Kron M A, Ali M H
Michigan State University, Department of Medicine, East Lansing.
Trop Med Parasitol. 1993 Jun;44(2):113-5.
Strategies for detection and control of onchocerciasis in Africa have included identification of DNA probes and PCR target sequences for sensitive and specific detection of parasites. To evaluate the applicability of published PCR and DNA probe based methods for the study of onchocerciasis in Sudan, we collected adult O. volvulus from geographically distinct regions of Sudan (700 miles apart), Abu Hamed (northern desert) and Raja (southwestern savannah), and we examined the similarities between Sudanese O. volvulus repeats and published versions of the repeat from West African O. volvulus. Amplification of DNA extracted from the Raja O. volvulus strain predictably generated a ladder of products, multiples of the base 150 bp repeat, as has been reported from West Africa. However, amplification of DNA from the Abu Hamed O. volvulus isolate resulted in a series of doublets. The unexpected DNA fragments thus amplified differed in size from the base 150 bp unit by approximately 50 base pairs and was most clearly visualized at 150-200 base pairs. DNA sequence analysis of the amplified repeats in the isolate of O. volvulus from Abu Hamed revealed a variant of the 150 bp tandem repeat which contained an extra 49 bp. The additional 49 bp contained two short repeats of 21 bp and 10 bp, corresponding to bases 99-119 and 128-137 respectively, of the known 150 bp O. volvulus repeat. This work demonstrates a variant of the O. volvulus 150 bp tandem repeat, which easily distinguishes Raja and Abu Hamed isolates of O. volvulus, and which has potential value for differentiating Abu Hamed strains of O. volvulus from other strains in East Africa.
非洲盘尾丝虫病的检测与控制策略包括鉴定用于灵敏且特异检测寄生虫的DNA探针和PCR靶序列。为评估已发表的基于PCR和DNA探针的方法在苏丹盘尾丝虫病研究中的适用性，我们从苏丹地理上相距700英里的不同区域（北部沙漠的阿布哈迈德和西南部草原的拉贾）收集了成年旋盘尾丝虫，并研究了苏丹旋盘尾丝虫重复序列与已发表的西非旋盘尾丝虫重复序列版本之间的相似性。正如从西非报道的那样，从拉贾旋盘尾丝虫菌株中提取的DNA扩增可预见地产生了一系列产物条带，即150 bp重复序列的倍数。然而，从阿布哈迈德旋盘尾丝虫分离株中提取的DNA扩增产生了一系列双峰。如此扩增出的意外DNA片段大小与150 bp基本单位相差约50个碱基对，在150 - 200个碱基对处最清晰可见。对来自阿布哈迈德的旋盘尾丝虫分离株中扩增的重复序列进行DNA序列分析，发现了150 bp串联重复序列的一个变体，其中包含额外的49 bp。额外的49 bp包含两个分别为21 bp和10 bp的短重复序列，分别对应于已知的150 bp旋盘尾丝虫重复序列的第99 - 119位和128 - 137位碱基。这项工作证明了旋盘尾丝虫150 bp串联重复序列的一个变体，它能轻易区分拉贾和阿布哈迈德的旋盘尾丝虫分离株，并且对于区分阿布哈迈德的旋盘尾丝虫菌株与东非其他菌株具有潜在价值。
