T30177, an
oligonucleotide composed of only
deoxyguanosine and
thymidine, is 17
nucleotides in length and contains single phosphorothioate internucleoside linkages at its 5' and 3' ends for stability. This
oligonucleotide does not share significant primary sequence homology with or possess any complementary (antisense) sequence motifs to the human immunodeficiency virus type 1 (HIV-1) genome.
T30177 inhibited replication of multiple laboratory strains of HIV-1 in human T-cell lines, peripheral blood lymphocytes, and macrophages.
T30177 was also found to be capable of inhibiting multiple clinical isolates of HIV-1 and preventing the cytopathic effect of HIV-1 in primary CD4+ T lymphocytes. In assays with human peripheral blood lymphocytes there was no observable toxicity associated with
T30177 at the highest concentration tested (100 microM), while the median inhibitory concentration was determined to be in the range of 0.1 to 1.0 microM for the clinical isolates tested, resulting in a high therapeutic index for this
drug. In temporal studies, the kinetics of addition of
T30177 to infected cell cultures indicated that, like the known viral adsorption blocking agents
dextran sulfate and
Chicago sky blue,
T30177 needed to be added to cells during or very soon after
viral infection. However, analysis of
nucleic acids extracted at 12 h postinfection from cells treated with
T30177 at the time of
virus infection established the presence of unintegrated viral
cDNA, including circular proviral
DNA, in the treated cells. In vitro analysis of viral
enzymes revealed that
T30177 was a potent inhibitor of
HIV-1 integrase, reducing enzymatic activity by 50% at concentrations in the range of 0.050 to 0.09 microM.
T30177 was also able to inhibit viral
reverse transcriptase activity; however, the 50% inhibitory value obtained was in the range of 1 to 10 microM, depending on the template used in the enzymatic assay. No observable inhibition of viral
protease was detected at the highest concentration of
T30177 used (10 microM). In experiments in which
T30177 was removed from infected cell cultures at 4 days post-HIV-1
infection, total suppression of virus production was observed for more than 27 days. PCR analysis of
DNA extracted from cells treated in this fashion was unable to detect the presence of
viral DNA 11 days after removal of the
drug from the infected cell cultures. The ability of
T30177 to inhibit both laboratory and clinical isolates of HIV-1 and the experimental data which suggest that
T30177 represents a novel class of
integrase inhibitors indicate that this compound is a viable candidate for evaluation as a therapeutic agent against HIV-1 in humans.