ABSTRACT
Infections with Leishmania (L.) major induce protective IFN-γ-dependent Th1/Tc1 immunity in C57BL/6 mice as well as in immunocompetent humans. Even though antigen-specific immunity provides lifelong immunity against reinfection, a vaccine against this pathogen does not yet exist. Here, we compared the results obtained from in silico predictions of murine CD8-specific L. major peptides using the algorithm SYFPEITHI with the number and predicted affinity of known proteins/peptides. Our results indicate that the majority of "immunodominant" epitopes of L. major have not been identified so far; thus, computer-based prediction algorithms may aid the development of an effective vaccine.
Subject(s)
Epitopes, T-Lymphocyte , Leishmania major/immunology , Leishmaniasis, Cutaneous/immunology , Animals , Computer Simulation , Mice, Inbred C57BLSubject(s)
CD8-Positive T-Lymphocytes/immunology , CD8-Positive T-Lymphocytes/pathology , Leishmania major/immunology , Proteasome Endopeptidase Complex/immunology , Animals , CD8-Positive T-Lymphocytes/drug effects , Coculture Techniques , Disease Models, Animal , Interferon-gamma/pharmacology , Langerhans Cells/drug effects , Langerhans Cells/immunology , Langerhans Cells/pathology , Leishmaniasis, Cutaneous/immunology , Leishmaniasis, Cutaneous/pathology , Mice , Mice, Inbred C57BL , Mice, Knockout , Proteasome Endopeptidase Complex/deficiency , Proteasome Endopeptidase Complex/genetics , Skin/immunology , Skin/parasitology , Skin/pathologyABSTRACT
In murine leishmaniasis, healing is mediated by IFN-γ-producing CD4(+) and CD8(+) T cells. Thus, an efficacious vaccine should induce Th1 and Tc1 cells. Dendritic cells (DCs) pulsed with exogenous proteins primarily induce strong CD4-dependent immunity; induction of CD8 responses has proven to be difficult. We evaluated the immunogenicity of fusion proteins comprising the protein transduction domain of HIV-1 TAT and the Leishmania antigen LACK (Leishmania homolog of receptors for activated C kinase), as TAT-fusion proteins facilitate major histocompatibility complex class I-dependent antigen presentation. In vitro, TAT-LACK-pulsed DCs induced stronger proliferation of Leishmania-specific CD8(+) T cells compared with DCs incubated with LACK alone. Vaccination with TAT-LACK-pulsed DCs or fusion proteins plus adjuvant in vivo significantly improved disease outcome in Leishmania major-infected mice and was superior to vaccination with DCs treated with LACK alone. Vaccination with DC+TAT-LACK resulted in stronger proliferation of CD8(+) T cells when compared with immunization with DC+LACK. Upon depletion of CD4(+) or CD8(+) T cells, TAT-LACK-mediated protection was lost. TAT-LACK-pulsed IL-12p40-deficient DCs did not promote protection in vivo. In summary, these data show that TAT-fusion proteins are superior in activating Leishmania-specific Tc1 cells when compared with antigen alone and suggest that IL-12-dependent preferential induction of antigen-specific CD8(+) cells promotes significant protection against this important human pathogen.
