title: Immunodepression induced by Trypanosoma cruzi and mouse hepatitis virus type 3 is associated with thymus apoptosis.
abstract: Trypanosoma cruzi-infected mice show disturbance in the peripheral immune system such as polyclonal lymphocyte activation, autoantibody production, and immunosuppression of T lymphocytes. Previous observations in our laboratory showed that some stocks of T. cruzi can be contaminated with mouse hepatitis virus type 3 (MHV-3). Literature has shown that MHV-3 infection induces immunologic disorders characterized by thymic involution with marked cell depletion. However, the effects of interactions between MHV-3 and the parasite on the immune system are not well understood. In the present study specific-pathogen-free CBA mice were inoculated with MHV-3, alone or associated with different stocks of T. cruzi. Concurrent murine virus infection resulted in increased pathogenicity of T. cruzi infection shown by profound thymic atrophy; loss of cortical thymocytes; depletion of Thy1.2+, CD4+, and CD8+ cells; enhancement of in situ labeling of nuclear DNA fragmentation; and eventually, death of the animals. Such lines of evidence show that the mechanism underlying this thymic atrophy is associated with apoptosis. These results also suggest that MHV-3 can account for the increased immunosuppression observed during experimental infection with the parasite.
authors.affiliation: Department of Microbiology and Immunology, UNICAMP, Campinas, São Paulo, Brazil.
authors.forename: L
authors.initials: L
authors.lastname: Verinaud
authors.forename: M A
authors.initials: MA
authors.lastname: Da Cruz-Höfling
authors.forename: J K
authors.initials: JK
authors.lastname: Sakurada
authors.forename: H A
authors.initials: HA
authors.lastname: Rangel
authors.forename: J
authors.initials: J
authors.lastname: Vassallo
authors.forename: D
authors.initials: D
authors.lastname: Wakelin
authors.forename: H F
authors.initials: HF
authors.lastname: Sewell
authors.forename: I J
authors.initials: IJ
authors.lastname: Camargo
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000276:immunology*; D001323:Autoantibodies / Q000276:immunology; D014355:Chagas Disease / Q000276:immunology*; D006524:Hepatitis, Viral, Animal / Q000276:immunology*; D007165:Immunosuppression Therapy; D051379:Mice; D008808:Mice, Inbred CBA; D006517:Murine hepatitis virus / Q000276:immunology*; D013950:Thymus Gland / Q000276:immunology* / Q000473:pathology; D014349:Trypanosoma cruzi / Q000276:immunology*
chemical_list: D001323:Autoantibodies