Adenovirus type 5 vectors encoding short hairpin RNAs targeting dengue virus 5’ non-translated region and capsid gene suppress pre-established dengue infection in cultured epithelial and myeloid cells

Abstract

Dengue, a mosquito-borne viral disease, caused by any of four serotypes of dengue viruses (DENV-1, -2, -3 and -4), is estimated to affect >1 million of the world's population daily. We showed earlier that a recombinant human adenovirus type 5 (HuAd5) vector, encoding a short hairpin RNA (shRNA), targeting a conserved sequence in the DENV genome, could effectively suppress pre-established DENV-2 infection in Vero cells. In this study, we identified an additional conserved shRNA target in the DENV genome, developed a HuAd5 vector to target this site, and evaluated if HuAd5-delivered shRNAs suppress pre-established infection by the remaining three DENV serotypes, not only in Vero cells, but also in macrophages, the in vivo sites of DENV replication in infected individuals. We also assessed the effect of anti-HuAd5 antibodies on shRNA delivery.We show that recombinant HuAd5 vectors, encoding shRNAs targeting conserved DENV genomic sequences, in the 5’ non-translated region and capsid gene, can suppress ongoing replication of all four prototypic DENV serotypes in Vero cells and in a HuAd5-refractory human macrophage cell line expressing a DENV attachment factor. DENV suppression was assessed on the basis of inhibition of viral antigen secretion, viral RNA replication and progeny virus generation. Interestingly, HuAd5 vector-mediated DENV suppression in the macrophage cell line was dependent on the presence of anti-HuAd5 antibody. This suggests that HuAd5 vector complexed to its antibody enters these cells through the Fc receptor pathway. This may have implications for specific targeting of HuAd5 vector-mediated antiviral RNA interference therapy to macrophages.