Antimicrobial peptides in insects; structure and function

Molecular characterization of a defensin in the IZD‐MB‐0503 cell line derived from immunocytes of the insect Mamestra brassicae (Lepidoptera)

“…Our data, together with the results from Lamberty et al (1999), seem to confirm that, as reported by Bulet et al (1999), defensins form a family of anti-bacterial peptides that is widely distributed in insects, and Lepidoptera are no exception.…”

The iron–siderophore transporter FhuA is the receptor for the antimicrobial peptide microcin J25: role of the microcin Val11–Pro16 β-hairpin region in the recognition mechanism

“…Unlike most antimicrobial peptides that display low specificity and MIC values in the range 0.1-20 µM associated with a membrane-permeabilizing activity [ [30][31][32], the narrow spectrum of activity and the high potency of MccJ25 are reminiscent of a receptor-mediated mechanism of action. Interestingly, in our antibacterial assays, only four bacterial species belonging to the Escherichia and Salmonella genera, known to express FhuA, were MccJ25-susceptible.…”

Pre-exposure to yeast protects larvae of Galleria mellonella from a subsequent lethal infection by Candida albicans and is mediated by the increased expression of antimicrobial peptides

“…The humoral element of the immune response consists of proteins involved in clotting such as vitellogenin-like proteins that contain a cysteinerich region which is homologous to the mammalian clottable proteins of the Von Willebrand factor involved in blood clotting [2], and antimicrobial peptides (AMPs) such as defensins, which have been highly conserved through evolution [4]. AMPs are released from a range of organs and cells [5,6] into the haemolymph of the insect where they diffuse to the site of infection and attack components of the bacterial or fungal cell wall [7]. Haemocytes, the fat body and the digestive tract secrete antimicrobial proteins and peptides into the insect haemolymph, which performs many functions analogous to mammalian serum [5,6,8].…”

“…AMPs are released from a range of organs and cells [5,6] into the haemolymph of the insect where they diffuse to the site of infection and attack components of the bacterial or fungal cell wall [7]. Haemocytes, the fat body and the digestive tract secrete antimicrobial proteins and peptides into the insect haemolymph, which performs many functions analogous to mammalian serum [5,6,8]. The similarity of a range of insect immune responses with vertebrate innate immune responses to infection has been highlighted by the discovery of the Toll receptors in insects and their similarity with the toll like receptors (TLR) in mammals and 11 members of this family have been identified in humans [9].…”