Performance of LBSap vaccine after intradermal challenge with L. infantum and saliva of Lu. longipalpis: immunogenicity and parasitological evaluation

PLoS One. 2012;7(11):e49780. doi: 10.1371/journal.pone.0049780. Epub 2012 Nov 26.

Abstract

In the last decade, the search for new vaccines against canine visceral leishmaniasis has intensified. However, the pattern related to immune protection during long periods after experimental infection in vaccine trials is still not fully understood. Herein, we investigated the immunogenicity and parasitological levels after intradermal challenge with Leishmania infantum plus salivary gland extract in dogs immunized with a vaccine composed of L. braziliensis antigens plus saponin as an adjuvant (LBSap vaccine). The LBSap vaccine elicited higher levels of total anti-Leishmania IgG as well as both IgG1 and IgG2. Furthermore, dogs vaccinated had increased levels of lymphocytes, particularly circulating B cells (CD21(+)) and both CD4(+) and CD8(+) T lymphocytes. LBSap also elicited an intense in vitro cell proliferation associated with higher levels of CD4(+) T lymphocytes specific for vaccine soluble antigen and soluble lysate of L. infantum antigen even 885 days after experimental challenge. Furthermore, LBSap vaccinated dogs presented high IFN-γ and low IL-10 and TGF-β1 expression in spleen with significant reduction of parasite load in this tissue. Overall, our results validate the potential of LBSap vaccine to protect against L. infantum experimental infection and strongly support further evaluation of efficiency of LBSap against CVL in natural infection conditions.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adjuvants, Immunologic
  • Animals
  • Antibodies, Protozoan / blood
  • Antibodies, Protozoan / immunology
  • Antigens, CD / metabolism
  • Antigens, Protozoan / immunology
  • B-Lymphocytes / immunology
  • B-Lymphocytes / metabolism
  • Cytokines / immunology
  • Cytokines / metabolism
  • Dog Diseases / immunology
  • Dog Diseases / parasitology
  • Dog Diseases / prevention & control*
  • Dogs
  • Female
  • Histocompatibility Antigens Class II / immunology
  • Histocompatibility Antigens Class II / metabolism
  • Immunity, Humoral
  • Immunoglobulin G / blood
  • Immunoglobulin G / immunology
  • Immunophenotyping
  • Leishmania infantum / genetics
  • Leishmania infantum / immunology*
  • Leishmaniasis Vaccines / immunology*
  • Leishmaniasis, Visceral / veterinary*
  • Lymphocyte Activation / immunology
  • Male
  • Monocytes / immunology
  • Monocytes / metabolism
  • Parasite Load
  • Saponins / immunology
  • T-Lymphocyte Subsets / immunology
  • T-Lymphocyte Subsets / metabolism

Substances

  • Adjuvants, Immunologic
  • Antibodies, Protozoan
  • Antigens, CD
  • Antigens, Protozoan
  • Cytokines
  • Histocompatibility Antigens Class II
  • Immunoglobulin G
  • Leishmaniasis Vaccines
  • Saponins

Grant support

This work was supported by Fundação de Amparo à Pesquisa do Estado de Minas Gerais (FAPEMIG), Universidade Federal de Ouro Preto (UFOP), Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), and Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.