相同多态性位点对结核分枝杆菌北京家族菌株多位点可变数目串联重复序列基因型构成的影响

The effects on mycobacterial interspersed repetitive units-variable-number tandem repeat of loci with same allelic diversity in mycobacterium tuberculosis Beijing genotype strains

目的探讨多态性相同的位点对北京家族结核分枝杆菌多位点可变数目串联重复序列（MIRU-VNTR）基因分型的影响，为合理选择分型位点提供科学依据。方法分别选取9个及12个位点，构成4组MIRU—VNTR位点组合，其中，9位点组成的两个组合中，分别有两个不同位点（MIRU40／MIRUl6）多态性一致，其余为相同位点；12位点的两个组合则分别包括另外两个多态性相同的位点（MIRu39／MIRu31）。进行聚类分析，比较含有相同多态性的不同位点组合的分辨能力、成簇能力以及基因型特点。结果9位点两个组合都将菌株分为三群，其中，Ⅲ群菌株仅有1株相同，分别占组合1、2的2．0％和1．6％。12位点组合也将菌株分为三群，第Ⅱ群菌株组成差异非常明显，完全没有相同的菌株。结论多态性相同的位点对北京家族菌株MIRU—VNTR基因分型影响较大。在选择MIRU—VNTR分型位点时，应不仅仅检验位点的分辨能力和对成簇的影响，还应考虑有相同／相近多态性的位点对基因型构成的影响。

Qbjective To investigate the effects on mycobacterial interspersed repetitive units-variable- number tandem repeat（MIRU-VNTR） genotyping of loci with same allelic diversity in Mycobacterium tuberculo- sis Beijing genotype strains. Method R 2.9.1 software was used to construct phylogenetic tree based on two 9 and two 12 MIRU-VNTR loci combinations which have the same loci except MIRU40/MIRU16 and MIRU39/ MIRU31 respectively. The Hunter-Gaston index, cluster rate and the characteristic of genotype were analyzed of two combinations. Results The phylogenetic tree based on the two 9 loci combination can be both divided into three groups. There is only one identical strain in group Ⅲ which accounts for 2.0% and 1.6% in the two 9 lo- ci combinations, respectively. The phylogenetic tree based on the two 9 loci combination can be also devided into three groups. There is no identical strain in the three groups of the two 12 loci combinations. Conclusion Loci with the same allelic diversity have significant effects on MIRU-VNTR genotyping of Mycobacterium tuberculosis Beijing genotype strains. The effects on genotyping of loci that have the same or similar allelic diversity should also be considered besides the Hunter-Gaston index and cluster rate.