Virology: SARS-CoV-2-related coronaviruses found in bats and pangolins in Southeast Asia

A coronavirus related to SARS-CoV-2 has been detected in bats from a wildlife sanctuary in eastern Thailand, reports a study in Nature Communications this week. Bats from this location, as well as a pangolin sampled from a wildlife checkpoint in southern Thailand, are shown to harbour antibodies that are able to neutralize SARS-CoV-2. These findings expand the geographical regions where SARS-CoV-2-related coronaviruses from bats and pangolins are found.

The origins of SARS-CoV-2 and the role of intermediate animal hosts have not yet been fully determined. The previous discovery of closely related coronaviruses from bats in China (notably RaTG13 and RmYN02, sharing 96% and 93.6% genome sequence identity with SARS-CoV-2, respectively) has suggested an animal origin for the emergence of SARS-CoV-2. Related coronaviruses have also been reported in samples from bats in Japan and pangolins in China, but immediate progenitor viruses and intermediate animal hosts have remained elusive.

Coronavirus surveillance investigations carried out by Lin-Fa Wang and colleagues identify a close relative to SARS-CoV-2 in five acuminate horseshoe bats (Rhinolophus acuminatus) from an artificial cave in a wildlife sanctuary located in Eastern Thailand. The isolated virus, named RacCS203, exhibits 91.5% genome similarity to SARS-CoV-2 and it is also closely related to RmYN02. Sequence analysis of the receptor binding domain of the Spike protein, coupled with ACE2 binding studies, suggest that RacCS203 is unable to use the human ACE2 receptor to enter host cells. The detection of SARS CoV-2 neutralizing antibodies in bats of the same colony and in a pangolin at a wildlife checkpoint in southern Thailand also provides evidence for the circulation of SARS-CoV-2-related coronaviruses in Southeast Asia.

The authors note that their sample size and area is limited, but they predict that SARS-CoV-2-related coronaviruses may be present in bats across many nations and regions in Asia. Although these findings do not pinpoint the origins of SARS-CoV-2, they extend the area in which SARS-CoV-2 relatives have been detected to a distance of around 4,800km.