Alinaghizade Atefe, Mirjalali Hamed, Mohebali Mehdi, Stensvold Christen Rune, Rezaeian Mostafa
Department of Medical Parasitology and Mycology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran.
Foodborne and Waterborne Diseases Research Center, Research Institute for Gastroenterology and Liver Diseases, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
Infect Genet Evol. 2017 Jun;50:77-82. doi: 10.1016/j.meegid.2017.02.016. Epub 2017 Feb 24.
Blastocystis is a common intestinal parasitic protist infecting birds and mammals. Blastocystis comprises at least 17 subtypes (ST), of which ST1-ST9 have been detected in humans. Significant correlation between certain subtypes and pathogenicity remains to be established. Nevertheless, some studies suggest a potential linkage between subtypes (inter- and intra-subtype variation) and clinical manifestations. The aim of this study was to identify intra-subtype genetic variation of subtypes of Blastocystis in stools samples submitted by diarrheic and non-diarrheic patients. A 550-bp fragment of the nuclear small subunit ribosomal rRNA gene was amplified from 58 culture-positive samples isolated from diarrheic and non-diarrheic Iranian patients. PCR products were sequenced and sequences subjected to phylogenetic analysis. Intra-and inter-subtype variation was calculated. Based on comparison with reference sequences in GenBank, ST1, ST2 and ST3 were found in 18 (31.03%), 21 (36.22%), and 19 (32.75%) of the samples, respectively. Diarrheic stools were observed in eight (44.44%), 10 (47.61%), and nine (47.36%) patients with ST1, ST2, and ST3, respectively. No statistically significant correlation was found between subtypes and diarrhea (P=1.000). Multiple sequence alignment exhibited a within-subtype similarity of 98.76%, 97.17%, and 99.78% in ST1, ST2, and ST3, respectively. Highest similarity was seen among ST3 isolates, while lowest similarity was seen among ST2 isolates. Phylogenetic analysis did not suggest any correlation between diarrhea and intra-subtype variation. Inter- and intra-subtype variation in SSU rRNA gene appears not to reflect differences in the clinical outcome of Blastocystis carriage.
芽囊原虫是一种常见的肠道寄生原生生物，可感染鸟类和哺乳动物。芽囊原虫至少包括17个亚型（ST），其中ST1-ST9已在人类中检测到。某些亚型与致病性之间的显著相关性仍有待确定。然而，一些研究表明亚型（亚型间和亚型内变异）与临床表现之间存在潜在联系。本研究的目的是鉴定腹泻和非腹泻患者提交的粪便样本中芽囊原虫亚型的亚型内遗传变异。从58份从伊朗腹泻和非腹泻患者中分离出的培养阳性样本中扩增出核小亚基核糖体rRNA基因的550bp片段。对PCR产物进行测序，并对序列进行系统发育分析。计算亚型内和亚型间变异。基于与GenBank中参考序列的比较，分别在18份（31.03%）、21份（36.22%）和19份（32.75%）样本中发现了ST1、ST2和ST3。ST1、ST2和ST3患者中分别有8例（44.44%）、10例（47.61%）和9例（47.36%）出现腹泻粪便。未发现亚型与腹泻之间存在统计学显著相关性（P=1.000）。多序列比对显示，ST1、ST2和ST3的亚型内相似性分别为98.76%、97.17%和99.78%。ST3分离株之间的相似性最高，而ST2分离株之间的相似性最低。系统发育分析未表明腹泻与亚型内变异之间存在任何相关性。SSU rRNA基因的亚型间和亚型内变异似乎不能反映芽囊原虫携带的临床结果差异。
