In vitro inhibition of HIV-1 by Met-SDF-1β alone or in combination with antiretroviral drugs

Compounds that can block the CXCR4 chemokine receptor are a promising new class of antiretroviral agents. In these experiments we studied the effect of a modified form of the native stromal cell-derived factor- 1 (SDF-1), Met-SDF-1\u3b2. The in vitro susceptibility of two different CXCR4-tropic HIV-1 strains was determined. Antiviral effect was assessed by the reduction of p24 antigen production in PHA-stimulated peripheral blood mononuclear cells with exposure to the modified SDF-1 molecule. The 50% inhibitory concentrations (IC50) were derived from six separate experiments. The IC50 against the two HIV-1 isolates was in 1.0-2.8 \u3bcg/ml range for Met-SDF-1\u3b2. Met-SDF-1\u3b2 showed synergy to additivity with either zidovudine or nelfinavir at IC75, IC90 and IC95. Additivity was seen when Met-SDF-1\u3b2 was combined with efavirenz. No cellular toxicity was observed at the highest concentrations when these agents were used either singly or in combination. This compound is a promising new candidate in a receptor-based approach to HIV-1 infection in conjunction with currently available combination antiretroviral drug therapies

HIV-1 protease inhibitors in development

Several pharmaceutical companies have developed an increasing number of second generation protease inhibitors (PI) during the last few years. Many of these compounds have been in preclinical trials and some are now in clinical use. All drugs in this category have been designed to be well absorbed and overcome the crucial problem of cross-resistance within this class of compounds. Taking into account the rapid occurrence of PI cross-resistance, clinicians who are treating patients with the HIV-1 infection will need new active PIs in the near future. The clinical and antiviral efficacy of the new molecules versus the older PIs will be investigated through comparative trials that are likely to be completed over the next 12 months. These third-generation PIs currently in development will be the subject of our review

A genotypic analysis of patients receiving Zidovudine with either Lamivudine, Didanosine or Zalcitabine dual therapy using the LiPA point mutation assay to detect genotypic variation at codons 41, 69, 70, 74, 184 and 215

Background: The Murex-Innogenetics LiPA HIV-1 RT assay can be used to identify the presence of mutations of the reverse transcriptase gene at codons 41, 69, 70, 74, 184 and 215 of HIV-1, which have been shown to confer resistance to the nucleoside analogs Zidovudine (ZDV), Lamivudine (3TC), Didanosine (ddI) and Zalcitabine (ddC). The M184V mutation of the reverse transcriptase gene of HIV-1 has been associated with resistance to 3TC, ddC and ddI. This mutation has also been observed in patients receiving ZDV ddC and ZDV ddI. We used LiPA HIV-1 RT assay to identify the presence of either consensus methionine 184 or the mutant valine 184 with three groups of patients who were treated with ZDV:3TC, ZDV:ddI or ZDV:ddC combination therapy. Objecti6es: The aim of our study was to determine the viral genotype of patients who were considered to be failing therapy, by two ways: using sequencing and LiPA assays. In particular we were interested in establishing a possible correlation between these methods. Study design: The study group consisted of a consecutive series of 33 patients with a treatment failure, 18 of whom received ZDV 3TC therapy, seven received ZDV ddI and eight received ZDV ddC therapy. We also examined a small cohort of seven seroconverters. Results: The M184V mutation was observed in 47.0% of patients receiving ZDV 3TC combination therapy but was not observed in either patient group receiving either ddI or ddC as co-therapy with ZDV. There was no evidence of the L74V mutation in our study group in either the ZDV:ddI or ZDV:ddC combination therapy group. We found the frequency of the K70R mutation to be higher in patients treated with ZDV:ddI (P 0.033) or ZDV:ddC (P 0.3) when compared with patients treated with ZDV:3TC. Conclusion: The LiPA assay allowed for the rapid detection of wild type and amino acid variations at key positions conferring resistance to the most used antiviral RT inhibitors. This represented a rapid, quite sensitive, and simple genotyping test. For these reasons the LiPA assay proved to be useful in studying genetic resistance in large screenings, when key RT mutations could be useful in guiding an effective HIV-1 suppressing regimen

Virological response in multidrug-experienced HIV-1-infected subjects failing highly active combination regimens after shifting from lamivudine to didanosine

The aim of this study (the RESCUE trial) was to verify the effect of a shift from a lamivudine-containing to a didanosine-containing regimen on viral replication in HIV-1-infected subjects who had experienced prior treatment failure. Sixteen patients (didanosine-experienced in 14/16 cases) were consecutively enrolled: eight patients shifted from lamivudine to didanosine without other changes in their drug regimen. The other eight shifted from lamivudine to didanosine and changed one or more of their other drugs according to their physician's judgement. At the time of the regimen shift, all the subjects exhibited a high-level phenotypic resistance to both zidovudine and lamivudine with changes at codons 70-219 in 100% of cases, at codon 215 in 13 of 16 patients, and the M184V substitution in 13/16 patients. Phenotypic susceptibility to didanosine was maintained in the majority of cases (14/16) despite the high prevalence of changes at codon 184. A statistically significant decrease in viral load (P<0.005) without a significant increase in CD4 lymphocytes (P=0.514) was observed after 3 and 6 months from the introduction of the didanosine-containing regimen. These findings suggest the possibility of achieving a viral load response to didanosine-containing regimens in patients with reverse transcriptase (RT) M184V mutations who were previously treated with this drug and its possible use in salvage combinations

