Haghighi Ali, Kobayashi Seiki, Takeuchi Tsutomu, Masuda Gohta, Nozaki Tomoyoshi
Department of Parasitology, National Institute of Infectious Diseases, Shinjuku-ku. Department of Tropical Medicine and Parasitology, Keio University School of Medicine, Shinjuku-ku. Tokyo Metropolitan Kiyose Children's Hospital, Kiyose-shi, Tokyo, Japan.
J Clin Microbiol. 2002 Nov;40(11):4081-90. doi: 10.1128/JCM.40.11.4081-4090.2002.
In order to understand genetic polymorphisms among Entamoeba histolytica strains in a limited geographic area and among restricted social populations, we studied nucleotide polymorphism in DNA regions that do not encode proteins (locus 1-2 and locus 5-6) and in genes coding for chitinase and for serine-rich E. histolytica protein. Thirty E. histolytica isolates from domestically infected Japanese amebiasis patients (male homosexuals and residents in institutions for the mentally handicapped) and four reference strains were examined. PCR revealed remarkable polymorphisms in both the number and size of the PCR fragments containing these loci. Polymorphisms in lengths, types, and numbers of internal repeat units were observed in locus 1-2 and the repeat-containing region of serine-rich E. histolytica protein among the Japanese isolates. In contrast, polymorphism at locus 5-6 was observed almost exclusively in the number of repeats of a 16-nucleotide unit. The repeat-containing region of chitinase appeared to be the least polymorphic among the four loci with a single dominant genotype representing 66% (20 out of 30) of all of the isolates. Isolates obtained from male homosexuals showed a more complex genetic polymorphism than those from residents in institutions. Considering all four polymorphic loci together, all 19 Japanese isolates from male homosexuals were distinct. In contrast, all isolates obtained from mass-infection cases at a single institution had an identical genotype, suggesting that these cases were caused by a single E. histolytica strain. No significant correlation was found between genotypes and zymodemes or between genotypes and clinical presentations, e.g., colitis or liver abscess. Certain genotypes were observed with higher frequencies in male homosexuals or residents of institutions. These data indicate that genotyping of the E. histolytica isolates by using these four polymorphic loci could serve as a tool to fingerprint individual isolates. We propose that genotyping of ameba isolates should help to determine geographic origins of isolates and routes of transmission.
为了解有限地理区域内和特定社会人群中的溶组织内阿米巴菌株的基因多态性，我们研究了非编码蛋白质的DNA区域（基因座1 - 2和基因座5 - 6）以及编码几丁质酶和富含丝氨酸的溶组织内阿米巴蛋白的基因中的核苷酸多态性。检测了30株来自日本国内感染阿米巴病患者（男性同性恋者和智障机构居民）的溶组织内阿米巴分离株以及4株参考菌株。聚合酶链反应（PCR）显示，含有这些基因座的PCR片段在数量和大小上均存在显著多态性。在日本分离株中，基因座1 - 2和富含丝氨酸的溶组织内阿米巴蛋白的含重复序列区域在内部重复单元的长度、类型和数量上存在多态性。相比之下，基因座5 - 6的多态性几乎仅体现在一个16核苷酸单元的重复次数上。几丁质酶的含重复序列区域似乎是四个基因座中多态性最少的，单一优势基因型占所有分离株的66%（30株中的20株）。从男性同性恋者中获得的分离株显示出比从机构居民中获得的分离株更复杂的基因多态性。综合考虑所有四个多态性基因座，来自男性同性恋者的所有19株日本分离株均不同。相比之下，在单个机构的群体感染病例中获得的所有分离株具有相同的基因型，表明这些病例由单一的溶组织内阿米巴菌株引起。未发现基因型与酶谱型之间或基因型与临床表现（如结肠炎或肝脓肿）之间存在显著相关性。某些基因型在男性同性恋者或机构居民中出现的频率较高。这些数据表明，利用这四个多态性基因座对溶组织内阿米巴分离株进行基因分型可作为对个体分离株进行指纹识别的工具。我们提出，对阿米巴分离株进行基因分型应有助于确定分离株的地理来源和传播途径。
