title: PATHOGENICITY OF Blastocystis sp. TO THE GASTROINTESTINAL TRACT OF MICE: RELATIONSHIP BETWEEN INOCULUM SIZE AND PERIOD OF INFECTION.
abstract: The pathogenic potential of Blastocystis sp. in experimental models requires further investigation. In this work, the pathogenicity of this parasite in the gastrointestinal tract of male Swiss mice was evaluated according to the inoculum size and period of infection. Animals were infected intragastrically, with 100, 500, 1,000, 5,000 and 10,000 Blastocystis sp. vacuolar forms obtained from a mixture of eight human isolates cultured axenically in Jones' medium. After seven, 14, 21, 28 and 60 days of infection, the animals were sacrificed and fragments of the small intestine (duodenum), large intestine, and cecum were subjected to histopathological analysis. Blastocystis sp. triggered an inflammatory response in the different tissues analyzed, with a predominance of mononuclear cells. The parasite was found in the muscular layer of the cecum, showing its invasive character. Larger inocula triggered inflammatory processes earlier (seven days) than smaller ones (from 21 days). We conclude that, in the proposed model, the pathogenicity of Blastocystis sp. isolates that were studied is related to inoculum size and period of infection.
authors.affiliation: Universidade Estadual de Maringá, Campo Mourão, Paraná, Brasil.
authors.forename: Mariana F
authors.initials: MF
authors.lastname: Pavanelli
authors.affiliation: Universidade Estadual de Maringá, Maringá, PR, Brasil.
authors.forename: Edilson Nobuyoshi
authors.initials: EN
authors.lastname: Kaneshima
authors.affiliation: Universidade Estadual de Maringá, Maringá, PR, Brasil.
authors.forename: Carla F
authors.initials: CF
authors.lastname: Uda
authors.affiliation: Universidade Estadual de Maringá, Maringá, PR, Brasil.
authors.forename: Cristiane M
authors.initials: CM
authors.lastname: Colli
authors.affiliation: Universidade Estadual de Maringá, Maringá, PR, Brasil.
authors.forename: Ana L
authors.initials: AL
authors.lastname: Falavigna-Guilherm
authors.affiliation: Universidade Estadual de Maringá, Maringá, PR, Brasil.
authors.forename: Mônica L
authors.initials: ML
authors.lastname: Gomes
mesh_terms: D000818:Animals; D016844:Blastocystis / Q000472:pathogenicity*; D016776:Blastocystis Infections / Q000503:physiopathology*; D002432:Cecum / Q000469:parasitology; D004386:Duodenum / Q000469:parasitology; D005243:Feces / Q000469:parasitology; D041981:Gastrointestinal Tract / Q000469:parasitology*; D006801:Humans; D007420:Intestine, Large / Q000469:parasitology; D007963:Leukocytes, Mononuclear / Q000469:parasitology; D008297:Male; D051379:Mice; D059208:Parasite Load; D013997:Time Factors