Keddie E M, Higazi T, Boakye D, Merriweather A, Wooten M C, Unnasch T R
Division of Geographic Medicine, University of Alabama at Birmingham, Birmingham, Alabama, 35294, USA.
Exp Parasitol. 1999 Dec;93(4):198-206. doi: 10.1006/expr.1999.4450.
West African populations of Onchocerca volvulus endemic to the rain forest and savanna bioclimes of West Africa differ in their ability to induce ocular disease in infected individuals. In recent years, both clinical- and animal-model-based studies have implicated particular parasite antigens in the development of ocular onchocerciasis. To test the hypothesis that the difference in pathogenic potential of blinding and nonblinding parasites might be reflected in qualitative differences in antigens that have been implicated in the development of ocular onchocerciasis, we compared the sequences of two parasite antigens implicated in the development of ocular disease in blinding- and nonblinding-strain parasites. The results demonstrated a high level of homogeneity between the parasite strains in these genes. The study was extended to include additional nuclear genes encoding antigens that are commonly recognized by individuals infected with O. volvulus and to the mitochondrial genome of the parasite. The results demonstrate a high degree of homogeneity in both the nuclear and the mitochondrial genomes among O. volvulus isolates collected from several different sites in Africa and in the Americas. This high degree of genetic homogeneity may reflect the passage of the parasite through a recent genetic bottleneck.
西非盘尾丝虫的西非种群分布于西非的雨林和稀树草原生物气候区，它们在感染个体中诱发眼部疾病的能力有所不同。近年来，基于临床和动物模型的研究均表明，特定的寄生虫抗原与盘尾丝虫性眼病的发展有关。为了验证致盲和非致盲寄生虫致病潜力的差异可能体现在与盘尾丝虫性眼病发展相关的抗原的质量差异这一假说，我们比较了致盲和非致盲品系寄生虫中与眼部疾病发展相关的两种寄生虫抗原的序列。结果表明，这些基因在寄生虫品系之间具有高度的同源性。该研究进一步扩展至包括额外的核基因，这些核基因编码的抗原通常为感染盘尾丝虫的个体所识别，同时还扩展至寄生虫的线粒体基因组。结果显示从非洲和美洲的几个不同地点采集的盘尾丝虫分离株在核基因组和线粒体基因组中均具有高度的同源性。这种高度的遗传同源性可能反映了寄生虫最近经历了遗传瓶颈。
