Unraveling the Role of Antimicrobial Peptides in Insects

Abstract

Antimicrobial peptides (AMPs) are short, mainly positively charged, amphipathic molecules. AMPs are important effectors of the immune response in insects with a broad spectrum of antibacterial, antifungal, and antiparasitic activity. In addition to these well-known roles, AMPs exhibit many other, often unobvious, functions in the host. They support insects in the elimination of viral infections. AMPs participate in the regulation of brain-controlled processes, e.g., sleep and non-associative learning. By influencing neuronal health, communication, and activity, they can affect the functioning of the insect nervous system. Expansion of the AMP repertoire and loss of their specificity is connected with the aging process and lifespan of insects. Moreover, AMPs take part in maintaining gut homeostasis, regulating the number of endosymbionts as well as reducing the number of foreign microbiota. In turn, the presence of AMPs in insect venom prevents the spread of infection in social insects, where the prey may be a source of pathogens.

Cereal Weevil’s Antimicrobial Peptides: At the Crosstalk between Development, Endosymbiosis and Immune Response

“…AMPs generally consist of twelve to fifty amino acids, with the hydrophobic part of the molecule generally covering more than 50% of amino acids residues. AMPs are divided into subgroups based on their amino acid composition and structure (7,41) . Based on these features, sixteen sequences matching four different categories of AMPs were identified in S. oryzae by combining automated genome annotations and manual curations ( Figure 2; Supplementary table 1 ).…”

“…AMPs are produced by a wild variety of organisms ranging from bacteria to humans (1,2) . AMPs can act additively, synergistically or with high specificity against viral, bacterial, fungal and protozoan pathogens (1,3–7) . These small cationic peptides were shown to target microbial phospholipid membranes, leading to depolarisation, changes in their permeability, and subsequent microbial cell death.…”

“…These small cationic peptides were shown to target microbial phospholipid membranes, leading to depolarisation, changes in their permeability, and subsequent microbial cell death. Some AMPs can also inhibit viral proliferation by disruption of the viral protein synthesis and the viral gene expression (1,7,8) . Although prokaryotic AMPs, called Bacteriocins, have also been described (2) , we will focus here on eukaryotic AMPs.…”

“…Cecropin was reported as a novel bactericidal agent able to permeabilise the membrane of a limited number of Gram-positive bacteria, without affecting eukaryotic cells (9) . Since the discovery of this first AMP, a large number of AMPs have been identified in diverse insect families as an important part of the immune response (7) . Interestingly, recent availability of functional analyses is currently uncovering the level of specificity and synergy of these immune effectors (5,10,11) .…”

Cereal weevils' antimicrobial peptides: at the crosstalk between development, endosymbiosis and immune response

“…AMPs are produced by a wide variety of organisms ranging from bacteria to humans [1,2]. AMPs can act additively, synergistically or with high specificity against viral, bacterial, fungal and protozoan pathogens [1,[3][4][5][6][7]. These small cationic peptides were shown to target microbial phospholipid membranes, leading to depolarization, changes in their permeability and subsequent microbial cell death.…”