidates to represent the original host of SARS-CoV-2 before its jump to humans. Therefore, the question they set out to answer is whether these new viruses could infect individuals of our species.
To this end, they have carried out various tests with cell cultures and virus proteins, specifically the spicule and its cellular receptor-binding portion, to check whether the virus protein is capable of recognising and binding to different receptors present in human cells. The answer is that one of these viruses, the so-called Khosta2, is able to do so and, moreover, it recognises the same cellular receptor mainly used by SARS-CoV-2 to infect our cells, ACE2 (angiotensin-converting enzyme-2).
The result is not completely novel because other coronaviruses have also shown this capacity and some of them have been analysed in this work. The biggest surprise is that this ability is present in a virus that is not closely related to SARS-CoV-2, but belongs to a different lineage. The study highlights the great plasticity in the cellular receptor binding capacity of coronaviruses, including some that are related to human pathogens, such as SARS-CoV-1, and others that infect us but do not cause severe symptoms, such as HCoV-229E.
The discovery that SARS-CoV-2-like coronaviruses isolated from bats outside Southeast Asia could infect humans - it should be recalled that the tests have been conducted under laboratory conditions - represents a further wake-up call for the need to keep a close eye on new emerging pathogens even in areas of the planet that have not hitherto been considered to harbour relevant threats.