Nucleic Acids as Therapeutic Agents - icaam

Fig. 11.7 Schematic representation of the reverse transcription of retroviralRNA (red) to produce ds DNA (minus strand is light blue and plus strand isdark blue). Step 1, a tRNA primes synthesis of the minus strand. RNA showsU3 and U5 elements and polypurine tract (PPT). Step 2, a complete RNA-DNAduplex is formed. Step 3, RNase H digests the vRNA in the RNA-DNA duplexinto small pieces. Step 4, ds DNA copy of the vRNA which can exist as aprovirus integrated into a cell’s DNA. To block the formation of the minusstrand and hence the synthesis of a ds DNA version of the virus, an antisenseoligonucleotide that hybridizes to the PPT region is added. This protectsagainst retroviruses in mice.