Reassessment of enfuvirtide's role in the management of HIV-1 infection

Potential use of rapamycin in HIV infection

The strong need for the development of alternative anti-HIV agents is primarily due to the emergence of strain-resistant viruses, the need for sustained adherence to complex treatment regimens and the toxicity of currently used antiviral drugs. This review analyzes proof of concept studies indicating that the immunomodulatory drug rapamycin (RAPA) possesses anti-HIV properties both in vitro and in vivo that qualifies it as a potential new anti-HIV drug. It represents a literature review of published studies that evaluated the in vitro and in vivo activity of RAPA in HIV. RAPA represses HIV-1 replication in vitro through different mechanisms including, but not limited, to down regulation of CCR5. In addition RAPA synergistically enhances the anti-HIV activity of entry inhibitors such as vicriviroc, aplaviroc and enfuvirtide in vitro. RAPA also inhibits HIV-1 infection in human peripheral blood leucocytes-SCID reconstituted mice. In addition, a prospective nonrandomized trial of HIV patient series receiving RAPA monotherapy after liver transplantation indicated significantly better control of HIV and hepatitis C virus (HCV) replication among patients taking RAPA monotherapy. Taken together, the evidence presented in this review suggests that RAPA may be a useful drug that should be evaluated for the prevention and treatment of HIV-1 infection.

Antiviral activity, pharmacokinetics, and safety of BMS-488043, a novel oral small-molecule HIV-1 attachment inhibitor, in HIV-1-infected subjects

BMS-488043 is a novel and unique oral small-molecule inhibitor of the attachment of human immunodeficiency virus type 1 (HIV-1) to CD4(+) lymphocytes. The antiviral activity, pharmacokinetics, viral susceptibility, and safety of BMS-488043 were evaluated in an 8-day monotherapy trial. Thirty HIV-1-infected study subjects were randomly assigned to sequential, safety-guided dose panels of 800 and 1,800 mg BMS-488043 or a matched placebo in a 4:1 ratio, and the drug was administered every 12 h with a high-fat meal for 7 days and on the morning of day 8. Dose-related, albeit less-than-dose-proportional, increases in plasma BMS-488043 concentrations were observed. Mean plasma HIV-1 RNA decreases from the baseline for the BMS-488043 800- and 1,800-mg dose groups on day 8 were 0.72 and 0.96 log(10) copies/ml, respectively, compared with 0.02 log(10) copies/ml for the placebo group. A lower baseline BMS-488043 50% effective concentration (EC(50)) in the active-treatment groups was predictive of a greater antiviral response. Although absolute drug exposure was not associated with an antiviral response, the trough concentration (C(trough)), adjusted by the baseline EC(50) (C(trough)/EC(50)), was associated with antiviral activity. During dosing, four subjects experienced >10-fold reductions in viral susceptibility to BMS-488043, providing further support of the direct antiviral mechanism of BMS-488043. BMS-488043 was generally safe and well tolerated. These results suggest that further development of this novel class of oral HIV-1 attachment inhibitors is warranted.

Inhibition of Nipah virus infection in vivo: targeting an early stage of paramyxovirus fusion activation during viral entry

In the paramyxovirus cell entry process, receptor binding triggers conformational changes in the fusion protein (F) leading to viral and cellular membrane fusion. Peptides derived from C-terminal heptad repeat (HRC) regions in F have been shown to inhibit fusion by preventing formation of the fusogenic six-helix bundle. We recently showed that the addition of a cholesterol group to HRC peptides active against Nipah virus targets these peptides to the membrane where fusion occurs, dramatically increasing their antiviral effect. In this work, we report that unlike the untagged HRC peptides, which bind to the postulated extended intermediate state bridging the viral and cell membranes, the cholesterol tagged HRC-derived peptides interact with F before the fusion peptide inserts into the target cell membrane, thus capturing an earlier stage in the F-activation process. Furthermore, we show that cholesterol tagging renders these peptides active in vivo: the cholesterol-tagged peptides cross the blood brain barrier, and effectively prevent and treat in an established animal model what would otherwise be fatal Nipah virus encephalitis. The in vivo efficacy of cholesterol-tagged peptides, and in particular their ability to penetrate the CNS, suggests that they are promising candidates for the prevention or therapy of infection by Nipah and other lethal paramyxoviruses.

An HIV-1 integrase genotype assay for the detection of drug resistance mutations

BACKGROUND

The integrase inhibitors (e.g. Raltegravir) are a new class of antiretroviral drugs that have recently become available for the treatment of patients with multi-drug resistant HIV-1 within Australia. The emergence of mutations that confer resistance to the integrase inhibitors has been observed in vivo; however, no commercial genotyping assay is currently available to screen for resistance to these drugs.

METHODS

The HIV-1 integrase gene was amplified from plasma-derived HIV-1 viral RNA via reverse transcription-polymerase chain reaction and genotype determined via population DNA sequencing. Drug resistance mutations and polymorphisms were detected using the Stanford University online HIV database. Assay sensitivity and reproducibility were determined using clinical and laboratory-derived samples.

RESULTS

Our in-house assay was capable of genotyping the integrase gene from all samples tested (n = 30) of HIV-1 subtypes B, C, D, F, CFR01_AE and CRF02_AG and can amplify the integrase region from plasma samples containing as few as 50 HIV RNA copies/mL. The assay is highly reproducible (average nucleotide concordance = 99.6%, n = 4) and is capable of detecting resistance-associated mutations.

CONCLUSIONS

This assay is suitable for routine drug resistance screening of plasma samples from HIV-infected patients receiving integrase inhibitor antiretroviral drugs and also serves as a useful research tool.