Human anti-saliva immune response following experimental exposure to the visceral leishmaniasis vector, Lutzomyia longipalpis

Authors

  • Vera Vinhas,

    1. Centro de Pesquisas Gonçalo Moniz (FIOCRUZ) and Faculdade de Medicina da Bahia, Universidade Federal da Bahia, Bahia, Brazil
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  • Bruno B. Andrade,

    1. Centro de Pesquisas Gonçalo Moniz (FIOCRUZ) and Faculdade de Medicina da Bahia, Universidade Federal da Bahia, Bahia, Brazil
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  • Fábio Paes,

    1. Centro de Pesquisas Gonçalo Moniz (FIOCRUZ) and Faculdade de Medicina da Bahia, Universidade Federal da Bahia, Bahia, Brazil
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  • Andréa Bomura,

    1. Centro de Pesquisas Gonçalo Moniz (FIOCRUZ) and Faculdade de Medicina da Bahia, Universidade Federal da Bahia, Bahia, Brazil
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  • Jorge Clarencio,

    1. Centro de Pesquisas Gonçalo Moniz (FIOCRUZ) and Faculdade de Medicina da Bahia, Universidade Federal da Bahia, Bahia, Brazil
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  • José C. Miranda,

    1. Centro de Pesquisas Gonçalo Moniz (FIOCRUZ) and Faculdade de Medicina da Bahia, Universidade Federal da Bahia, Bahia, Brazil
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  • André Báfica,

    1. Immunobiology Section, Laboratory of Parasitic Diseases, NIAID, National Institutes of Health, Bethesda, USA
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  • Aldina Barral,

    1. Centro de Pesquisas Gonçalo Moniz (FIOCRUZ) and Faculdade de Medicina da Bahia, Universidade Federal da Bahia, Bahia, Brazil
    2. Instituto de Investigação em Imunologia, Instituto do Milênio, Bahia, Brazil
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  • Manoel Barral-Netto Dr.

    Corresponding author
    1. Centro de Pesquisas Gonçalo Moniz (FIOCRUZ) and Faculdade de Medicina da Bahia, Universidade Federal da Bahia, Bahia, Brazil
    2. Instituto de Investigação em Imunologia, Instituto do Milênio, Bahia, Brazil
    • Centro de Pesquisas Gonçalo Moniz (FIOCRUZ), Rua Waldemar Falcão, 121, Candeal, CEP: 40295-001 Salvador–Bahia, Brazil, Fax: +55-71-3176-2279
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Abstract

Experiments in animals verified that phlebotomine saliva enhances Leishmania infection, and vaccination with saliva prevents disease. We have shown that individuals from an endemic area of visceral leishmaniasis displayed robust antibody responses to saliva from the vector Lutzomyialongipalpis, which correlated with anti-parasite cell-mediated immunity. Here, we explored human anti-saliva responses following exposure to sand flies, using an in vivo bite model in which normal volunteers were exposed four times to 30 laboratory-reared Lu. longipalpis. Following the third exposure, normal volunteers developed diverse dermatological reactions at the site of insect bite. Serum from normal volunteers displayed high levels of anti-salivary gland sonicate IgG1, IgG4 and IgE as well as several salivary gland proteins. Furthermore, following in vitro stimulation with salivary gland sonicate, there was an increased frequency of CD4+CD25+ and CD8+CD25+ T cells as well as IFN-γ and IL-10 synthesis. Strikingly, 1 year after the first exposure, PBMC from the volunteers displayed recall IFN-γ responses that correlated with a significant reduction in infection rates using a macrophage-lymphocyte autologous culture. Together, these data suggest that human immunization against sand fly saliva is feasible and recall responses are obtained even 1 year after exposure, opening perspectives for vaccination in man.

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