American and Swiss scientists submitted papers on bioRxiv website, saying that they used the genome sequences of millions of COVID-19 that have been published to conduct research on its evolution in an unprecedented way, revealing the gene loci that COVID-19 must be in a specific state and can tolerate changes in order to survive. This discovery will help scientists to develop new drugs targeting some proteins of COVID-19. The researchers pointed out that by monitoring the growth of COVID-19 mutants, they may identify mutations in single base letters of viral RNA that are beneficial to the growth of the virus. These base letters are related to the four bases that constitute the backbone of the virus gene, but these single-letter mutations are only a small part of all possible mutations. Each single letter of RNA of COVID-19 may mutate 15000 times on average. Millions of COVID-19 sequencing samples provide researchers with a way to evaluate the results of these natural experiments. In the latest research, researchers from the Fred Hutchinson Cancer Center in the United States and the University of Basel in Switzerland used millions of published genome sequences of COVID-19 to first count the frequency of mutation at the site where all single letter mutations are known to be neutral. Because this will not lead to any change in the protein sequence, the results obtained will point out that without affecting the adaptability of the virus, The frequency of mutation at any site. Then, they compared the number of mutations observed at each site with the expected number, and mapped the results to all proteins of COVID-19 to reveal which sites must be in a specific state and which sites can tolerate changes in order for the virus to survive and spread. The researchers said that this discovery will help scientists to develop new drugs targeting certain proteins of COVID-19, which are not easy to escape the attack of existing drugs by mutation. (Xinhua News Agency)