Viriyakosol S, Siripoon N, Petcharapirat C, Petcharapirat P, Jarra W, Thaithong S, Brown K N, Snounou G
Division of Parasitology, National Institute for Medical Research, London, England.
Bull World Health Organ. 1995;73(1):85-95.
The epidemiology of malaria results from the interactions of three gene pools--parasite, human, and mosquito vector--with one another and with their environment. Methods are being developed for characterizing the genetics of human populations at risk and of potential vectors. The characterization of natural populations of Plasmodium and knowledge of their distribution within the human and insect hosts in any given area under study would also greatly enhance understanding of the epidemiology, pathology and biology of this parasite, particularly when combined with simultaneous human and vector studies. This paper describes a polymerase chain reaction (PCR)-based assay which provides a sensitive, reproducible and practical method by which parasite populations within species can be characterized. In order to illustrate the suitability of the PCR assay, four polymorphic domains on the genes of three P. falciparum proteins (MSP1 blocks 2 and 4, MSP2, and GLURP) and one largely conserved region (MSP1 block 17) were chosen for amplification by PCR. DNA derived from 15 in-vitro cultured lines of P. falciparum (7 of which were cloned) and from blood samples obtained from infected patients in Thailand were used as templates for PCR amplification. The amplification products were analysed by gel electrophoresis for length polymorphisms. Seven allelic variants of GLURP, five of MSP1 block 2, three of MSP1 block 4, and nine of MSP2 were detected. This high degree of polymorphism can be used to characterize the genetic composition of any parasite population, at a given time. The paper discusses the applicability of this type of genotyping to epidemiology and urges the adoption of international standards for its use so that data from different areas and different times can be compared.
疟疾的流行病学源于三个基因库（寄生虫、人类和蚊媒）彼此之间以及与它们所处环境的相互作用。目前正在开发一些方法来描述高危人群和潜在病媒的遗传学特征。对疟原虫自然种群的特征描述以及了解它们在任何特定研究区域内人类和昆虫宿主中的分布情况，也将极大地增进对这种寄生虫的流行病学、病理学和生物学的理解，尤其是当与同时进行的人类和病媒研究相结合时。本文描述了一种基于聚合酶链反应（PCR）的检测方法，该方法提供了一种灵敏、可重复且实用的方法，通过此方法可以对物种内的寄生虫种群进行特征描述。为了说明PCR检测方法的适用性，选择了恶性疟原虫三种蛋白质（MSP1第2和4区、MSP2和GLURP）基因上的四个多态性区域以及一个基本保守区域（MSP1第17区）进行PCR扩增。来自15个恶性疟原虫体外培养株系（其中7个是克隆株）以及从泰国感染患者血液样本中提取的DNA用作PCR扩增的模板。通过凝胶电泳分析扩增产物的长度多态性。检测到GLURP的7个等位基因变体、MSP1第2区的5个、MSP1第4区的3个以及MSP2的9个。这种高度的多态性可用于在特定时间描述任何寄生虫种群的遗传组成。本文讨论了这种基因分型方法在流行病学中的适用性，并敦促采用国际标准来使用该方法，以便能够比较来自不同地区和不同时间的数据。
