Mechanism of inhibition of HIV-1 infectionin vitroby guanine-rich oligonucleotides modified at the 5′ terminal by dimethoxytrityl residue

Oligodeoxyribonucleotides (ODN) linked at their 5'-end with dimethoxytrityl (DmTr) residue were examined for antiviral activities against human immunodeficiency virus type 1 (HIV-1). We found that guanine-rich oligonucleotides exhibit anti-HIV activity upon 5'-end modification with DmTr. One oligonucleotide, DmTr-TGGGAGGTGGGTCTG (SA-1042), showed potent anti-HIV activity in vitro. A greater than 95% reduction of infectivity was observed if the cells were treated with 10 micrograms/ml of SA-1042 at the time of viral infection, PCR analysis confirmed that there was a significant reduction of provirus in the cells exposed to virus in the presence of SA-1042. By contrast, no inhibition was observed if the cells were treated with the oligomer 1 h after virus adsorption. SA-1042 prevented syncytium formation between chronically infected cells and CD4 positive uninfected cells. Furthermore, the oligomer interfered the interaction of purified gp120 to the CD4 receptor. By contrast, SA-1042 had no inhibitory effect on chronically HIV-infected cells. These results strongly suggest that the DMTr-ODNs with appropriate base sequences antagonize HIV-1 infection during the stage of virus-cell interaction.