Characterization of the immune induced antimicrobial peptide in Drosophila melanogaster and Drosophila ananassae

Abstract

Insects can recognize invading pathogens and initiate an immune response. Among them, Drosophila has emerged as an invertebrate model for investigating innate immune responses in which antimicrobial peptides play a crucial role. In the present study, immune-induced antimicrobial peptides were characterized in D. melanogaster and D. ananassae using the agar well diffusion method, HPLC, SDS-PAGE and LC-MS/MS after infection with either S. aureus or E. coli. The HPLC revealed two and three differentially induced components, respectively, in D. melanogaster and D. ananassae fl ies infected with S. aureus and E. coli. The tricine SDS-PAGE analysis also revealed two and fi ve differentially induced proteins, respectively, in D. melanogaster and D. ananassae infected with E. coli. In E. coli infected fl ies, the ~6 kDa band was produced at higher level. Based on LCMS/MS and Mascot analysis, the peptide was identifi ed as a putative cecropin A-like peptide, and the data suggested that both species of Drosophila have exhibited a clear immune response. The fl ies were also able to discriminate between bacteria, as this putative cecropin A-like peptide was produced in fl ies infected with E. coli but not S. aureus.