新生隐球菌格鲁比变种国内菌株的多位点微卫星灶分型

Multilocus microsatellite typing for the domestic strains of Cryptococcus neoformans var. grubii

目的应用多位点微卫星灶分型(MLMT)对国内6个城市分离出的新生隐球菌格鲁比变种(Cryptococcus neo-formans var.grubii)进行基因分型,了解该变种的国内基因型分布特征。方法提取已鉴定的43株新生隐球菌格鲁比变种DNA,用PCR对3个微卫星位点(CNG1,CNG2,CNG3)的基因片段进行扩增后测序。再计算每一菌株位点基序重复数(CNG1对应TA重复,CNG2对应GA重复,CNG3对应CAT重复);据基序重复数判定各菌株的基因型。结果所有43株菌中,MLMT-17型占83.72%,该型在临床和环境的菌株中分别占86.67%和70%。MLMT-39、-40是新发现的基因型。结论在我国,MLMT-17是最常见的新生隐球菌格鲁比变种基因型,普遍存在于临床和环境菌株中,表明国内临床新生隐球菌病的感染菌株主要源于本土环境菌株。

Objective Cryptococcus neoformans var. grubii isolates from 6 different cities in our country using multilocus microsatellite typing （MLMT） method were genotyped to explore the genotypic distribution of the variety. Methods The DNA of forty-three isolates of Cryptococcus neoformans var. grubii was extracted. The DNA frag-ments covering microsatellite loci CNG1, CNG2 and CNG3 were amplified using PCR, and then sequenced. The numbers of each motif repeat in 3 microsatellite regions （“TA” repeats for CNG1, “GA” repeats for CNG2, and “CAT” repeats for CNG3 ） were calculated. According to the repeat numbers of these motif, the MLMT types of 43 strains of Cryptococcus rteoformans var. grubii were determined. Results Out of 43 isolates, the percentage of MLMT-17 was 83.72%. In the clinical and environmental isolates, the percentages of MLMT-17 were 86.67% and 70%, respectively. Two new genotypes MLMT-39 and -40 were found. Conclusion MLMT-17 of Cryptococcus neoformans vat. grubii is prevalent in both clinical and community environment in China. Implying the most clinical strains which resulted in cryptococcosis originated from indigenous environmental strains.