Salivary gland antigens of laboratory-bred Phlebotomus sergenti and their immunogenicity in human volunteers in laboratory condition

Objective: To investigate Phlebotomus (P.) sergenti Parrot, 1917 (Diptera: Psychodidae) salivary gland antigens and their immune response in human. Methods: Human volunteers were exposed to sand flies' bites in the laboratory, and following each exposure the size of induration was recorded. The mean protein concentration of salivary gland lysate and specific anti-P. sergenti saliva IgG was measured. Sand fly salivary proteins were separated by SDS-PAGE and their immunoreactivity was examined by Western blotting assays. Results: Individuals exposed to P. sergenti salivary gland lysate for 8 months showed both antibody and delayed type hypersensitivity responses, although exposure for one month did not provoke any immune responses. The trend of antibody fluctuated during the exposure time and dropped by the end of antigen loading. The mean protein content was (0.36±0.08) μg in each pair salivary glands. Salivary gland lysate showed 11 to 12 major protein bands and 3 to 6 of them were immunoreactive. Conclusions: Our study showed that the salivary gland components of P. sergenti provoked both cellular and humoral immune responses in human. Furthermore, there are some mmunogenic proteins in P. sergenti saliva which could be subjected for further investigation as vector-based vaccine candidate/s against anthroponotic cutaneous leishmaniasis.