Native microbiota shape insect vector competence for human pathogens

Abstract

The resident microbiota of insect vectors can impede transmission of human pathogens. Recent studies have highlighted the capacity of endogenous bacteria to decrease viral and parasitic infections in mosquito and tsetse fly vectors by activating their immune responses or directly inhibiting pathogen development. These microbes may prove effective agents for manipulating the vector competence of malaria and other important human pathogens.

Figure 1

The microbiota harbored in the digestive tract of arthropods impacts the ability of vector-borne pathogens to infect the vector. (1) Commensal and symbiotic bacteria associated with the arthropod gut stimulate an antibacterial immune response that also negatively impacts pathogen development. (2) A cross-linked protein layer that inhibits over-activation of the immune system may also protect pathogens in the gut (Kumar et al., 2010). (3) Bacterial populations expand rapidly in the gut following blood ingestion and may provide a physical barrier to pathogen interaction with the gut epithelium. (4) Molecules secreted by bacteria, such as reactive oxygen intermediates or secondary metabolites, may kill or interfere with parasites in the gut before infection of the vector occurs (Cirimotich et al., 2011).