Polyanionic (i.e., polysulfonate) dendrimers can inhibit the replication of human immunodeficiency virus by interfering with both virus adsorption and later steps (reverse transcriptase/integrase) in the virus replicative cycle.

Polyanionic dendrimers were synthesized and evaluated for their antiviral effects. Phenyldicarboxylic acid (BRI6195) and naphthyldisulfonic acid (BRI2923) dendrimers were found to inhibit the replication of human immunodeficiency virus type 1 (HIV-1; strain III(B)) in MT-4 cells at a EC(50) of 0.1 and 0.3 microg/ml, respectively. The dendrimers were not toxic to MT-4 cells up to the highest concentrations tested (250 microg/ml). These compounds were also effective against various other HIV-1 strains, including clinical isolates, HIV-2 strains, simian immunodeficiency virus (SIV, strain MAC(251)), and HIV-1 strains that were resistant to reverse transcriptase inhibitors. HIV strains containing mutations in the envelope glycoprotein gp120 (engendering resistance to known adsorption inhibitors) displayed reduced sensitivity to the dendrimers. The compounds inhibited the binding of wild-type virus and recombinant virus (containing wild-type gp120) to MT-4 cells at concentrations comparable to those that inhibited the replication of HIV-1(III(B)) in these cells. Cellular uptake studies indicated that BRI2923, but not BRI6195, permeates into MT-4 and CEM cells. Accordingly, the naphtyldisulfonic acid dendrimer (BRI2923) proved able to inhibit later steps of the replication cycle of HIV, i.e., reverse transcriptase and integrase. NL4.3 strains resistant to BRI2923 were selected after passage of the virus in the presence of increasing concentrations of BRI2923. The virus mutants showed 15-fold reduced sensitivity to BRI2923 and cross-resistance to known adsorption inhibitors. However, these virus mutants were not cross-resistant to reverse transcriptase inhibitors or protease inhibitors. We identified several mutations in the envelope glycoprotein gp120 gene (i.e., V2, V3, and C3, V4, and C4 regions) of the BRI2923-resistant NL4.3 strains that were not present in the wild-type NL4.3 strain, whereas no mutations were found in the reverse transcriptase or integrase genes.

Viral entry as the primary target for the anti-HIV activity of chicoric acid and its tetra-acetyl esters.

The antiviral activity of L-chicoric acid against HIV-1 has been attributed previously to the inhibition of HIV-1 integration. This conclusion was based on the inhibition of integrase activity in enzymatic assays and the isolation of a resistant HIV strain with a mutation (G140S) in the integrase gene. Here we show that the primary antiviral target of L-CA and its analogs in cell culture is viral entry. L- and D-chicoric acid (L-CA and D-CA) and their respective tetra-acetyl esters inhibit the replication of HIV-1 (III(B) and NL4.3) and HIV-2 (ROD) in MT-4 cells at a 50% effective concentration (EC(50)) ranging from 1.7 to 70.6 microM. In a time-of-addition experiment, L-CA, D-CA, L-CATA, and D-CATA were found to interfere with an early event in the viral replication cycle. Moreover, L-CA, D-CA, and their analogs did not inhibit the replication of virus strains that were resistant toward polyanionic and polycationic compounds at subtoxic concentrations. Furthermore, HIV-1 strains resistant to L-CA and D-CA were selected in the presence of L-CA and D-CA, respectively. Mutations were found in the V2, V3, and V4 loop region of the envelope glycoprotein gp120 of the L-CA and D-CA-resistant NL4.3 strains that were not present in the wild-type NL4.3 strain. Recombination of the gp120 gene of the L-CA and D-CA resistant strain in a NL4.3 wild-type molecular clone fully rescued the phenotypic resistance toward L-CA and D-CA. No significant mutations were detected in the integrase gene of the drug-resistant virus strains. Although inhibition of HIV integrase activity by L-CA and its derivatives was confirmed in an oligonucleotide-driven assay, integrase carrying the G140S mutation was inhibited to the same extent as the wild-type integrase.