Role of the Vector in Arbovirus Transmission

Abstract

Many arboviral diseases are uncontrolled, and the viruses that cause them are globally emerging or reemerging pathogens that produce significant disease throughout the world. The increased spread and prevalence of disease are occurring during a period of substantial scientific growth in the vector-borne disease research community. This growth has been supported by advances in genomics and proteomics, and by the ability to genetically alter disease vectors. For the first time, researchers are elucidating the molecular details of vector host-seeking behavior, the susceptibility of disease vectors to arboviruses, the immunological control of infection in disease vectors, and the determinants that facilitate transmission of arboviruses from a vector to a host. These discoveries are facilitating the development of novel strategies to combat arboviral disease, including the release of transgenic mosquitoes harboring dominant lethal genes, the introduction of arbovirus-blocking microbes into mosquito populations, and the development of acquisition- and transmission-blocking therapeutics. Understanding the role of the vector in arbovirus transmission has provided critical practical and theoretical tools to control arboviral disease.

Keywords: host; immune response; mosquito; saliva protein.

Figure 1

Model of saliva-mediated infectivity enhancement. ❶ Infected mosquitoes inoculate virus-laden saliva mostly into host dermal tissue during probing for a blood meal. ❷ Saliva serine proteases break down dermal extracellular matrix, which modulates the immune response. ❸ Langerhans cell migration is induced, which increases the probability of interaction with immobilized virions. ❹ Infected Langerhans cells migrate to draining lymph nodes, thereby enhancing the dissemination of virus into the host.

Figure 2

Available (black) and theoretical (red) interventions to combat arboviral disease. Physical barriers, pesticides, repellants, and attractants/traps are the only methods available to prevent arboviral diseases. Supportive care is the only treatment option available in most cases. The development of a traditional vaccine for dengue virus has been problematic due to antibody-dependent enhancement. New research has paved the way for vector-based interventions including acquisition- and transmission-blocking vaccines and therapeutics, biological control agents, and the release of genetically altered, sterile mosquitoes.