Multifaceted functional implications of an endogenously expressed tRNA fragment in the vector mosquito Aedes aegypti.

The mosquito Aedes aegypti is the primary vector of human arboviral diseases caused by dengue, chikungunya and Zika viruses. Many studies have shown the potential roles of small RNA molecules such as microRNA, small interfering RNA and PIWI-interacting RNA in vector mosquitoes. The function of tRNA fragments (tRF), the newly discovered class of small RNAs, in mosquitoes is not known. In this study, we show that specific tRFs are expressed in significantly differential manner between males and females of Ae. aegypti strains. Specific tRFs also show differential response during developmental transition from larvae to adults, as well as after blood feeding of adult females. The expression pattern of tRFs upon blood feeding varied depending upon if the blood contained dengue virus, and also if the females were treated with antibiotic prior to feeding to cleanse of the gut bacteria. Our findings show that a single tRF derived from the precursor sequences of a tRNA-Gly was differentially expressed between males and females, developmental transitions and also upon blood feeding by females of two laboratory strains that vary in midgut susceptibility to dengue virus infection. The multifaceted functional implications of this specific tRF suggest that biogenesis of small regulatory molecules from a tRNA can have wide ranging effects on key aspects of Ae. aegypti vector biology.