Identification of microRNAs expressed in the midgut of Aedes albopictus during dengue infection

Background: the midgut is the first barrier to dengue virus (denv) infections of mosquitoes and therefore is a major bottleneck for the subsequent development of vector competence. however,the molecular mechanisms responsible for this barrier are unknown. results: we constructed three small rna libraries from the midguts of adult aedes albopictus females that had been fed on either sugar solution,an uninfected blood meal,or a blood meal infected with denv-2,and112 conserved micrornas represented by 173 mirna sequences were identified,with 34 novel micrornas predicted by mireap,rnafold and sfold software. in addition,the expression of aal-mir-1174,aal-mir-2951 and aal-mir-956 was confirmed via stem-loop quantitative real-time pcr (qrt-pcr). compared with microrna expression profiles of mosquitoes that had ingested a regular blood meal,43 micrornas were upregulated and 4were downregulated in mosquitoes that had ingested a denv-2-infected blood meal. among the differentially expressed micrornas,mir-1767,mir-276-3p,mir-4448 and mir-4728-5p were verified via stem-loop qrt-pcr. conclusions: analyses indicated that the changing patterns in mirna expression during denv-2 infection were significant and varied at different time points post infection. most mirna were upregulated at 24 h but were downregulated at 48 h post denv-2 intake. the aal-mir-4728-5p was chosen for an in vitro transient transfection assay,and the results show that this mirna enhances denv replication in c6/36 cells. this study provides the first information on micrornas expressed in the midgut of ae. albopictus and describes species-specific changes in their expression levels following infection by denv-2. © 2017 the author(s).