MicroRNA and mosquitos: Possible method for arbovirus restriction?

Contributed by Guest Blogger: C. Romero ’14

Recent research has shown that microRNA miR-275 in the Aedes aegypti mosquito is necessary for blood digestion and egg development. A. aegypti is the most common vector of arboviruses, or ARthropod-BOrne viruses, which include the dengue fever and yellow fever viruses that infect millions and kill thousands each year. Mosquitoes require vertebrate blood to produce eggs, making them good vectors for human diseases. Blood feeding and egg maturation occur in cycles, where blood feeding is required to trigger a step in the process of egg production. In A. aegypti, researchers from University of California, Riverside led by Alexander Raikhel found that miR-275 plays a critical role in this regulatory system.
MicroRNA is a relatively recent discovery, having been first identified in 1993. It appears as if their primary function is post-transcriptional regulation, in which microRNA sequences bind to complementary mRNA. The outcome has come to be known as translational repression or gene silencing, where mRNA is kept from reaching ribosomes and producing proteins, thus interrupting gene expression.
The researchers developed a RNA inhibitor specific to the microRNA molecule, known as an antagomir, to bind to miR-275 before it could silence its corresponding mRNA. By injecting female A. aegypti with this antagomir, blood digestion, fluid excretory function and egg production were all severely inhibited.
This discovery opens new doors to control of the spread of arboviruses, where removal of a single tiny molecule can limit the mosquito’s function at a fundamental level.
Many new questions arise from this research, some of which are already pending investigation by Raikhel’s UC Riverside team. The researchers plan on looking into the particular mRNA that miR-275 targets, and thus find the genes that regulate the blood-meal-mediated egg maturation cycle and see what role they play. Raikhel also plans on looking into the mechanism that underlies the activation of miR-275.
Further off, however, are considerations of how to bring this finding into the real world with a new mosquito control method. New innovations in microRNA research will surely bring us closer to harnessing its power, much as the scientific community has done in DNA genetics.