论文部分内容阅读
目的比较SARS冠状病毒(SARS-CoV)与第1至第3组(其他3组)冠状病毒的中性突变速率之异同,为更深入研究SARS-CoV起源提供新的思路。方法在美国国立生物技术信息中心中获取其他3组26条病毒序列,同时选取7条SARS-CoV序列。计算各病毒株5个主要基因串联序列的同义替换核苷酸的数量(Ks值),以此值与时间创建散点图,并进行直线拟合,取得各自中性突变速率并比较。结果 SARS-CoV中性突变速率为7.33×10-6/位点.天,而其他3组冠状病毒为2×10-6/位点.天,仅约前者的1/3.5,但决定系数R2极低,无意义。经多种拟合检验,发现标本量和离散性不是本文R2低值的主要原因。结论用同一方法对SARS-CoV和其他3组冠状病毒的中性突变速率进行比较研究,结果显示两者明显不同或具不同的模式;提示和其他3组冠状病毒相比较,SARS-CoV在分子进化或起源模式上似有特别之处。
Objective To compare the similarities and differences between SARS coronavirus (SARS-CoV) and neutral mutants of Group 1 to 3 (other 3 groups) coronavirus, and to provide new ideas for further studying the origin of SARS-CoV. Methods The other 3 groups of 26 virus sequences were obtained from the National Center for Biotechnology Information of the United States. Seven SARS-CoV sequences were also selected. Calculate the number of synonymous nucleotide substitutions (Ks) of the five major genes in each strain, and then create a scattergram with this value and time, and perform linear fitting to obtain the respective neutral mutation rates. Results The rate of neutral mutation in SARS-CoV was 7.33 × 10-6 / site day, while the other 3 groups of coronavirus were 2 × 10-6 / site, only about 1 / 3.5 of the former, but the coefficient of determination R2 Very low, meaningless. After a variety of fitting tests, found that the sample size and discreteness is not the main reason for the low value of R2. Conclusions The same method was used to compare the neutral mutation rates of SARS-CoV and other three groups of coronaviruses. The results showed that the two were significantly different or had different patterns; suggesting that compared with other three groups of coronaviruses, SARS- There may be something special about evolution or origins.