Odongo D O, Oura C A L, Spooner P R, Kiara H, Mburu D, Hanotte O H, Bishop R P
International Livestock Research Institute, P.O. Box 30709, Nairobi 00100, Kenya.
Int J Parasitol. 2006 Jul;36(8):937-46. doi: 10.1016/j.ijpara.2006.01.008. Epub 2006 Mar 10.
Theileria parva schizont-infected lymphocyte culture isolates from western, central and coastal Kenya were analysed for size polymorphism at 30 T. parva-specific variable number tandem repeat (VNTR) loci using a panel of mini- and micro-satellite markers. The mean number of alleles ranged from 3 to 11 at individual loci and 183 distinct alleles were observed in total, indicating high genetic diversity within the T. parva gene pool in Kenyan cattle. The frequency distribution of the length variation of specific alleles among isolates ranged from normal to markedly discontinuous. Genetic relationships between isolates were analysed using standard indices of genetic distance. Genetic distances and dendrograms derived from these using neighbour-joining algorithms did not indicate significant clustering on a geographical basis. Analysis of molecular variance demonstrated that the genetic variation between individual isolates was 72%, but only 2.3% when isolates from different regions were pooled. Both these observations suggest minimal genetic sub-structuring relative to geographical origin. Linkage disequilibrium was observed between pairs of loci within populations, as in certain Ugandan T. parva populations. A novel observation was that disequilibrium was also detected between alleles at three individual pairs of VNTR loci when isolates from the three regional meta-populations were pooled for analysis.
利用一组微卫星和小卫星标记，对来自肯尼亚西部、中部和沿海地区的感染泰勒虫裂殖体的淋巴细胞培养分离株，在30个微小泰勒虫特异性可变数目串联重复（VNTR）位点进行大小多态性分析。各个位点的等位基因平均数在3到11之间，总共观察到183个不同的等位基因，这表明肯尼亚牛的微小泰勒虫基因库内具有高度的遗传多样性。分离株中特定等位基因长度变异的频率分布从正常到明显不连续不等。使用标准遗传距离指数分析分离株之间的遗传关系。基于这些数据使用邻接法得出的遗传距离和系统树图并未显示出基于地理因素的显著聚类。分子方差分析表明，各个分离株之间的遗传变异为72%，但将不同地区的分离株合并后，遗传变异仅为2.3%。这两个观察结果都表明，相对于地理起源，遗传亚结构最小。如同在某些乌干达微小泰勒虫种群中一样，在种群内的位点对之间观察到连锁不平衡。一个新的观察结果是，当将来自三个区域复合种群的分离株合并进行分析时，在三对个体VNTR位点的等位基因之间也检测到了不平衡。
