Canadian scholar: The new crown virus has been lurking in the population for 7 years.

Source: the genetic material of the new coronavirus was detected in the wastewater samples from Milan and Turin in December last year and Bologna in January this year, according to a report published on the official website of the National Institute of higher health of meis.subsequently, Spain also detected a new coronavirus from the waste water, which actually dates back to March last year.according to the Xinhua News Agency on June 28, researchers from the enterovirus team of Barcelona University tested the local wastewater samples in 2018 and 2019, and found that there were traces of new coronavirus in the wastewater collected on March 12 last year, but the virus level was very low, and all other samples were negative.alvert bosh, a biology professor who led the team, said that although the samples were exhausted and could not be repeated, the possibility of cross infection was avoided during the operation. Therefore, the results of this study suggest that similar situations are likely to occur in other parts of the world, i.e., many new coronal cases or covered up because they were misdiagnosed as influenza cases.at present, the United States, the Netherlands and other countries are also carrying out such research, in order to trace the possible epidemic time of the virus, and to explore the value of fixed-point monitoring of wastewater in response to epidemics.however, a recent phylogenetic analysis of the new coronavirus suggests that the new coronavirus may have evolved in the population for at least seven years from the perspective of S protein evolution.as a once-in-a-century pandemic, the new concept of highly infectious "suddenly" appears.previous phylogenetic analysis showed that its closest known evolutionary relative was a virus isolated from bats (ratg13). Therefore, it is generally believed that neocoronavirus also evolved from the ancestor virus of zoonosis, and has the ability to infect humans through gene mutation [possibly in the spike protein receptor binding domain (RBD)].so when did the new virus acquire the ability to recognize, combine and enter human cells for the first time? Researchers at the University of Calgary in Canada discussed this issue in a new study published on June 22, 2020 on biorxiv, a preprint server.detailed phylogenetic analysis, ancestral sequence reconstruction and molecular dynamics models were used to study the functional evolution of spike RBD spike protein of new coronavirus to confirm the origin of affinity between spike RBD spike protein variants and ACE2 receptor.the results showed that the preliminary phylogenetic analysis was consistent with previous studies - the genome similarity of the virus with bat coronavirus (ratg13) was 96%, and that of pangolin cov was 90%.the level Similarity Study between NCV and ratg13 (96.0% sequence identity) and pangolin cov (90.0% sequence identity) was conducted to analyze 479 NCV sequences collected from December 30, 2019 to March 20, 2020, and 16 variants were found.among them, 11 were missense mutations in 5% or more cases, and each variant had its own phylogenetic route.frequency of genomic variation of the new coronavirus. Then, the researchers tried to reconstruct the ancestral sequence of the spike RBD region so that they could identify the important mutations that specifically drive its recent adaptation to the human host.they reconstructed the common ancestor spike RBD sequence of all human infected virus strains, known as N1, and labeled the common ancestor of its closest animal virus ratg13 as N0.N1 is the same as spike RBD in the new crown reference sequence, while the spike RBD sequence of N0 is unique, reflecting the uniqueness of the new coronavirus source.the reconstruction of the ancestral sequence of spike RBD is different at four sites, namely, t346r, t372a, H / y498q and n519h. These four changes distinguish the evolved spike protein from the common ancestor of ratg13, which existed at least in 2013 (its offspring ratg13 was isolated in that year), which means N0 and N1 It covers at least seven years of molecular evolution. What are the functional differences between N0 and current spike RBD sequences? Starting from the X-ray crystal structure, the researchers carried out simulation experiments on spike-rbd-hace2 complex, which showed that the free binding energy of the complex decreased when N0 changed to N1. therefore, N0 to N1 actually reduces the affinity of spike RBD to ACE2 receptor. The functional evolution of sars-cov-2 spike RBD indicated that N0 strain had unexpectedly higher binding affinity than N1 strain. so why has it only recently emerged as a public health problem? One possibility is that although spike RBD can bind to ACE2 receptor, it may need other molecular components to help acquire new functions before infecting humans. the second possibility is that the virus may have been able to infect human cells for a long time in the past, but its ancestral form either causes less obvious clinical symptoms or is much less infectious (affecting only a few people). In either case, it has escaped the monitoring of the public health system, and the results of sewage testing in Spain and Italy seem to support this statement. this is the first study to show that the common ancestor of NCV and ratg13 has the ability to bind to human ACE2 receptor. this suggests that the new crown spike RBD does not seem to have recently evolved an affinity for binding to human receptor proteins, and this function seems to have been latent, indicating that the evolution of the disease is more complex than expected. in the future, in an ideal situation, a combinatorial library can be constructed and its function can be screened in order to understand the molecular mechanism of the virus's recent evolution in more detail. the current new coronal pandemic demonstrates the great unknown of Virology, which continues to challenge the ability of humans to remain healthy in the face of new coronal pathogens. virus traceability can help us to understand how a virus gradually infects human beings in the process of evolution, and provide evidence for human prevention and resistance against virus infection. Although there are many difficulties, it is very important for human health.