Background & objectives: Salivary gland proteins play a pivotal role in blood feeding, epithelial interactions, and parasite transmission in mosquito vectors. Anopheles culicifacies is a complex of five sibling species, viz. A, B, C, D, and E, with diverse geographical distribution patterns. Among these, sibling species B has been identified as poor vector. Exploring the differentially expressed salivary proteins in An. culicifacies may potentially identify refractoriness factors during malaria parasite maturation and may help to elucidate the mechanism of refractoriness.
Methods: A comparative proteomic analysis was carried out using tandem mass tag (TMT) technology combined with LC-MS/MS mass spectrometry and bioinformatics analysis, to identify the differentially expressed salivary gland proteins among An. culicifacies species A (susceptible) and An. culicifacies species B (refractory) mosquitoes.
Results: A total of 82 proteins were found to be differentially expressed. Out of these, seven proteins including TRIO, translation initiation factor 5C, glutathione S-transferase, and 5' nucleotidase were up-regulated, and 75 proteins including calreticulin, elongation factors, fructose biphosphatase, isocitrate dehydrogenase, histone proteins and anti-platelet proteins, etc. were down-regulated in refractory species. Analysis of KEGG pathways showed that the up-regulated proteins were related to fatty acid metabolism and RNA transport pathways.
Interpretation & conclusion: This comparative proteomic analysis of susceptible and refractory An. culicifacies salivary gland proteins identifies the plausible role of the differential proteome in immune responses, digestion, energy, and carbon metabolic pathways. This information may serve as a basis for future work concerning the possible role of these proteins in refractoriness dependent metabolic function of mosquitoes.
Keywords: Anopheles culicifacies; mass spectrometry; proteomics; refractory; salivary gland; tandem mass tag (TMT).