Khosta-2 virus, belonging to the same family as SARS-CoV-2, was isolated in 2020 near Sochi in Russia. Today we know more about its characteristics, such as its ability to use the ACE-2 receptor and to resist anti-SARS-CoV-2 antibodies.
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The batsbats they are the natural reservoir of many viruses. The monitoring and study of these by scientists allows them to be better known and to anticipate a potential zoonotic event. In 2020 two viruses of the subgenus Sarbecovius, the same as the SARS-CoV-2SARS-CoV-2, were isolated from horseshoe bats in Russia, near the Sochi National Park. Khosta-1 and Khosta-2 belong to the cladeclade 3 which includes only animal viruses, while SARS-CoV 1 and 2 are included in clade 1. To date, no human infections caused by Khosta virus are known. Sabercoviruses use the proteinprotein ACE-2 to infect cells, so this ability was tested for Khosta-1 and Khosta-2 in a study recently published in Pathogenic plos.
Khosta-2, a threat to humans?
To find out whether Khosta-1 and 2 use the ACE-2 receptor, the scientists worked only with the viral fragment that interacts with said receptor, the RBD, grafted onto pseudoviruses. In vitro, Khosta-1 fails to infect cultured cells expressing the human ACE-2 receptor, however, Khosta-2 does and in the same proportions as RaTG13, a clade 1 bat virus similar to SARS-CoV-2. Further experiments indicate that the Khosta-2 protein S is also capable of interacting with ACE-2.
The scientists then tested the ability of the antibodies present in the serum of people vaccinated against COVID-19COVID-19 neutralize a pseudovirus carrying Khosta-2 protein S. The results show that Khosta-2 protein S is resistant to vaccinee sera. Not surprisingly, the S proteins of Khosta-2 and SARSCoV-2 are only 60% identical; this is not enough for anti-SARS-CoV-2 antibodies to recognize Khosta-2 and generate protection against it. In light of the data available today, there is no reason to worry about a new zoonotic event caused by Khosta-2.
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