Loss of lamivudine resistance in a zidovudine and lamivudine dual-resistant HIV-1 isolate after discontinuation of in vitro lamivudine drug pressure

We examined the in vitro phenotypic and genotypic profiles of an extensively passaged human immunodeficiency virus type 1 clinical isolate which has been selected for lamivudine resistance, with an M184V mutation in a zidovudine-resistant genetic background, and then cultured with zidovudine alone. Our passaging strategy led to a decrease in lamivudine IC50 values, which were comparable to those prior to lamivudine exposure, and the genotypic restoration of the wild-type sequence at codon 184 of reverse transcriptase

Aminooxypentane-RANTES, an inhibitor of R5 human immunodeficiency virus type 1, increases the interferon gamma to interleukin 10 ratio without impairing cellular proliferation

Studies have demonstrated that the beta-chemokines RANTES, MIP-1 alpha, and MIP-1 beta suppress human immunodeficiency type 1 (HIV-1) replication in vitro, Infection with HIV-1 requires expression of CD4 antigen and the chemokine receptor CXCR4 (X4) or CCR5 (R5) on the surface of target cells. The engagement of these receptors with the viral surface proteins is essential for the membrane fusion process. This study investigated the anti-HIV-1 activity of a derivative of RANTES, the CCR5 antagonist aminooxypentane (AOP)-RANTES, on R5 HIV-1 isolates in peripheral blood mononuclear cells, In drug exposure experiments, AOP-RANTES efficiently inhibited viral replication of HIV-1 R5 strains, with a viral breakthrough observed after the withdrawal of the compound, The HIV-1-specific proliferative capacity was maintained under all conditions when compared with controls, An increase in IFN-gamma production accompanied by a parallel decrease in the generation of IL-10 was observed following the in vitro exposure of cells to AOP-RANTES in the presence of three of four HIV-1 R5 isolates. These experiments confirmed that the chemokine receptor antagonist AOP-RANTES was effective as an inhibitor of HIV-1 R5 strain infectivity in peripheral blood mononuclear cells, The capacity of this compound to maintain HIV-1-specific proliferative activity with a shift toward a type 1 cytokine profile makes this compound a unique molecule, one adopting an immunological pathway to limit HIV-1 infection

In vitro inhibition of HIV-1 by Met-SDF-1beta alone or in combination with antiretroviral drugs

Compounds that can block the CXCR4 chemokine receptor are a promising new class of antiretroviral agents. In these experiments we studied the effect of a modified form of the native stromal cell-derived factor-1 (SDF-1), Met-SDF-1beta. The in vitro susceptibility of two different CXCR4-tropic HIV-1 strains was determined. Antiviral effect was assessed by the reduction of p24 antigen production in PHA-stimulated peripheral blood mononuclear cells with exposure to the modified SDF-1 molecule. The 50% inhibitory concentrations (IC50) were derived from six separate experiments. The IC50 against the two HIV-1 isolates was in 1.0-2.8 microg/ml range for Met-SDF-1beta. Met-SDF-1beta showed synergy to additivity with either zidovudine or nelfinavir at IC75 IC90 and IC95. Additivity was seen when Met-SDF-1beta was combined with efavirenz. No cellular toxicity was observed at the highest concentrations when these agents were used either singly or in combination. This compound is a promising new candidate in a receptor-based approach to HIV-1 infection in conjunction with currently available combination antiretroviral drug therapies

Combination of CCR5 and CXCR4 Inhibitors in Therapy of Human Immunodeficiency Virus Type 1 Infection: In Vitro Studies of Mixed Virus Infections

We studied the combined anti-human immunodeficiency virus type 1 (HIV-1) effects of a derivative of stroma-derived factor 1β (SDF-1β), Met-SDF-1β, and a modified form of RANTES, aminooxypentane (AOP)-RANTES. The antiviral agents were tested singly or in combination at 95 and 99% virus inhibitory concentrations. Clinical R5 and X4 HIV-1 isolates were used. AOP-RANTES inhibited R5 but not X4 viruses, whereas Met-SDF-1β had the opposite effect. Combinations of these compounds inhibited mixed infections with R5 and X4 viruses (95 to 99%), whereas single drugs were less inhibitory (32 to 61%). Combinations of R5 and X4 inhibitors are promising and deserve further evaluation