title: Inter- and intra-subtype variation of Blastocystis subtypes isolated from diarrheic and non-diarrheic patients in Iran.
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.
authors.affiliation: Department of Medical Parasitology and Mycology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Atefe
authors.initials: A
authors.lastname: Alinaghizade
authors.affiliation: 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.
authors.forename: Hamed
authors.initials: H
authors.lastname: Mirjalali
authors.affiliation: Department of Medical Parasitology and Mycology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Mehdi
authors.initials: M
authors.lastname: Mohebali
authors.affiliation: Laboratory of Parasitology, Department of Bacteria, Parasites & Fungi, Statens Serum Institut, Copenhagen, Denmark.
authors.forename: Christen Rune
authors.initials: CR
authors.lastname: Stensvold
authors.affiliation: Department of Medical Parasitology and Mycology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran. Electronic address: rezaiian@tums.ac.ir.
authors.forename: Mostafa
authors.initials: M
authors.lastname: Rezaeian
mesh_terms: D000818:Animals; D001483:Base Sequence; D016844:Blastocystis / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification; D016776:Blastocystis Infections / Q000453:epidemiology* / Q000469:parasitology; D002417:Cattle; D003967:Diarrhea / Q000453:epidemiology* / Q000469:parasitology; D005243:Feces / Q000469:parasitology; D005260:Female; D014644:Genetic Variation; D005838:Genotype; D006801:Humans; D007492:Iran / Q000453:epidemiology; D008297:Male; D010802:Phylogeny; D012337:RNA, Ribosomal, 18S / Q000235:genetics*; D016415:Sequence Alignment
chemical_list: D012337:RNA, Ribosomal, 18S
keywords: Blastocystis; Diarrhea; Iran; Phylogenetic analysis; Subtyping