Induction of protective CD4+ T cell-mediated immunity by a Leishmania peptide delivered in recombinant influenza viruses

PLoS One. 2012;7(3):e33161. doi: 10.1371/journal.pone.0033161. Epub 2012 Mar 21.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antigens, Protozoan / chemistry
  • Antigens, Protozoan / genetics*
  • Antigens, Protozoan / immunology
  • CD4-Positive T-Lymphocytes / immunology*
  • CD4-Positive T-Lymphocytes / metabolism
  • Cytokines / metabolism
  • Genetic Vectors / metabolism
  • Immunity, Cellular / immunology
  • Influenza A Virus, H1N1 Subtype / genetics
  • Influenza A Virus, H3N2 Subtype / genetics
  • Interferon-gamma / metabolism
  • Leishmania / immunology*
  • Leishmania / metabolism
  • Leishmaniasis / prevention & control*
  • Leishmaniasis Vaccines / administration & dosage*
  • Leishmaniasis Vaccines / immunology*
  • Mice
  • Mice, Inbred BALB C
  • Muramidase / genetics
  • Protozoan Proteins / chemistry
  • Protozoan Proteins / genetics*
  • Protozoan Proteins / immunology
  • Vaccination
  • Vaccines, DNA / immunology

Substances

  • Antigens, Protozoan
  • Cytokines
  • Leishmaniasis Vaccines
  • Protozoan Proteins
  • Vaccines, DNA
  • LACK antigen, Leishmania
  • Interferon-gamma
  • Muramidase