一个具有诊断价值的弓形虫基因的发现

目的用弓形虫成囊株感染的小鼠血清筛选弓形虫RH株速殖子cDNA文库，以寻找诊断弓形虫病的抗原基因。方法收集成囊株(Prugniaud株)慢性感染的小鼠血清，经滤膜吸附法去除大肠杆菌抗体，筛选弓形虫RH株速殖子cDNA文库。对3次复筛得到的阳性克隆进行插入片段的核苷酸序列测定，结果送GenBank进行同源性分析。根据序列测定结果，选取其中1个具有完整开放阅读框架的基因进行分析。结果获得4个持续阳性反应克隆。测序和同源性分析显示，WT1为弓形虫P30基因；WT4为弓形虫N-乙酰磷酸丙糖转移酶基因；WT9与已知的基因无同源性。WT12克隆基因与一未知的弓形虫基因有很高的同源性，且具有1个513bp大小的完整开放阅读框架，其蛋白质结构和功能预测可能是1个跨膜信号蛋白。结论筛选得到的1个阳性克隆有望成为早期诊断抗原基因，值得进一步研究。

Discovery of a Diagnotic Gene of Toxoplasma Gondii

Objective To screen the cDNA library of toxoplasma gondii tachyzoite stage ( RH strain) by using sera of mouse infected with bradyzoites (Prugniaud strain) in order to find the antigens of early diagnosis.Methods The sera of mouse were collected and anti-E.coli antibodies were removed by absorption with E.coli lysates. The sera were used to screen cDNA library constructed. The positive clones from rescreening three times were sequenced.The obtained genes were compared in GenBank database. A sequenced gene which has complete open reading frame was analysed by bioinformatics softwares. Results The four positive clones were obtained by immunoscreening T. gondii cDNA library. WT1 clone is T. gondii P30 gene and WT4 clone is phosphatidylinositol N-acetylglucosaminyltransferase subunit C gene. The sequence of WT9 has no significant similarity with the genes submitted. WT12 clone has 649 bp and a 513 bp-sized complete open reading frame(ORF). The bioinformatics analysis predicted that the gene might be related to transmembrane signal protein. Conclusion One of the positive clones was obtained by immunoscreening of T.gondii cDNA library which may have a potential significance of the dignosis of toxoplasmosis.