tRNA fragments in the mosquito midgut linked to disease transmission

In a recent study, published in PLoS Neglected Tropical Diseases, Susanta Behura from the University of Missouri (MO, USA) and colleagues investigated the abundance of tRNA fragments (tRFs) in the Aedes aegypti mosquito.

Small RNA molecules such as microRNA and small interfering RNA have been proven to play roles in vector mosquitoes; however, the involvement of tRFs, a newly discovered type of small RNA, had not been elucidated thus far.

To investigate the role of tRFs in vector biology the researchers profiled the expression of tRFs in different Ae. aegypti samples that varied in sex, strain, developmental stage and exposure to dengue virus, blood or antibiotics.

Researchers identified a total of 55 tRFs that are expressed in Ae. aegypti, each originating from a unique tRNA molecule, with the most abundant tRF deriving from precursor sequences of tRNA-Gly.

Bioinformatics analyses demonstrated that specific tRFs displayed differential expression profiles between males and female mosquitoes, during development stages and post blood feeding responses.

Three tRFs also had altered expression levels after treatment with antibiotics, suggesting these may have a role in the gut microbiome and vector competence to dengue virus infection.

The findings suggest that expression of tRFs in an infected mosquito can modulate its ability to transmit viral diseases to humans.

“The results of our current study support the report on emerging roles of tRFs to viral infections,” the researchers concluded: “tRFs are active in this mosquito and may play diverse roles in disease vector biology.”

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Sources: Eng MW, Clemons A, Hill C, Engel R, Severson DW, Behura SK. Multifaceted functional implications of an endogenously expressed tRNA fragment in the vector mosquito Aedes aegypti. PLoS Negl. Trop. Dis. 12(1), e0006186 (2018);


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