title: Molecular phylogenies of Blastocystis isolates from different hosts: implications for genetic diversity, identification of species, and zoonosis.
abstract: Small-subunit (SSU) rRNA gene sequences were obtained by PCR from 12 Blastocystis isolates from humans, rats, and reptiles for which elongation factor 1alpha (EF-1alpha) gene sequences are already available. These new sequences were analyzed by the Bayesian method in a broad phylogeny including, for the first time, all Blastocystis sequences available in the databases. Phylogenetic trees identified seven well-resolved groups plus several discrete lineages that could represent newly defined clades. Comparative analysis of SSU rRNA- and EF-1alpha-based trees obtained by maximum-likelihood methods from a restricted sampling (13 isolates) revealed overall agreement between the two phylogenies. In spite of their morphological similarity, sequence divergence among Blastocystis isolates reflected considerable genetic diversity that could be correlated with the existence of potentially >/=12 different species within the genus. Based on this analysis and previous PCR-based genotype classification data, six of these major groups might consist of Blastocystis isolates from both humans and other animal hosts, confirming the low host specificity of Blastocystis. Our results also strongly suggest the existence of numerous zoonotic isolates with frequent animal-to-human and human-to-animal transmissions and of a large potential reservoir in animals for infections in humans.
authors.affiliation: Unité Inserm U547, Institut Pasteur, 1 Rue du Professeur Calmette, BP 245, 59019 Lille Cedex, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Noël
authors.forename: Fabienne
authors.initials: F
authors.lastname: Dufernez
authors.forename: Delphine
authors.initials: D
authors.lastname: Gerbod
authors.forename: Virginia P
authors.initials: VP
authors.lastname: Edgcomb
authors.forename: Pilar
authors.initials: P
authors.lastname: Delgado-Viscogliosi
authors.forename: Lip-Chuen
authors.initials: LC
authors.lastname: Ho
authors.forename: Mulkit
authors.initials: M
authors.lastname: Singh
authors.forename: René
authors.initials: R
authors.lastname: Wintjens
authors.forename: Mitchell L
authors.initials: ML
authors.lastname: Sogin
authors.forename: Monique
authors.initials: M
authors.lastname: Capron
authors.forename: Raymond
authors.initials: R
authors.lastname: Pierce
authors.forename: Lionel
authors.initials: L
authors.lastname: Zenner
authors.forename: Eric
authors.initials: E
authors.lastname: Viscogliosi
mesh_terms: D000818:Animals; D016844:Blastocystis / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification; D016776:Blastocystis Infections / Q000469:parasitology*; D016054:DNA, Protozoan / Q000032:analysis; D004275:DNA, Ribosomal / Q000032:analysis; D020459:Genes, rRNA / Q000235:genetics; D014644:Genetic Variation; D006790:Host-Parasite Interactions; D006801:Humans; D008969:Molecular Sequence Data; D020648:Peptide Elongation Factor 1 / Q000235:genetics; D010802:Phylogeny; D011529:Protozoan Infections, Animal / Q000469:parasitology*; D051381:Rats; D012104:Reptiles / Q000469:parasitology; D017422:Sequence Analysis, DNA; D013045:Species Specificity; D015047:Zoonoses / Q000469:parasitology*
chemical_list: D016054:DNA, Protozoan; D004275:DNA, Ribosomal; D020648:Peptide Elongation Factor 1