AI Summary
Several SARS-CoV-2-related coronaviruses have been found in bats and pangolins, indicating a possible source of SARS-CoV-2. Some of these coronaviruses can bind to human ACE2 receptors, suggesting they may circulate in wildlife. Differences in bat ACE2 genes may affect the host range and tropism of these coronaviruses. One of these coronaviruses, B236, has been isolated from Laotian bats.
INTRODUCTIONA series of SARS-CoV-2-related coronaviruses (SC2r-CoVs), which are phylogenetically related to SARS-CoV-2, were identified in Rhinolophus bats in China and Southeast Asian countries. For example, RaTG13 (Rhinolophus affinis in China, 2013) (1), RmYN02 (Rhinolophus malayanus in China, 2019) (2), RacCS203 (Rhinolophus acuminatus in Thailand) (3), RpYN06 (Rhinolophus pusillus in China, 2020) (4), RshSTT182 (Rhinolophus shameli in Cambodia, 2010) (5), BANAL-20-236 (B236; Rhinolophus marshalli in Laos, 2020) (6), and Rc-o319 (Rhinolophus cornutus in Japan, 2013) (7) were reported so far. Also, SC2r-CoVs, such as Pangolin-CoV and MpCoV-GX, were identified in pangolins (8, 9). These findings support the concept that SARS-CoV-2 emergence is caused by the spillover of certain SC2r-CoV into humans. Importantly, the spike (S) proteins of some SC2r-CoVs, such as RaTG13 (10), B236 (6), and those identified in pangolins (11, 12), are capable of binding to human angiotensin converting enzyme 2 (ACE2), the receptor for SARS-CoV-2 infection. Therefore, it is plausible to assume that some SC2r-CoVs, which can bind to human ACE2, circulate in Rhinolophus bats and pangolins in the wild, particularly those residing in Southeast Asian countries. However, because bat ACE2 genes are highly diversified (13 – 15), it is hypothesized that the differences in bat ACE2 genes can affect the host range of SC2r-CoVs and further modulate the tropism of host ACE2 for the infection receptor.B236 is a replication-competent SC2r-CoV that was isolated from rectal swabs of Laotian R. marshalli by Temmam et al. (6) In this previous study, the viral sequences of BANAL-20-52 (B52) and BANAL-20-103