Colorado State University researchers have revealed that dengue-transmitting mosquitoes keep the illness at bay by initiating an immediate and potent immune response. Though mosquitoes commence RNAi right after they ingest blood containing dengue virus, the virus is able to multiply in the mosquitoes anyway, which explains how they are able to pass along the virus to other organisms.
This team previously showed that increasing the RNAi response in mosquitoes prevented dengue infection. In the new study, however, they show that temporarily impairing this immune response increased virus transmission.
The scientists analyzed RNA from adult mosquitoes. They found that both the trigger and initiator molecules for RNAi were formed in mosquitoes after infection, yet viral RNA could readily be detected in the same mosquitoes. They also measured infectious virus rates in the mosquitoes’ saliva, which revealed levels high enough to transmit the disease to humans.
Determining how the virus evades the mosquito’s defense is the next step in keeping the virus from being transmitted.
The study is published online in the February 13 edition of PLoS Pathogens.
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