我国G2型人蛔虫和猪蛔虫的遗传多样性

Genetic diversity of Ascaris with the shared genotype G2 from humans and pigs in China

目的应用多个微卫星分子标记,对前期研究中运用ITS这一遗传标记未能区分的G2型人蛔虫和G2型猪蛔虫,进一步探讨其遗传多样性的差异。方法选用20个常染色体微卫星标记,结合毛细管电泳技术确定等位基因大小,使用软件CERVUS V2.0、ARLEQUIN V3.11、FSTAT V2.9.3和GENETIX V4.05对69个G2型人蛔虫和猪蛔虫样本进行遗传多样性分析。结果 G2型人蛔虫和猪蛔虫分别检出378和229个等位基因。20个基因位点中有14个位点在G2型人蛔虫和猪蛔虫中的优势等位基因一致。有18个位点中均存在G2型人、猪蛔虫各自的特有等位基因。G2型人蛔虫和猪蛔虫的平均期望杂合度分别为0.802和0.777,多态信息含量分别为0.779和0.737。分子变异方差分析(AMOVA)结果显示,遗传变异2.6%来自种群间,68.6%来自个体间,两蛔虫种群间FST值为0.0268,基因流(Nm)为9.08。结论 G2型人蛔虫和猪蛔虫均存在较高的遗传多样性,两者间无明显的遗传分化,并存在基因交流。但两者特有等位基因的差异和不同的优势等位基因的存在,提示其遗传上的重要差异,似可部分解释其宿主寄生特异性方面的不同。

To further discriminate Ascaris from humans and pigs with the shared genotype G2,20autosomal microsatellite markers together with capillary electrophoresis and the software CERVUS V2.0,ARLEQUIN V3.11,FSTAT V2.9.3 and GENETIX V4.05were used to analyze the genetic diversity of 69 Ascaris worms.Results showed that a total of 378different alleles were detected in Ascaris from humans and 229from pigs.There were 14sites out of the 20genetic loci having the same advantage alleles in Ascaris from both hosts,but special alleles of 18sites for each host derived fromAscaris.The average expected heterozygosities were 0.802and 0.777,and the polymorphism information content was 0.779and 0.737,respectively for Ascaris from humans and pigs.The analysis of molecular variation(AMOVA)showed 2.6% genetic variation between populations and 68.6% within individuals.The FSTestimates and gene flow(Nm)between two populations were 0.0268 and 9.08respectively.High genetic diversity was found in Ascaris from both hosts.No obvious genetic differentiation between the two populations was revealed and gene flow between them was detected.However,the differences in specific alleles and the advantage alleles suggested an important genetic difference,which might serve partly as an explanation for their different host affiliation.