ABSTRACT
Infectious diseases that are transmitted by arthropod vectors cause millions of deaths annually. Insect arthropods like mosquitoes, tsetse flies, and ticks are medically important arthropods transmitting pathogens of infectious diseases in sub-Saharan Africa. Several intervention strategies for controlling infectious diseases are based on vector control using insecticide-treated nets, chemical sprays, and medication therapies. Recent approaches are now focusing on transmission-blocking interventions that block the transmission of pathogens from vectors to humans. The midgut is an important organ in the immune system of insects and the most challenging environment for infectious pathogens. Certain genes are differentially expressed in insects’ midgut to produce anti-parasite effector molecules which interfere with the development and transmission of parasites. In addition, the midgut microbiota is a major part of the innate immunity of insects. Anti-parasite effector molecules produced by differential expression of immune-related genes and those produced by several symbiotic microorganisms in the midgut of arthropods contribute to their innate immunity. Some metabolic products of endosymbionts modulate the susceptibility of their insect-host
AU: Please check “insect-host” and “vector-host” throughout the text for clarity. to infection and transmission of infectious pathogens. Genetic manipulation offers strategies for the development of transgenic vectors for disease control. Two novel strategies for genetic manipulation—transgenesis and paratransgenesis—are discussed with examples from mosquitoes, tsetse flies, and ticks. Transgenesis attempts the direct genetic manipulation of the vector’s genome to compromise its vectorial competence. Identifying suitable anti-parasite genes that will not impose fitness cost to the vector is an important step in transgenesis. Paratransgenesis on the other hand is the genetic manipulation of the vector’s microbiota for the delivery of antimicrobial molecules in the vector. Some midgut endosymbionts deliver anti-parasite molecules which interact with parasites and inhibit their development and transmission. This chapter discusses the exploitation of arthropod midgut components for the development of interventions against infectious diseases.
