Cellular and humoral host immune response to sand fly saliva

Sand flies (Diptera: Phlebotominae) are bloodfeeding insects serving as vectors of Leishmania parasites (Kinetoplastida). Sand flies possess salivary glands with pharmacologically active molecules that provide them with an effective weapon against the host defence and that play an important role in Leishmania infection development. During the bloodfeeding, sand fly saliva is inoculated into the feeding site. Repeated exposures induce saliva-specific immune response, both humoral and cell-mediated. While anti-saliva antibody response correlates with the intensity of exposure and can be used as a marker of exposure, specific cellular immunity provide protection against leishmaniasis in some vector-parasite- host combinations. Sand flies differ in composition of the saliva and thus the elicited immunity is species-specific. This species-specific variability makes difficult the development of one saliva-based vaccine applicable to different Leishmania-vector combinations. However, saliva composition is more conserved among closely-related vector species, which may evoke cross-protection in bitten and subsequently infected hosts. We focused on cross-reactive properties of saliva from Phlebotomus papatasi and Phlebotomus duboscqi, the two natural vectors of Leishmania major. We demonstrated that..