The role of MHC haplotypes H2d/H2b in mouse resistance/susceptibility to cyst formation is influenced by the lineage of infective Toxoplasma gondii strain.
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.
Resende
Marianne G
MG
Laboratório de Imunopatologia, Instituto René Rachou, Belo Horizonte, MG, Brazil.
Fux
Blima
B
Caetano
Brália C
BC
Mendes
Erica A
EA
Silva
Neide M
NM
Ferreira
Adriana M
AM
Melo
Maria Norma
MN
Vitor
Ricardo W A
RW
Gazzinelli
Ricardo T
RT
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
D053594:Myeloid Differentiation Factor 88; D051193:Toll-Like Receptors; D018664:Interleukin-12; D007371:Interferon-gamma