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目的 研究环形泰勒虫表面蛋白(TaSP)在中国分离株中的多态性.方法 将来自内蒙古自治区、宁夏回族自治区和新疆维吾尔自治区的3个环形泰勒虫分离株在RPMI 1640培养液中进行培养, PCR扩增裂殖体基因组DNA中TaSP基因并进行测序.测序结果用Clustal W2多序列比对软件进行分析,应用在线生物软件进行蛋白质分子组成和基元的预测.结果 3个中国分离株TaSP氨基酸序列比对表明,被称为高免疫原性区的中央部分(第38-161个氨基酸)无论在长度还是氨基酸序列组成上均呈多态性, 而N-末端(前37个氨基酸)和C-末端(最后154个氨基酸)极端保守.系统进化树和同源百分比分析表明,中国分离株与土耳其分离株具有较近的亲缘关系,而与印度、摩洛哥和突尼斯分离株差异较大.更为重要的是,在中国分离株之间TaSP存在变异性.这种变异性引起不同分离株间在某些基元,特别是酪蛋白激酶Ⅱ磷酸化位点的分布和数量上的变化.结论 环形泰勒虫TaSP在不同的中国分离株中具有多态性.“,”Objective To study the TaSP polymorphism in three Chinese isolates of Theileria annulata. Methods The isolates from Inner Mongolia Autonomous Region, Ningxia Hui Autonomous Region and Xinjiang Uygur Autonomous Region were cultured in RPMI 1640 medium. TaSP gene was amplified from genomic DNA extracted from schizonts using polymerase chain reaction (PCR) and sequenced. Its amino acid sequence comparison was carried out with Clustal W2 multiple sequence alignment program. Molecular component and motif prediction were performed with online servers. Results The comparison of TaSP amino acid sequences of the three isolates showed that the central region (aa position 38-161) predicted to be the highly immunogenetic domain was polymorphic both in size and amino acid sequence, while the N-terminal (first 37 aa) and C-terminal (last 154 aa) parts were strongly conserved. Phylogenetic analysis and percentage identity revealed that the Chinese isolates were closely related to the isolates from Turkey, but quite different from those of India, Morocco and Tunisia. More importantly, variability was noticed among Chinese isolates, which caused both the location and number′s differences of motif (casein kinase II phosphorylation sites) among three TaSP sequences. Conclusion TaSP polymorphism exists in the Chinese isolates of T. annulata.