title: The role of MHC haplotypes H2d/H2b in mouse resistance/susceptibility to cyst formation is influenced by the lineage of infective Toxoplasma gondii strain.
abstract: Toxoplasma gondii strains displaying the Type I/III genotype are associated with acquired ocular toxoplasmosis in humans. Here, we used a mice model to characterize some immunological mechanisms involved in host resistance to infection with such strains. We have chosen the Type I/III strains D8, G2 and P-Br, which cause a chronic infection in mice that resembles human toxoplamosis. Mice deficient of molecules MyD88, IFN-gamma, and IL-12 were susceptible to all three parasite strains. This finding indicates the importance of innate mechanisms in controlling infection. On the other hand, MHC haplotype did not influenced resistance/susceptibility; since mice lineages displaying a same genetic background but different MHC haplotypes (H2b or H2d) developed similar mortality and cyst numbers after infection with those strains. In contrast, the C57BL/6 genetic background, and not MHC haplotype, was critical for development of intestinal inflammation caused by any of the studied strains. Finally, regarding effector mechanisms, we observed that B and CD8+ T lymphocytes controlled survival,whereas the inducible nitric oxide synthase influenced cyst numbers in brains of mice infected with Type I/III strains. These findings are relevant to further understanding of the immunologic mechanisms involved in host protection and pathogenesis during infection with T. gondii.
authors.affiliation: Laboratório de Imunopatologia, Instituto René Rachou, Belo Horizonte, MG, Brazil.
authors.forename: Marianne G
authors.initials: MG
authors.lastname: Resende
authors.forename: Blima
authors.initials: B
authors.lastname: Fux
authors.forename: Brália C
authors.initials: BC
authors.lastname: Caetano
authors.forename: Erica A
authors.initials: EA
authors.lastname: Mendes
authors.forename: Neide M
authors.initials: NM
authors.lastname: Silva
authors.forename: Adriana M
authors.initials: AM
authors.lastname: Ferreira
authors.forename: Maria Norma
authors.initials: MN
authors.lastname: Melo
authors.forename: Ricardo W A
authors.initials: RW
authors.lastname: Vitor
authors.forename: Ricardo T
authors.initials: RT
authors.lastname: Gazzinelli
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D005838:Genotype; D006239:Haplotypes / Q000235:genetics*; D007371:Interferon-gamma / Q000172:deficiency / Q000276:immunology; D018664:Interleukin-12 / Q000172:deficiency / Q000276:immunology; D008285:Major Histocompatibility Complex / Q000235:genetics* / Q000276:immunology; D051379:Mice; D008815:Mice, Inbred Strains / Q000235:genetics / Q000276:immunology*; D053594:Myeloid Differentiation Factor 88 / Q000172:deficiency / Q000276:immunology; D013997:Time Factors; D051193:Toll-Like Receptors / Q000276:immunology; D014122:Toxoplasma / Q000235:genetics* / Q000472:pathogenicity; D014124:Toxoplasmosis, Animal / Q000276:immunology* / Q000469:parasitology / Q000473:pathology; D016781:Toxoplasmosis, Cerebral / Q000276:immunology* / Q000469:parasitology / Q000473:pathology; D014774:Virulence / Q000235:genetics
chemical_list: D053594:Myeloid Differentiation Factor 88; D051193:Toll-Like Receptors; D018664:Interleukin-12; D007371:Interferon-gamma