Epidemiological survey and classification of genotypes of intestinal parasitic protozoa Blastocystis

虽然，致病潜力的肠道寄生虫，芽囊原虫hominis，已提出的基础上的临床症状，真正的性质，寄生虫感染的人仍然是有争议的。从B开始。虽然已知人型疟原虫具有遗传多态性，但通常认为寄生虫的某些基因型可能有助于其致病潜力。本研究正是在这样的背景下，开展了人类囊胚感染的调查研究，并确定了囊胚感染人群的基因型。由于日本人囊胚感染的患病率低于其他亚洲发展中国家，因此在泰国、中国和新加坡开展了该项目。最后，从泰国2个不同的流行病学环境中获得了总共47个分离株。在中国，从4个不同的流行病学环境中获得了270株分离株。在新加坡，仅从新加坡的一家大医院获得9株分离株。用我们开发的序列标记位点引物对我国270个分离株进行PCR筛选，除1个分离株外，其余均被归入已知基因型。由于分离株用任何STS引物均为阴性，因此对小亚基rRNA基因的整个序列进行测序，并与已知基因型进行遗传学分析。有趣的是，一个人分离株与GenBank中报道的另外2个分离株被定位在一个额外的新分支中。

Although, pathogenic potential of an intestinal parasite, Blastocystis hominis, had been proposed on the basis of clinical symptom, the true nature of the parasite infection in humans is still controversial. Since B. hominis is known to be genetically polymorphic, it is generally assumed that the certain genotype of the parasite may contribute to its pathogenic potential. Based on these backgrounds, this project was performed on the survey of human Blastocystis infection and determined genotypes among Blastocystis populations. Since the prevalence of human Blastocystis infection in Japan was lower than other developing Asian countries, this project was performed in Thailand, China and Singapore. Finally, a total 47 isolates were obtained from 2 different epidemiological setting in Thailand. In China, 270 isolates were obtained from 4 different epidemiological setting. In Singapore, only 9 isolates were obtained from a major hospital in Singapore. When 270 isolates in China was screened by PCR with our developed sequenced tagged-site primers, all of the isolates except for an isolate were classified into the known genotypes. Since an isolate was negative with any STS primers, entire sequence of the small subunit rRNA gene was sequence and phylogenetically analyzed with the known genotypes. Interestingly, an human isolates was positioned in an additional new clade with other 2 isolates reported in GenBank.