Proteomic and Transcriptomic Analyses of Salivary Glands of Anophesles campestris-like Mosquito, a Potential Vector of Plasmodium vivax

Abstract

Malaria sporozoites must invade the salivary glands of mosquito vectors before transmitting to vertebrate hosts. The sporogonic cycle span within the mosquitoes ranges from 10 to 21 days depending on the species of parasites and temperature. Salivary proteins of the mosquitoes are injected into the vertebrate host during blood feeding, together with malaria sporozoites. Anopheles campestris-like is a high-potential malaria vector of Plasmodium vivax in Thailand. In this study, its salivary gland proteins were determined and analyzed. Also, the salivary gland proteins depleted after blood feeding were identified and quantified by using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), two-dimentional gel electrophoresis (2-DE) and nano-liquid chromatography-mass spectrometry (Naono-LC/MS). The total amount of salivary gland proteins in the three to five days old male and female mosquitoes were approximately 0.1 ± 0.05 µg/gland pair and 1.38 ± 0.01 µg/gland pair, respectively. SDS-PAGE analysis revealed at least 12 major proteins in the female salivary glands. The major proteins expressed in each morphological region of the female glands were different. In addition, at least 14 glycoproteins were detected in the salivary glands of the females. Interestingly, salivary gland protein profiles of the male mosquitoes were similar to the proximal-lateral lobes of female glands, suggesting that a role of these lobes involves sugar feeding. 2-DE analysis showed that 19 major protein spots depleted significantly in the female salivary glands of three to five days old mosquitoes when fed on their first blood meal, and 14 major proteins decreased significantly in mosquitoes fed on their second blood meal at days 14 after the first blood meal. The significantly depleted proteins in both groups included putative 5’-nucleotidase/apyrase, anti-platelet protein, long-form D7 salivary gland protein, D7-related 1 protein, short form D7r1 and gSG6. Moreover, abundant cDNA clones were isolated from a female An. campestris-like salivary gland cDNA library constructed in this study. BLAST analysis revealed that two in 30 cDNA clones were matched significantly with D7-related 1 Anopheles stephensi at 66 % and 74 %, respectively. This result suggests that the D7-related 1 protein is expressed abundantly in the salivary glands of female An. campestris-like mosquitoes.