Molecular mechanisms of diversity of theileria parasite genes and control of the disease

他们的大肠杆菌是一种蜱传播的牛原生动物。良性牛肠杆菌寄生虫分布于亚洲国家，被认为属于塞真特绦虫/水牛/东方绦虫群。该寄生虫具有主螺质表面蛋白（MPSP）基因，该基因是寄生虫逃避宿主免疫的手段之一。为了进一步了解两种寄生虫的基因组定位，我们利用文库中随机cDNA克隆的表达序列标记（EST）测序方法，对由细小梭菌转化的t淋巴母细胞细胞系中表达的牛基因进行了鉴定。对394个cDNA克隆进行单次测序，并在GeneBank、EBML和DDBJ数据库中寻找显著同源性。数据库中有141个克隆与基因具有显著的同源性。大多数ESTs（47条）与人类序列同源，只有少数（19条）与牛序列同源。126个克隆与数据库序列不匹配，可能代表新的转录本。EST测序方法最近在发现几种寄生虫的新基因方面做出了巨大贡献。因此，我们对小孢子虫分裂期的461个cDNA克隆进行了测序。cDNA克隆被定位到4-T上。其中20个克隆与parva T.parva基因组的33个Sfil片段相对应。EST测序显示了其在寄生虫这一阶段鉴定新基因的潜力，并为将EST添加到T.parva数据库做出了巨大贡献。所报道的序列数据对细小单胞虫基因组定位和它们的大肠杆菌寄生虫的比较基因组定位具有宝贵的价值。

Theileria sergenti is a tick-borne protozoa of cattle. Benign bovine theileria parasites, which are presumed to be of the T.sergenti/buffeli/orientalis group are distributed in Asian countries. The parasites have the major piroplasm surface protein (MPSP) gene which is one of the means of parasite evasion of host immunity. T.sergenti has 4 chromosomes similar to T.parva.Most of genes used for molecular karyotype showed a conserved synteny between T.sergenti and T.parva.To underatand the genome mapping of theileria parasites, characterization of bovine genes expressed in T.parva transformed T-lymphoblastoid cell lines was performed by using expressed sequence tag (EST) sequencing approach of random cDNA clones from libraries. Single pass sequencing was done on 394 cDNA clones and the sequences search for significant homolgies in GeneBank, EBML and DDBJ databases. About 141 clones showed significant homology to genes in the databases. The majority of these ESTs (47) showed homology to human sequences and only a few (19) matched bovine sequence. 126 clones did not match database sequences and may represent novel transcripts.The EST sequencing approach has recently contributed tremendously to discover of new genes in several parasites. Thus, we performed the sequencing of 461 cDNA clones from the schizont stage of T.parva. The cDNA colnes were mapped to the 4-T.parva chromosomes and 20 of these clones were mapped to the 33 Sfil fragments of the T.parva genome. EST sequencing demonstrated its potential in the identification of new genes in this stage of the parasite and has contributed greatly to the addition of ESTs into the T.parva database. The sequence data reported is invaluable for T.parva genome mapping and in the comparative genome mapping of theileria parasites.