Remarkable genetic polymorphism among Entamoeba histolytica isolates from a limited geographic area
Remarkable genetic polymorphism among Entamoeba histolytica isolates from a limited geographic area
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DOI：
10.1128/jcm.40.11.4081-4090.2002
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发表时间：
2002-11-01
影响因子：
9.4
通讯作者：
Nozaki, T
中科院分区：
文献类型：
--
作者：
Haghighi, A;Kobayashi, S;Nozaki, T
为了了解溶组织内阿米巴虫株在有限地理区域内以及特定社会人群中的基因多态性，我们研究了不编码蛋白质的DNA区域（位点1 - 2和位点5 - 6）以及几丁质酶基因和富含丝氨酸的溶组织内阿米巴蛋白基因中的核苷酸多态性。对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30株溶组织内阿米巴分离株以及4株参考菌株进行了检测。聚合酶链反应（PCR）显示，包含这些位点的PCR片段在数量和大小上都存在显著的多态性。在日本分离株中，在位点1 - 2以及富含丝氨酸的溶组织内阿米巴蛋白的含重复区域，观察到内部重复单元在长度、类型和数量上的多态性。相比之下，在位点5 - 6处的多态性几乎完全体现在一个16核苷酸单元的重复次数上。几丁质酶的含重复区域在这4个位点中似乎多态性最低，一种主要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比从智障机构居民中获得的分离株表现出更复杂的基因多态性。综合考虑所有4个多态性位点，来自男性同性恋者的19株日本分离株均各不相同。相反，从一个机构的群发感染病例中获得的所有分离株都具有相同的基因型，这表明这些病例是由单一的溶组织内阿米巴虫株引起的。在基因型与同工酶型之间，或者基因型与临床表现（如结肠炎或肝脓肿）之间未发现显著相关性。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4个多态性位点对溶组织内阿米巴分离株进行基因分型可作为鉴别单个分离株的工具。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。
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.