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Mosquito microRNA Essential for Metabolism and Reproduction, NIAID Grantees Find

In a new study, NIAID-funded scientists at the University of California, Riverside, found that reducing levels of a single small RNA, miR-275, in the mosquito Aedes aegypti can stop important metabolic and reproductive functions. A. aegypti mosquitoes transmit the dengue and Chikungunya viruses, so the new findings could have the potential for disrupting the mosquito’s ability to cause human disease. The study was published in December 2010 in the Proceedings of the National Academy of Sciences.

The mosquito’s genome contains thousands of small, noncoding RNA strands, which affect the production of proteins that regulate development, cell growth and reproduction. MicroRNAs, a type of small RNA that is usually 20-25 base pairs long, operate by binding to messenger RNA and disrupting their translation into protein products.

photo of a mosquito
In this study, A. aegypti mosquitoes were depleted of the microRNA miR-275 and then fed blood. One day later, the mosquito had an expanded abdomen due to disrupted blood digestion, as seen above.
photo of a mosquito digestive system.
The isolated digestive system is shown above.

Smaller Mosquito Population Leads to Less Disease Transmission

We found that microRNA plays a critical role in the regulatory vital functions of the mosquito as a vector,” said study author Alexander Raikhel, Ph.D. The functions regulated by miR-275 include blood digestion, fluid excretion and egg development. Although these life cycle steps take place after the mosquito bites a human or animal, disrupting these parts of the mosquito life cycle would reduce disease transmission in the next generation of mosquitoes by reducing survival and reproduction. If the total number of mosquitoes goes down, fewer infected mosquitoes would bite humans, and transmission of disease would also drop.

The importance of miR-275 could be leveraged in disease control efforts. For example, introducing a gene disruptor that reduces levels of miR-275 in the mosquito population could be used to inhibit transmission of dengue and Chikungunya to people. Since the mosquito life cycle lasts only about 6-8 weeks, with just 1-2 weeks in the adult stage, a successful effort to reduce the mosquito population would make a difference quickly.

The researchers are currently working on creating a transgenic mosquito with lower levels of miR-275. Other future directions include studying the gene targets of miR-275 to understand how they interact, and expanding the search to additional microRNAs that affect other stages of the mosquito life cycle.

References:

Bryant B, Macdonald W, Raikhel AS. (2010). microRNA miR-275 is indispensable for blood digestion and egg development in the mosquito Aedes aegypti. Proc Natl Acad Sci.107(52):22381-22383 (2010).

In This Issue: Disrupting the life cycle of dengue mosquitoes. Proc Natl Acad Sci. 107(52):22361-22362.

Last Updated December 21, 2011

Last Reviewed January 20, 2011