A surge of new crown cases in foreign countries and the origin of the epidemic is still unknown

China's prevention and control measures for the new crown epidemic have been effective, but the situation outside China is not optimistic, "Diamond Princess" cruise ship epidemic has become the largest epidemic outside China When the world focused on China and Japan, the situation in South Korea, which had been relatively stable before, suddenly deteriorated, and the number of newly diagnosed cases doubled for three consecutive days According to South Korea's central anti epidemic strategy headquarters, from 16:00 on the 21st to 16:00 on the 22nd, there were 229 newly confirmed cases in South Korea, with 433 confirmed cases in total Among them, most of the new patients appeared in Daegu and qingshangbeidao areas, mainly affected by the occurrence of "super communicators" in Daegu and the collective infection events in hospitals in Qingbei area South Korean officials say they have made Daegu and gyeongbei, areas with severe outbreaks, a special management area for infectious diseases South Korean health workers spray disinfectants in front of hospitals The new crown epidemic has affected many countries in the world and spread rapidly in several countries outside China However, we do not know where the outbreak originated Although it was previously thought that sars-cov-2 originated from the seafood market in South China, a new research report of chinaxiv, a platform for pre release of scientific papers by the Chinese Academy of Sciences, overthrew this statement and pointed out that human to human transmission of SARS-CoV may have occurred as early as late November The report was jointly completed by Professor Yu Wenbin of Xishuangbanna Tropical Botanical Garden of Chinese Academy of Sciences and researchers from South China Agricultural University and Beijing brain center From the shared data of gisaid epiflutm database, the researchers obtained 93 complete genes of new coronavirus from 12 countries on 4 continents before February 12, 2020 and analyzed them to explore the evolution and transmission information of the virus since its discovery http://www.chinaxiv.org/abs/202002.00033 Sars-cov-2 did not mutate The genome of sars-cov-2 contains 140 variable loci, and the coding region contains 120 replacement loci, which are classified into 58 haplotypes (haploid genotypes) The researchers used 90 sars-cov-2 genomes to estimate the DNA replacement rate, and found that sars-cov-2 was lower than SARS-CoV and mers-cov, indicating that sars-cov-2 was still undergoing stable evolution without large-scale mutation caused by recombination with other viruses An overview of the overall comparison between 58 haplotypes and a representative of the outer group bat-ratg13-cov It was found that sars-cov-2 had two population expansions by using the software of Arlequin The time to calculate the expansion is 28.72 days (95% CI: 12.29-54.36 days), and the latest sampling date is February 3, 2020, so the most recent expansion occurred on January 6, 2020 In addition, the analysis of mismatch distribution of 22 genomes before January 6, 2020 shows that population expansion occurred on December 8, 2019, when only one infected patient was officially reported That is to say, sars-cov-2 had been transmitted from person to person in Wuhan before December, probably from the middle and late November China and foreign sample collection date The researchers proposed that bat-ratg13-cov was the outgroup of 58 haplotype evolution networks of sars-cov-2 The evolutionary relationship shows that haplotypes H13 and h38 are relatively "old" haplotypes, and they are associated with bat coronavirus ratg13 through an intermediate vector MV1 (maybe ancestral haplotype, or from intermediate host or patient No.0), and haplotype H1 is derived from haplotype H3 However, by tracing the virus samples corresponding to the haplotype, it is found that all the samples in the South China seafood market are H1 haplotypes or their derived haplotypes, indicating that this is not the original source of the virus, which may be caused by the workers or sellers in the market from other places Changes of the genome haplotypes of sars-cov-2 during sample collection The confirmation samples of South China market are indicated by red circle, and those unrelated to the market are indicated by blue circle In January 24, 2020, a novel coronavirus infection was first reported in Wuhan by the top international journal Lancet It was suggested that the origin of the virus may not be the Southern China seafood market The latest report reconfirmed this hypothesis through genome data analysis At the end of the report, the researchers believe that if more samples are sequenced in the future, H13 and h38, two ancestral haplotypes, will be found in the samples of some infected patients in Wuhan, which is very important for finding the original source of sars-cov-2 reference material: [1] Decoding evolution and transmissions of novel pneumonia coronavirus using the whole genomic data [2] South Korea today this scene Seoul mayor panicked: hurry home