Location: Foreign Arthropod Borne Animal Disease Research
Project Number: 3022-32000-025-034-S
Project Type: Non-Assistance Cooperative Agreement
Start Date: Aug 1, 2026
End Date: Jul 31, 2029
Objective:
This project will evaluate factors that govern the competency of mosquito vectors to transmit and maintain virus circulation in nature.
Objective 1: Compare innate immune gene activation in Aedes and Culex mosquitoes infected with RVFV or JEV.
Objective 2: Investigate the expression of potential virus entry receptors important for vertical transmission of RVFV and JEV.
Approach:
Objective 1 approach: Japanese encephalitis virus (JEV) and Rift Valley fever virus (RVFV) are two high priority mosquito-borne viruses at risk of introduction to the United States. Understanding what factors govern the competency of mosquito vectors to transmit and maintain virus circulation in nature is of utmost importance. The cooperator previously developed an immune gene array that measures the expression of 23 immune genes across all four major immune pathways in the several different mosquito species. This array will be used to provide novel insight into the mechanism of vector competence of major mosquito vectors found in the United States to foreign animal diseases, with an emphasis on JEV or RVFV. Briefly, up to 3 different endemic mosquito species will be infected with JEV or RVFV. At different times post infection, key tissues (midgut, ovaries, and salivary glands) will be dissected and the expression of the different immune genes will be examined. Once targets are identified, the expression of the gene of interest will be knock down to determine if the gene plays an important role in vector competence for the virus.
Objective 2 approach: Maintenance of arboviruses in nature can occur in part by vertical transmission (from female adult to egg) in the mosquito vector. The role of vertical transmission of JEV is much less characterized. The mechanisms by which virus traffics to the reproductive system of the female mosquito has not been characterized for either JEV or RVFV. Mosquitoes will be infected with RVFV or JEV. Following infection, the expression of two mosquitoe receptors will be examined using PCR-based methods. In addtion microscopy will be used to visualize the distribution and expression of both receptors in infected mosquitoes.