From transcriptome to immunome: Identification of DTH inducing proteins from a Phlebotomus ariasi salivary gland cDNA library

Delayed-type hypersensitivity (DTH) response to arthropod vector salivary proteins is associated with protection against pathogen transmission. Massive cDNA sequencing, high-throughput DNA plasmid construction and DNA immunisation were used to identify twelve DTH inducing proteins isolated from a Phlebotomus ariasi salivary gland cDNA library. Additionally, nine P. ariasi DNA plasmids produced specific anti-saliva antibodies, four of these showed a Th1 immune response while the other two exhibited a Th2 profile as determined by IgG2a and IgG1 isotype switching, respectively. In order to validate the specificity of sand fly DNA plasmids, mice previously exposed to sand fly saliva were intradermally injected once with selected P. ariasi plasmids and a specific DTH response consisting of infiltration of mononuclear cells in varying proportions was observed at 24 and 48 h. This approach can help to identify DTH inducing proteins that may be related to host protection against vector-borne diseases or other disease agents where cellular immune response is protective.