Regulation of Antimicrobial Peptide Genes in Insects by the Toll Pathway and NF-kB Transcription Factors

Abstract

Insects lack adaptive immunity and solely rely on innate immunity to combat pathogens. Innate immunity in dipteran and lepidopteran insects mainly depends on two canonical pathways, the Toll pathway that provides protection against Gram-positive bacteria, fungi and viruses, and the Immune Deficiency (IMD) pathway, which provides protection against Gram-negative bacteria. Insect innate immune responses can be categorized broadly into two types: cellular and humoral. The cellular responses include insect blood cells known as hemocytes that are involved in phagocytosis, nodulation, encapsulation, and wound healing. The humoral immune responses, on the other hand include production of antimicrobial peptides (AMPs) by fat body, which is equivalent to mammalian liver, prophenoloxidase, lectins and compliment-like factors. Chapter 1 talks about the important features of insect innate immunity. Chapter 2 discusses the role of the Toll-7 receptor in Drosophila melanogaster against bacterial and viral infections. Chapter 3 depicts a new constitutively active short relish isoform lacking inhibitory domain in D. melanogaster that functions towards providing protection to low load of infection. Chapter 4 illustrates the role of a transcription factor in Manduca sexta known as Forkhead (MsFkh) that is involved in innate immunity. Lastly, Chapter 5 will summarize all data and foretell future perspectives.