Arthropod Innate Immune Systems and Vector-Borne Diseases

Abstract

Arthropods, especially ticks and mosquitoes, are the vectors for a number of parasitic and viral human diseases, including malaria, sleeping sickness, Dengue, and Zika, yet arthropods show tremendous individual variation in their capacity to transmit disease. A key factor in this capacity is the group of genetically encoded immune factors that counteract infection by the pathogen. Arthropod-specific pattern recognition receptors and protease cascades detect and respond to infection. Proteins such as antimicrobial peptides, thioester-containing proteins, and transglutaminases effect responses such as lysis, phagocytosis, melanization, and agglutination. Effector responses are initiated by damage signals such as reactive oxygen species signaling from epithelial cells and recognized by cell surface receptors on hemocytes. Antiviral immunity is primarily mediated by siRNA pathways but coupled with interferon-like signaling, antimicrobial peptides, and thioester-containing proteins. Molecular mechanisms of immunity are closely linked to related traits of longevity and fertility, and arthropods have the capacity for innate immunological memory. Advances in understanding vector immunity can be leveraged to develop novel control strategies for reducing the rate of transmission of both ancient and emerging threats to global health.

Tick-Pathogen Interactions and Vector Competence: Identification of Molecular Drivers for Tick-Borne Diseases

“…Nevertheless, recent results support that in some cases the protein function described in model insect species may be different in the evolutionarily distant ticks. Differences in vector competence may be genetically encoded by differences in the immune response pathways operating at each vector-pathogen interaction (Baxter et al, 2017). For example, Tudor-SN, a conserved component of the basic RNAi machinery with a variety of functions including immune response and gene regulation, is involved in defense against infection in Drosophila (Sabin et al, 2013) but not in ticks (Ayllón et al, 2015b).…”

Antiviral Immune Response and the Route of Infection in Drosophila melanogaster

“…In addition, some insects pose an increasing menace to human and animal health. Insects such as mosquitoes, lice, fleas and bed bugs are able to transmit a number of disease-causing pathogens such as viruses, bacteria, protozoa and nematodes (Baxter et al, 2017). Over one million people worldwide die from mosquito-borne diseases every year.…”

Effect of the CDC light trap on control of nocturnal mosquitoes in coastal Samut Songkhram Province, Thailand

“…At least 412 species of mosquitoes are found in Thailand (Pengsakul et al 2017), including 3 genera that are medically important nocturnal vectors: Anopheles, a malaria vector; Culex, a Japanese encephalitis, and filariasis vector; and Mansonia, a filariasis vector (Baxter et al 2017). In 2017, the Bureau of Epidemiology, Thailand reported 5273 malaria cases, 14 Japanese encephalitis cases and 4 filariasis cases (Ministry of Public Health 2017).…”