Melittin is the main component of Bee Venom and has antibacterial activity against several bacteria. To produce the melittin antimicrobial peptide, we constructed transgenic silkworm that expressed melittin gene under the control BmA3 promoter using piggyBac vector. The use of the 3xP3-driven EGFP cDNA as a marker allowed us to rapidly distinguish transgenic silkworm. Mixtures of the donor vector and helper vector were micro-injected into 300 eggs of bivoltin silkworms, Baegokjam. In total, 131 larvae (G0) were hatched and allowed to develop into moths. The resulting G1 generation consisted of 36 broods, and we selected 4 broods containing at least 1 EGFP-positive embryo. The rate of successful transgenesis for the G1 broods was 11%. We identified 12 EGFP-positive G1 moths and these were backcrossed with wild-type moths. With the aim of identifying a melittin as antimicrobial peptide, we investigated the Radical diffusion Assay (RDA) and then demonstrated that melittin possesses high antibacterial activities against gramnegative bacteria.

Insects have been used by humans as food and traditional medicines for many years. Their antimicrobial and anti‐inflammatory activities are a main focus of medicinal insect research. In a previous study, hemocyte extracts prepared from Bombyx mori larvae were found to have anti‐inflammatory effects. Therefore, we injected Lactobacillus cell wall extracts dorsolaterally into the hemocoel to increase antimicrobial peptides produced by silkworm larva. The best overall antimicrobial activities were observed against E. coli after injection of 10 μL hemolymph from immune‐challenged larvae, although the tested extract did not affect the cell proliferation rate. The effects of the immune‐challenged B. mori hemolymph on anti‐inflammatory pathways were determined using reverse transcription quantitative polymerase chain reaction and western blotting to assess the expression of pro‐inflammatory molecules in macrophage‐like human monocytic leukemia THP‐1 cells following treatment with phorbol myristate acetate. The results demonstrated that the hemolymph of immune‐challenged silkworms had antibacterial and anti‐inflammatory effects. The effects of silkworms with immune‐challenged hemolymph could facilitate the development of new types of functional foods, feed additives, and biomaterials with antibacterial and anti‐inflammatory properties.