Role of mosquito salivary glands

This review briefly focuses on the role of mosquito salivary glands; and on the biological processes and mechanisms relevant to transmission of malarial parasite (Plasmodium), the causative agent for malaria. A key requirement for transmission of the parasite is an infected blood meal which initiates parasite transmission cycle. The blood feeding is an organized biological mechanism which involves use of anticoagulants that cause severe immune reaction by the host, and minimizing the parasite load for its survival. The malarial parasite in the form of a sporozoite initially produced in the midgut-stage oocyts, travels to the salivary glands of blood-sucking female anopheline mosquito vector with a possible exploitation of specific receptors, if any, by it. During the development of Plasmodium in the mosquito midgut, sporozoites burst out of developing oocysts into the hemocoel (an open circulatory system in the insects) to locate and invade salivary glands prior to transmission to a vertebrate host. It is not only an obligatory step, but also seems to facilitate complete maturation of infection-competent sporozoites. The molecular events, especially recognition mechanisms between the sporozoite and salivary glands are poorly characterized, and a clear understanding is certainly expected to identify novel targets for further studies aimed at interrupting parasite transmission cycle.