Isolation, identification and molecular characterization of immune defense proteins from Bacillus thuringiensis challenged Spodoptera litura (Lepidoptera: Noctuidae) larvae

Immune defense proteins mainly contribute to insect humoral immune response against microbial infection. In this study, we identified immune-related proteins which appeared in larval hemolymph of Spodoptera litura after Bacillus thuringiensis bacterial challenge. SDS-PAGE result shows high expression of immune defense protein present in the treated sample. Arylphorin, ecdysone receptor and apolipophorin- III was top score immune proteins when subjected to MALDI-TOF/MS analysis. The docking result shows the interaction of bacterial cell membrane protein (lipopolysaccharide) with the above-isolated proteins. The best rank-sum score observed in arylphorin, GOAP Score; -120978.47, DFIRE Score; - 92961.59, IT Score is; -47803.45. The best interaction defined by binding position, hydrophobicity, ionization of protein, binding surface and hydrogen bonding of complex was observed in arylphorin. The simultaneous presence of protein in immune hemolymph suggests it as a part of a protein involved in fighting against infection in S. litura.