title: Induction of protective CD4+ T cell-mediated immunity by a Leishmania peptide delivered in recombinant influenza viruses.
abstract: The available evidence suggests that protective immunity to Leishmania is achieved by priming the CD4(+) Th1 response. Therefore, we utilised a reverse genetics strategy to generate influenza A viruses to deliver an immunogenic Leishmania peptide. The single, immunodominant Leishmania-specific LACK(158-173) CD4(+) peptide was engineered into the neuraminidase stalk of H1N1 and H3N2 influenza A viruses. These recombinant viruses were used to vaccinate susceptible BALB/c mice to determine whether the resultant LACK(158-173)-specific CD4(+) T cell responses protected against live L. major infection. We show that vaccination with influenza-LACK(158-173) triggers LACK(158-173)-specific Th1-biased CD4(+) T cell responses within an appropriate cytokine milieu (IFN-γ, IL-12), essential for the magnitude and quality of the Th1 response. A single intraperitoneal exposure (non-replicative route of immunisation) to recombinant influenza delivers immunogenic peptides, leading to a marked reduction (2-4 log) in parasite burden, albeit without reduction in lesion size. This correlated with increased numbers of IFN-γ-producing CD4(+) T cells in vaccinated mice compared to controls. Importantly, the subsequent prime-boost approach with a serologically distinct strain of influenza (H1N1->H3N2) expressing LACK(158-173) led to a marked reduction in both lesion size and parasite burdens in vaccination trials. This protection correlated with high levels of IFN-γ producing cells in the spleen, which were maintained for 6 weeks post-challenge indicating the longevity of this protective effector response. Thus, these experiments show that Leishmania-derived peptides delivered in the context of recombinant influenza viruses are immunogenic in vivo, and warrant investigation of similar vaccine strategies to generate parasite-specific immunity.
authors.affiliation: Department of Microbiology and Immunology, The University of Melbourne, Parkville, Victoria, Australia. kkedz@unimelb.edu.au
authors.forename: Katherine
authors.initials: K
authors.lastname: Kedzierska
authors.forename: Joan M
authors.initials: JM
authors.lastname: Curtis
authors.forename: Sophie A
authors.initials: SA
authors.lastname: Valkenburg
authors.forename: Lauren A
authors.initials: LA
authors.lastname: Hatton
authors.forename: Hiu
authors.initials: H
authors.lastname: Kiu
authors.forename: Peter C
authors.initials: PC
authors.lastname: Doherty
authors.forename: Lukasz
authors.initials: L
authors.lastname: Kedzierski
mesh_terms: D000818:Animals; D000953:Antigens, Protozoan / Q000737:chemistry / Q000235:genetics* / Q000276:immunology; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D016207:Cytokines / Q000378:metabolism; D005822:Genetic Vectors / Q000378:metabolism; D007111:Immunity, Cellular / Q000276:immunology; D053118:Influenza A Virus, H1N1 Subtype / Q000235:genetics; D053122:Influenza A Virus, H3N2 Subtype / Q000235:genetics; D007371:Interferon-gamma / Q000378:metabolism; D007891:Leishmania / Q000276:immunology* / Q000378:metabolism; D007896:Leishmaniasis / Q000517:prevention & control*; D054332:Leishmaniasis Vaccines / Q000008:administration & dosage* / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D009113:Muramidase / Q000235:genetics; D015800:Protozoan Proteins / Q000737:chemistry / Q000235:genetics* / Q000276:immunology; D014611:Vaccination; D019444:Vaccines, DNA / Q000276:immunology
chemical_list: D000953:Antigens, Protozoan; D016207:Cytokines; D054332:Leishmaniasis Vaccines; D015800:Protozoan Proteins; D019444:Vaccines, DNA; C093139:LACK antigen, Leishmania; D007371:Interferon-gamma; D009113:Muramidase