In-silico homology modeling of three isoforms of insect defensins from the dengue vector mosquito, Aedes aegypti (Linn., 1762).

Dengue is a serious public health problem in tropical and subtropical countries. It is caused by any of the four serologically distinct dengue viruses, namely DENV1-4. The viruses are transmitted by Aedes mosquitoes. Understanding various defence mechanisms of insects has become a prime area of research worldwide. In insects, the first line of defence against invading pathogens includes cellular mechanisms and a battery of antimicrobial peptides such as defensins, cecropins etc. Defensins--cationic, cysteine-rich peptides consisting of approximately 40 amino acids with broad-spectrum activity against Gram-positive bacteria--have been reported from a wide range of organisms. In the dengue vector mosquito, Aedes aegypti, three isoforms of defensins are reported to be expressed in a spatial and temporal fashion. This report presents the three-dimensional structures of the three isoforms of Ae. aegypti defensins predicted by comparative modeling. Prediction was done with Modeller 9v1 and the structures validated through a series of tests. The best results of the prediction study are presented, and may help lead to the discovery of new synthetic peptides or derivatives of defensins that could be useful in the control of vector-borne diseases.