动物源微小隐孢子虫分离株群体遗传结构研究

There are many species in the genus Cryptosporidium, among which, Cryptosporidium parvum plays an important role in the zoonotic transmission. Applicant research group has found the universality of Cryptosporidium parvum infection in dairy cattle in China, however, the genetic characteristics of C. parvum is unclear in the zoonotic transmission. In this project, the animal-derived C. parvum isolates collected and identified in the present laboratory are as the main research object. Ten to fifteen polymorphic gene loci will be selected and be used in the multilocus sequencde typing (MLST). According to the sequence data of MLST, the genetic polymorphism, the recombination frequence, the linkage disequilibrium, as well as the genetic difference degree among different animal populations will be calculated. The present project will focus on understanding the unique characterization of the population genetic structure and the genetic variation pattern of C. parvum isolates from various animals in China. The data obtained in this project should have direct significance in elucidating the biology, the transmission among different hosts, and the infection source of C. parvum. Moreover, This project will provide technical support for monitoring and tracing the infection source of foodborne/waterborne outbreak cases in China.

隐孢子虫属内虫种很多，其中微小隐孢子虫在人兽宿主共患传播中具有重要作用。申请人课题组已发现我国奶牛感染微小隐孢子虫的普遍性，但其人兽共患传播的遗传学特征尚不清楚。本项目以申请人课题组分离鉴定的动物源微小隐孢子虫分离株为主要研究对象，筛选10～15个多态性基因位点进行多位点序列分型（MLST），依据MLST数据计算微小隐孢子虫的遗传多态性、重组频率、连锁不平衡以及在不同动物群体间的遗传差异程度等，重点研究我国动物源微小隐孢子虫群体遗传结构的独特性及其遗传变异规律。研究结果对阐明微小隐孢子虫的生物学、在不同宿主间的传播以及感染来源等具有直接意义，同时为我国食源性/水源性暴发病例的监测和溯源等提供技术支持。

隐孢子虫属内虫种很多，其中微小隐孢子虫在人兽宿主共患传播中具有重要作用。本项目以动物源微小隐孢子虫分离株为研究对象，重点研究我国动物源微小隐孢子虫群体遗传结构的独特性及其遗传变异规律。. 首先开展了大量动物源隐孢子虫流行病学研究，采集河南和重庆山羊样品1265份、宁夏奶牛样品1580份、某隐孢子虫病暴发奶牛场252份、养殖场和周边农户啮齿动物232份、奶牛场苍蝇40组、新疆牧马样品262份，隐孢子虫感染率分别为3.48%、4.81%、21%、8.2%、10%。获得动物源微小隐孢子虫阳性分离株81个，研究结果进一步表明断奶前犊牛是微小隐孢子虫的主要储藏宿主。. 筛选12个微卫星、小卫星和SNP多态性位点对我国、瑞典和埃及不同动物源C. parvum IId共111个分离株进行MLST分型和群体遗传分析；鉴定出48个亚型，形成25个MLST亚型；发现C. parvum MLST亚型具有宿主适应性和地理区域隔离特点，鉴定出我国和瑞典C. parvum IId分离株为克隆性群体结构，结合牛羊驯化历史推论出C. parvum IId从西亚扩散至其他地理区域。该研究成果在C. parvum起源研究以及宿主适应机制研究方面是一个关键进展。. 本项目研究成果对阐明微小隐孢子虫的生物学、在不同宿主间的传播以及感染来源等具有直接意义，同时为我国食源性/水源性暴发病例的监测和溯源等提供技术支持。