In an attempt to overcome the limitations and drawbacks of combinatorial antiretroviral therapy, which is currently used to suppress viral replication in HIV patients, Zhou and colleagues have been investigating safe and effective delivery of therapeutic doses of siRNAs to target tissues.
The researchers previously delivered anti-HIV small interfering RNAs (siRNAs) to cells by covalent conjugation to aptamers. This design required synthesizing a different DNA transcription template for each siRNA–aptamer construct.
In this article, the researchers describe a modification to the aptamer–siRNA molecule that creates an aptamer–bridge construct and improves the utility of aptamers as siRNA delivery vehicles. The aptamer specific to HIV-1 gp120 (anti-gp120 aptamer) was synthesized with a 3’ 7-carbon linker, which was attached to a 16-nt, 2’-O-methyl/2-fluoro, GC-rich bridge sequence. The siRNA, a Dicer-substrate siRNA (DsiRNA), also included a bridge sequence that was the reverse complement of the aptamer bridge. The bridge sequences hybridize providing a means to connect the 2 molecules and to easily interchange distinct DsiRNAs. The researchers describe the use of this construct for effective in vivo delivery of a cocktail of DsiRNAs manufactured by IDT.
The authors further demonstrate functional in vivo delivery of multiplexed DsiRNAs using the aptamer–bridge construct by showing knockdown of target mRNAs and potent inhibition of HIV-1 replication, as well as prolonged complete suppression of HIV-1 viral loads after follow-up treatment.