The immune response of Drosophila melanogaster

Abstract

The response of the fruit fly Drosophila melanogaster to various microorganism infections relies on a multilayered defense. The epithelia constitute a first and efficient barrier. Innate immunity is activated when microorganisms succeed in entering the body cavity of the fly. Invading microorganisms are killed by the combined action of cellular and humoral processes. They are phagocytosed by specialized blood cells, surrounded by toxic melanin, or lysed by antibacterial peptides secreted into the hemolymph by fat body cells. During the last few years, research has focused on the mechanisms of microbial recognition by various pattern recognition receptors and of the subsequent induction of antimicrobial peptide expression. The cellular arm of the Drosophila innate immune system, which was somehow neglected, now constitutes the new frontier.

Biometrical genetic analysis of luteovirus transmission in the aphid Schizaphis graminum

“…Responses to bacterial, fungal and protozoal pathogens include melanization, phagocytosis and cellular encapsulation by hemocytes, as well as secretion of antimicrobial peptides (Leclerc and Reichhart, 2004;Levashina, 2004;Loker, 2004). However, the response to viral pathogens is considered to be distinct, as Drosophila genes involved in anti-bacterial and antifungal immunity are not induced by virus pathogens (Sabatier et al, 2003;Leclerc and Reichhart, 2004). An encapsulation immune response to a baculovirus was described in Helicoverpa zea (Trudeau et al, 2001).…”

Physical stress primes the immune response of Galleria mellonella larvae to infection by Candida albicans

“…The humoral immune response is mediated by the production of a range of antimicrobial peptides, the formation of melanin or the coagulation of haemolymph to seal ruptures in the cuticle or retard the passage of pathogens. AMPs are released from a range of organs and cells [7,8] into the haemolymph of the insect where they diffuse to the site of infection and attack components of the bacterial or fungal cell wall [9].…”

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].…”