Fig. 1

Antiviral mechanism of ODN sequences. a Schematic representation of reverse transcription of HIV and mechanism of ODN A action. The HIV-1 extended polypurine tract (PPT) is indicated as black box with the RT/RNase H cleavage side depicted in white. ODN A interacts with the highly conserved PPT, mimicking the natural replication intermediate RNA-DNA hybrid, which results in premature activation of reverse transcriptase (RT)/RNase H hydroloysis of the viral RNA genome. b Sequences of the ODNs used. All ODNs form hairpin-like structures with an antisense (lower) and passenger (upper) strand linked by four thymidines. Watson-Crick bonds are shown as vertical bars. Phosphorothioate-modified nucleotides are shown in bold and marked by a star. The ODN A sequence is complementary to the extended PPT, and ODN Co targets an HIV-1 RNA region outside of the PPT. ODN G serves as a further control, with a similar passenger strand sequence compared to ODN A but a non-complementary HIV-1 PPT sequence. c Sequence of the extended polypurine tract of HIV-1 recognized by the viral RNase H, whose specific cleavage site is indicated by an arrow