Genus-specific salivary proteins as serological markers of human exposure to mosquito bites

Salivary proteins injected by mosquitoes into hosts play an essential blood feeding role by counteracting hemostasis, inflammation and immunity; however, they also elicit an immune response with production of anti-saliva antibodies. Several experimental observations support the concept that this antibody response to saliva may be exploited to assess human exposure to vectors and, therefore, may represent a helpful tool to evaluate disease risk and efficacy of anti-vector control interventions. In the last years we analyzed the salivary repertoires of Anopheles gambiae, Aedes aegypti and Aedes albopictus and identified genus-specific salivary proteins, i.e. proteins that are found in Anopheles but not in Aedes or Culex saliva, and viceversa. These proteins, if immunogenic, could be ideal markers of exposure to mosquito vectors. Based on this information we have recently shown that the antibody response to the Anopheles-specific salivary protein gSG6 is a promising marker to evaluate human exposure to Afrotropical malaria vectors. The wide spread of the tiger mosquito in Italy/Europe, as well as the recent Chikungunja and Dengue cases in Italy and France, highlighted the need for both effective control interventions and tools to evaluate their efficacy. In this respect the development of recombinant salivary antigens as markers of human exposure to Ae. albopictus could be extremely useful. Such a tool may allow to directly monitor, through simple serological measures, the effect of mosquito control interventions on human exposure to Aedes mosquito bites. To this end we selected seven different Ae. albopictus salivary proteins (which are absent in the saliva of Anopheles and Culex species) and cloned corresponding cDNAs in suitable E. coli expression vectors. Optimization of conditions for their expression and purification is currently in progress.