Turtles may be potential intermediate hosts for SARS-CoV-2

Reporter : Wang Ruixue / Publisher : China Science News

http://news.sciencenet.cn/htmlpaper/2020/3/2020328241767555186.shtm

Translation, editing : Gan Yung Chyan, KUCINTA SETIA

 Image below : Chinese soft-shelled turtle (Pelodiscus sinensis), part of the turtle family, may be a potential intermediate host for SARS-CoV-2. Video Screenshot.

On 26 February 2020, Liu Long from the People’s Hospital of Hubei Medical College and Wu Jianguo's research team from Jinan University in Guangzhou published a paper in the Journal of Medical Virology, saying that turtles (western painted turtle, green sea turtle, Chinese soft-shelled turtle) (Chrysemys picta bellii, Chelonia mydas, and Pelodiscus sinensis) may also be the potential intermediate host for the spread of SARS-CoV-2 to humans. Researchers predicted the potential intermediate host of the covi based on the composition and difference of the coronavirus spike protein and the host ACE2 receptor.

The focus of the study is to compare the spike sequences between the new coronavirus and SARS-CoV, bat SARS-like CoV and other coronaviruses. This facilitates evolutionary analysis and searches for possible virus libraries. In addition, the analysis of ACE2 structure and binding motif alignment can help provide clues to distinguish potential hosts.

The results of the study showed that the bat SARS-like CoV RaTG13 has 96.2% sequence identity with the entire genome of the new coronavirus. It is worth noting that SARS-CoV is the most widely distributed coronavirus in pangolin specimens.

The research team also compared the RBD sequences of the spike protein from SARS-CoV, bat or pangolin SARS-like CoV and the new coronavirus. The researchers said that bat SARS-like CoV is missing from the 473th to the 490th residues and is located in the outer subdomain. It seems that these viruses will not naturally infect humans.

The 329-521 RBD sequence of SARS-CoV-2 has 93% homology with pangolin SARS-like CoV SRR10168377, which is higher than 89% of bat SARS-like CoV RaTG13, but the latter two have only 85% homology. This indicates that if only focusing on the spike RBD, pangolin SARS-like CoV SRR10168377 may cross the host barrier and infect humans.

The researchers said that from Asn501 in the RBD domain with positions 41 and 353 of the ACE2 receptor, turtles and pangolins seem to be closer to humans than bats. This shows that like snakes and pangolins, turtles may also be potential intermediate hosts for the transmission of SARS-CoV-2 to humans, but further research is needed to confirm.

Related paper information: https://onlinelibrary.wiley.com/doi/abs/10.1002/jmv.25726