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Infect Genet Evol. 2017 Jun;50:77-82. doi: 10.1016/j.meegid.2017.02.016. Epub 2017 Feb 24.

Inter- and intra-subtype variation of Blastocystis subtypes isolated from diarrheic and non-diarrheic patients in Iran.

Author information

1
Department of Medical Parasitology and Mycology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran.
2
Foodborne and Waterborne Diseases Research Center, Research Institute for Gastroenterology and Liver Diseases, Shahid Beheshti University of Medical Sciences, Tehran, Iran. Electronic address: hamed_mirjalali@hotmail.com.
3
Laboratory of Parasitology, Department of Bacteria, Parasites & Fungi, Statens Serum Institut, Copenhagen, Denmark.
4
Department of Medical Parasitology and Mycology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran. Electronic address: rezaiian@tums.ac.ir.

Abstract

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.

KEYWORDS:

Blastocystis; Diarrhea; Iran; Phylogenetic analysis; Subtyping

PMID:
28238960
DOI:
10.1016/j.meegid.2017.02.016
[Indexed for MEDLINE]

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