Immunization with LJM11 salivary protein protects against infection with Leishmania braziliensis in the presence of Lutzomyia longipalpis saliva

Mice were immunized with LJM11 recombinant salivary protein and challenged with L. braziliensis plus either SGS from Lu. longipalpis (Lbraz+Lulo) or Lu. intermedia (Lbraz+Linter), suggesting that LJM11-induced protection is specific to Lu. longipalpis sand flies supporting the importance of evaluating specificity of salivary-mediated protective responses. [Display omitted] •LJM11 is an immunogenic salivary molecule from Lu. longipalpis that confers protection against L. major infection.•LJM11-immunized mice controlled L. braziliensis infection when coinoculated with Lu. longipalpis SGS.•LJM11-immunized mice infected with L. braziliensis coinoculated with Lu. intermedia SGS did not control infection.•The results suggest that LJM11-induced protection against L. braziliensis infection could be vector species-specific. Leishmania is transmitted in the presence of sand fly saliva. Protective immunity generated by saliva has encouraged identification of a vector salivary-based vaccine. Previous studies have shown that immunization with LJM11, a salivary protein from Lutzomyia longipalpis, is able to induce a Th1 immune response and protect mice against bites of Leishmania major-infected Lutzomyia longipalpis. Here, we further investigate if immunization with LJM11 recombinant protein is able to confer cross-protection against infection with Leishmania braziliensis associated with salivary gland sonicate (SGS) from Lutzomyia intermedia or Lu. longipalpis. Mice immunized with LJM11 protein exhibited an increased production of anti-LJM11 IgG, IgG1 and IgG2a and a DTH response characterized by an inflammatory infiltrate with the presence of CD4+ IFN-γ+ T cells. LJM11-immunized mice were intradermally infected in the ear with L. braziliensis in the presence of Lu. longipalpis or Lu. intermedia SGS. A significant reduction of parasite numbers in the ear and lymph node in the group challenged with L. braziliensis plus Lu. longipalpis SGS was observed, but not when the challenge was performed with L. braziliensis plus Lu. intermedia SGS. A higher specific production of IFN-γ and absence of IL-10 by lymph node cells were only observed in LJM11 immunized mice after infection. After two weeks, a similar frequency of CD4+ IFN-γ+ T cells was detected in LJM11 and BSA groups challenged with L. braziliensis plus Lu. longipalpis SGS, suggesting that early events possibly triggered by immunization are essential for protection against Leishmania infection. Our findings support th