title: Multilocus sequence typing of Dientamoeba fragilis identified a major clone with widespread geographical distribution.
abstract: The flagellated protozoan Dientamoeba fragilis is often detected in humans with gastrointestinal symptoms, but it is also commonly found in healthy subjects. As for other intestinal protozoa, the hypothesis that genetically dissimilar parasite isolates differ in their ability to cause symptoms has also been raised for D. fragilis. To date, only two D. fragilis genotypes (1 and 2) have been described, of which genotype 1 largely predominates worldwide. However, very few markers are available for genotyping studies and therefore the extent of genetic variation among isolates remains largely unknown. Here, we performed metagenomics experiments on two D. fragilis-positive stool samples, and identified a number of candidate markers based on sequence similarity to the phylogenetically related species Trichomonas vaginalis. Markers corresponding to structural genes and to genes encoding for proteases were selected for this study, and PCR experiments confirmed their belonging to the D. fragilis genome; two previously described markers (small subunit ribosomal DNA and large subunit of RNA polymerase II) were also included. Using this panel of markers, 111 isolates of human origin were genotyped, all of which, except one, belonged to genotype 1. These isolates had been collected at different times from symptomatic and asymptomatic persons of different age groups in Italy, Denmark, Brazil and Australia. By sequencing approximately 160kb from 500 PCR products, a very low level of polymorphism was observed across all the investigated loci, suggesting the existence of a major clone of D. fragilis with a widespread geographical distribution.
authors.affiliation: Istituto Superiore di Sanità, Rome, Italy. Electronic address: simone.caccio@iss.it.
authors.forename: Simone M
authors.initials: SM
authors.lastname: Cacciò
authors.affiliation: Istituto Superiore di Sanità, Rome, Italy.
authors.forename: Anna Rosa
authors.initials: AR
authors.lastname: Sannella
authors.affiliation: Laboratory of Parasitology, Microbiology and Virology, IRCCS San Matteo Hospital Foundation, Pavia, Italy.
authors.forename: Antonella
authors.initials: A
authors.lastname: Bruno
authors.affiliation: Department of Microbiology and Infection Control, Statens Serum Institut, Denmark.
authors.forename: Christen R
authors.initials: CR
authors.lastname: Stensvold
authors.affiliation: Parasitology Department, Institute of Bioscience, São Paulo State University, São Paulo, Brazil.
authors.forename: Erica Boarato
authors.initials: EB
authors.lastname: David
authors.affiliation: Parasitology Department, Institute of Bioscience, São Paulo State University, São Paulo, Brazil.
authors.forename: Semiramis
authors.initials: S
authors.lastname: Guimarães
authors.affiliation: Laboratory of Parasitology, Istituto Zooprofilattico Sperimentale dell'Umbria e delle Marche, Perugia, Italy.
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Manuali
authors.affiliation: Laboratory of Parasitology, Istituto Zooprofilattico Sperimentale dell'Umbria e delle Marche, Perugia, Italy.
authors.forename: Chiara
authors.initials: C
authors.lastname: Magistrali
authors.affiliation: Western Diagnostic Pathology, Myaree, WA, Australia.
authors.forename: Karim
authors.initials: K
authors.lastname: Mahdad
authors.affiliation: Western Diagnostic Pathology, Myaree, WA, Australia.
authors.forename: Miles
authors.initials: M
authors.lastname: Beaman
authors.affiliation: Laboratory of Parasitology, Microbiology and Virology, IRCCS San Matteo Hospital Foundation, Pavia, Italy.
authors.forename: Roberta
authors.initials: R
authors.lastname: Maserati
authors.affiliation: Istituto Superiore di Sanità, Rome, Italy.
authors.forename: Fabio
authors.initials: F
authors.lastname: Tosini
authors.affiliation: Istituto Superiore di Sanità, Rome, Italy.
authors.forename: Edoardo
authors.initials: E
authors.lastname: Pozio
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D004029:Dientamoeba / Q000145:classification* / Q000235:genetics; D004030:Dientamoebiasis / Q000469:parasitology*; D005243:Feces / Q000469:parasitology; D005260:Female; D005819:Genetic Markers; D014644:Genetic Variation; D060005:Genotyping Techniques; D006801:Humans; D008297:Male; D008875:Middle Aged; D058885:Multilocus Sequence Typing; D010447:Peptide Hydrolases / Q000235:genetics; D016133:Polymerase Chain Reaction; D055815:Young Adult
chemical_list: D005819:Genetic Markers; D010447:Peptide Hydrolases
keywords: Dientamoeba fragilis; Genetic markers; Human; Multilocus genotyping; Population structure