基于几丁质酶基因序列分析鉴定兔源须癣毛癣菌

Identification of Trichophyton mentagrophytes in Rabbit based on the Chitinase Gene Sequence Analysis

利用几丁质酶基因(CHS1)序列分析和形态学方法对兔源须癣毛癣菌分离株(31株)进行鉴定和分型。从患兔采集病料,在沙保弱培养基进行分离培养,观察菌落和菌丝、孢子的形态及尿素酶、毛发穿孔等生理试验表现;提取病料和分离株DNA,扩增目的基因,通过序列分析,结合形态学方法对分离株进行鉴定,根据分离株序列同源性差异进行基因分型。结果显示,分离株的菌落多数为颗粒型和粉末型,占87.09%(27/31),背面有黄褐色素沉着,有大量葡萄状小分生孢子、螺旋菌丝、梳状菌丝及棒状大分生孢子,尿素酶试验和毛发穿孔试验阳性;CHS1序列比对显示分离菌株与须癣毛癣菌复合体的指间须癣毛癣菌有99.2%~95.4%相似性。根据CHS1序列比对结果,结合分离株的形态学特征,将该菌株鉴定为亲动物指间须癣毛癣菌。基于CHS1序列同源性差异,将分离株分成5种基因类型,其中Ⅰ型和Ⅱ型是优势菌株,占54.84%(17/31),提示CHS1序列分析可以用于须癣毛癣菌的鉴定和基因分型。

It was conducted to identify the gene type of 31 Trichophyton mentagrophytes isolated from rabbits.Samples were collected from infected rabbits for cultivation experiments on Sabouraud′s medium.Isolates were identified by morphology,urease test,hair perforation test and DNA analysis,and then subjected to phenotyping analysis by CHS1 gene sequencing.Results showed that 87.09%(27/31)of the colonies were granular-and powder-like with yellow-brown pigmentation deposition.Numerous grape-like microconidia,spiral hyphae,pectinafe mycelium and club-shaped macroconidia were presented in the culture.Urease test and hair perforation test were positive.The CHS1 sequences of the isolates showed 99.2%-95.4% homology with Trichophyton interdigitale.The results indicate that the isolates obtained in the present study are most likely zoophilic Trichophyton interdigitale.Based on the CHS1 gene variations in sequences,the isolates were divided into 5genotypes.The typeⅠ and typeⅡ were the dominant genotypes,which accounted for 54.84%(17/31)of the isolates.These results suggest that analysis of CHS1 sequences is useful for identification and typing of Trichophyton mentagrophytes.