At present, the new coronavirus has infected tens of thousands of people in our country, thousands of people died, and spread to more than 20 countries around the world. Confirming an intermediate host is critical to preventing further spread of the virus. Previously, researchers have suggested that bats or natural hosts of new coronaviruses, snakes and pangolins may be potential intermediate hosts.
On February 26, Liu Long of Hubei Medical College’s Affiliated People’s Hospital, in conjunction with Wu Jianguo of Guangzhou Jinan University, published a paper in the Journal of Medical Virology that the turtles (western turtles, green turtles, and Chinese dragonflies) may also be potential intermediate hosts for the transmission of the new coronavirus to humans.
The latest study uses the composition and differences of coronavirus protrusion proteins and host ACE2 receptors to predict the potential intermediate host of SARS-CoV-2.
The study focused on comparing the sequence of protrusions between SARS CoV-2 and SARS-CoV, bat SARS-like CoV, and other coronaviruses. This helps to perform evolutionary analysis and look for possible virus banks. In addition, the analysis of ace2 structure and combined base sequence pairs helps to provide clues to distinguish potential hosts.
The results show that the bat SARS-like CoV RaTG13 has 96.2% sequence homogeneity with the SARS-CoV-2 genome. It is worth noting that SARS-CoV is the most widely distributed coronavirus in pangolin specimens.
The interaction of protrusion RBD receptors is a key factor in determining the host range of coronaviruses. The team compared THE RBD sequence of protogenite proteins from SARS-CoV, bat or pangolin SARS-like CoV and SARS-CoV-2.
Bat SARS-like CoV is missing from 473 to 490 residuals, located in an external sub-structure, and it seems possible to determine whether these viruses do not naturally infect people. There is no direct evidence that BAT-like CoV has infected humans.
穿山甲SARS样CoV SRR10168377与蝙蝠SARS样CoV RaTG13仅具有85%的同一性。这表明如果只关注刺突RBD，穿山甲SARS样CoV SRR10168377有可能越过宿主屏障感染人类。
Similar to SARS-CoV and human ACE2, 31, 41, 82, 353, 355, and 357 residual squisomes on the receptor are positioned to the surface when interacting with SARS CoV-2 protrusion proteins.
From Asn501 in the RBD domain with ACE2 receptors 41 and 353 bits, turtles and pangolins appear to be closer to humans than bats. This suggests that turtles and pangolins may be potential extended hosts for SARS-CoV-2.
Understanding the mechanisms of structural integration will help to find an accurate virus library and help to develop prevention responses. The urgent analysis of the crystals of SARS-CoV-2 protrusion proteins through a frozen electron microscope helps to verify the binding point of the interaction between SARS CoV-2 protrusion RBD and human ACE2 or other host receptors.
It is reported that THE combination of SARS-CoV-2 protrusion protein and ACE2 is much stronger than THAT of SARS-CoV. This indicates that SARS-CoV-2 has more intermediate hosts.
Turtles are known to be a virus reservoir, carrying dozens of viruses, including the iris virus (RV), NV, papillomavirus (PV), fish iris virus (STIV), fish systemic sepsis globulin virus (STSSSV), Turtle small RIBO virus (ToPV) and Chinese haemorrhagic syndrome virus (TSHSV). Bat SARS-like CoV RaTG13 or other SARS-like CoV infections cannot be ruled out and transmitted to humans as evolution.
From SARS-CoV and MERS-CoV to SARS-CoV-2, bats are natural hosts of coronaviruses, but intermediate hosts are different. Previous studies have shown that snakes are likely to be a wildlife virus library of SARS-CoV-2 because of their synonymous use of the cositron relative (RSCU) compared to other animals.
Beavers and single-peak camels, as intermediate hosts of zoonotic SARS-CoV and MERS-CoV, live in different space-time environments, but they still transmit coronaviruses to humans. This makes it difficult to find an intermediate host for SARS-CoV-2 in the short term.
The analysis of viral receptor binding sequences and host receptors helps to quickly target possible intermediate hosts of SARS-CoV-2. Turtles on the market are more popular than illegally traded pangolins.
In summary, the study provides some information that, like snakes and pangolins, turtles (western turtles, green turtles, Chinese mussels) may also be potential intermediate hosts for spreading SARS-CoV-2 to humans, but further research is needed to confirm it.