Antisense Nucleotides

Antisense DNA strands can also be made (note that in the double helix, the side of the DNA that is transcribed is itself antisense). Short antisense strands of DNA can be introduced into cells, which then bind with target mRNA. Antisense DNA is currently an approved therapy for cytomegalovirus infections of the eye, under the trade name Vitravene. Vitravene targets two different viral proteins. Antisense DNA is also being explored for therapy of HIV, some cancers, and other diseases.

One advantage of using antisense therapy in treating infectious diseases such as virus infections is that it can be tailored to the particular strain in circulation, and then modified as the virus mutates. One difficulty in applying this therapy is successfully delivering the antisense DNA or RNA to all target tissues (for instance, making sure the antisense strands reach infected blood cells for HIV). Another problem is maintaining prolonged suppression of target protein expression, since the antisense molecule will eventually be degraded by the cell's nuclease enzymes. One strategy to prevent degradation is to chemically modify the DNA to interfere with nuclease action.