MIR-281,an abundant midgut-specific miRNA of the vector mosquito Aedes albopictus enhances dengue virus replication

Background: emerging evidence indicates that micrornas (mirnas) are involved in host-virus interaction. we previously reported that some mirnas were differentially expressed in sugar-fed and blood-fed females of aedes albopictus (ae. albopictus). here,we analysis the role in the host-virus system of an abundant midgut-specific mirna in the mosquito ae. albopictus. methods: the expression profiles of mir-281 in different body parts of ae. albopictus and following dengue virus infection were determined using rt-qpcr and northern blot. mir-281 mimics,antagomirs and corresponding negative controls were designed and their overexpression and knock-down efficiency were analyzed by qrt-pcr after transfecting the mosquito cell lines c6/36,and also by injecting female mosquitoes. dengue virus serotype-2 (denv-2) viral genomic rna abundance was determined by rt-qpcr. the levels of denv-2 e protein were detected using western blot. virus titers were tested using tcid50. rnahybrid was used to predict targets of mir-281 in the denv-2 genome. the egfp plasmid-based reporter system was used to investigate the interaction between mir-281 and the predicted binding site in the c6/36 cell line. results: mir-281 is specifically expressed in the female midgut where dengue virus first invades. after denv-2 infection,this mirna is up-regulated in response to viral infection. functional intervention analyses in vitro with specifically designed mir-281 mimics and corresponding antagomirs indicated that mir-281 enhances denv-2 viral replication. further depletion of mir-281 in female mosquitoes by injection of its specific antagomirs led to a significant reduction in denv-2 abundance. the interaction between mir-281 and its predicted target sequence,the denv-2 genomic 5'-untranslated region (utr),is confirmed in the context of a plasmid-based reporter system. conclusion: these findings confirm that mir-281,an abundant midgut-specific mirna,facilitates denv-2 replication. © 2014 zhou et al.