Combinatorial activities of antimicrobial peptides expressed in medicinal maggots of the blow fly Lucilia sericata against bacteria. Lucilia-RNAseq

The larvae of the common green bottle fly (Lucilia sericata) produce antibacterial secretions that have a therapeutic effect on chronic and non-healing wounds. Recent developments in insect biotechnology have made it possible to use these larvae as a source of novel anti-infectives. Here we report the use of next-generation transcriptome sequencing (RNAseq) to characterize the larval glands, crop and gut, which contribute to the synthesis of antimicrobial peptides and proteins (AMPs) secreted into wounds. Our data confirm that L. sericata larvae have adapted to colonize microbially-contaminated habitats such as carrion and necrotic wounds and are protected against infection by a diverse spectrum of AMPs. L. sericata AMPs include not only lucifensin and lucimycin but also novel attacins, cecropins, diptericins, proline-rich peptides and sarcotoxins. We identified 47 genes encoding putative AMPs, 25 of which were produced as synthetic analogs. These were tested alone or in combination against Escherichia coli (Gram negative) and Micrococcus luteus (Gram positive). We found mostly additive but also synergistic activity when selected AMPs were tested in combination. The AMPs are easy to synthesize and are currently being produced in bulk to allow their evaluation as novel anti-infectives that can be formulated in hydrogels to produce therapeutic wound dressings and adhesive bandages.