Antiviral and Biological Properties of Dimethoxytrityl-Linked Guanine-Rich Oligodeoxynucleotides that Inhibit Replication by Primary Clinical Human Immunodeficiency virus Type 1 Isolates

Abstract

We have investigated the biological and antiviral properties of a dimethoxytrityl (DmTr)-linked guanine (G)-rich oligodeoxynucleotide (ODN) with a phosphodiester linkage, SA-1042 (5′ DmTr-TGGGAGGTGGGTCTG 3′), that has been shown to exhibit potent inhibition of human immunodeficiency virus type 1 (HIV-1)-induced cytopathic effect. In a study of the modification of the sequences of SA-1042, it was revealed that the inhibitory effect is exhibited in a highly sequence-specific manner, at the G-rich core sequence (5′ TGGG 3′), especially near the 5′ end. In a study of the gel mobility—antiviral activity relationship, DmTr modification and the G-rich core sequence of DmTr-ODNs were indispensable for the formation of a hyperstructure and for their antiviral activity. HIV-induced syncytium formation in co-cultures of MOLT-4 cells and chronically infected MOLT-4/HIV-1_IIIB cells was blocked by SA-1042 at a 50% inhibitory concentration (IC₅₀) of 6.5 μg mL-1. Time-of-addition studies revealed that SA-1042 blocked virus attachment to cells. The susceptibility of 10 fresh HIV-1 clinical isolates [nine with syncytium-inducing (SI) phenotypes and one with a non-SI phenotype], and five laboratory strains with both phenotypes to SA-1042 was assessed by a focus reduction assay using CD4+ HeLa cells or by p24 antigen quantitative assay using human peripheral blood mononuclear cells. SA-1042 was active in both assays. These results suggest that SA-1042; which inhibits the adsorption and fusion steps of HIV-1 replication through its hyperstructure formation and the G-rich core sequence, exhibits potent activity against primary clinical isolates.