Novel RNA Interference (RNAi)-Based Nanomedicines for Treating Viral Infections - Harnessing Biomaterials in Nanomedicine: Preparation, Toxicity, and Applications - page 226

7.6 Conclusions
The studies discussed above have definitely cleared apprehensions
about engineering RNAi for the in vivo control of viral infections. As
these technologies continue to advance, the main focus no longer
remains proof-of-principle experimentation in animal models, but
making it a feasible and cost-eff ective treatment option for clinical
application.
The ease and speed of synthesis of siRNAs confers upon them a
higher ground in comparison with the conventional protein, peptide
and antibody therapies. Even with chemical drugs, the complexity
involved in developing a new one for a particular malady is dissuasive
when considering the ease and speed of siRNA design although the
associated costs could be higher with the RNAi therapeutics. RNAi
therapeutics appear to be perfectly suited for controlling fast and
acute viral infections making it a particularly smart choice for
combating epidemics and pandemics like the 2009 H1N1 outbreak
or as a weapon against a bioterror attack. Another niche for these
drugs would be in topical applications like microbicide formulations
for the prevention of sexually transmitted infections where rapid
kinetics of drug action is warranted.
While the use of RNAi for treating chronic ailments is debatable
in the face of viral ability to mutate under shRNA pressure, aiming
at the immutable host factors that viruses rely on seem to be a
good strategy. While the search is on for expandable host targets,
the enormous data gleaned from high-throughput screening for
human factors promoting viral infections like HIV, [13, 67, 127, 133],
Influenza [53, 63], HCV [99] and WNV [68], have revealed a plethora
of targets for investigation.
Finally, another approach to combating viral infections that is
being actively pursued is to attack non-human viral reservoirs using
antiviral RNAi in an eff ort to prevent transmission to the human hosts.
This approach has been explored in the mosquito vector to limit
replication of flaviviruses [17, 39, 111] and has proven efficacious in
laboratory-controlled studies. More recently, this approach is being
examined in the poultry reservoir of influenza by testing siRNAs in
drinking water or in aerosol sprays and also developing chickens
transgenic for antiviral shRNAs [26, 96] . While these alternate avenues
are being explored for RNAi implementation, it appears inevitable
that a RNAi-based drug will hit the market not too far in the future.