Publications (41) View all
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Article: Antiretroviral agents effectively block HIV replication after cell-to-cell transfer.
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ABSTRACT: Cell-to-cell transmission of HIV has been proposed as a mechanism contributing to virus escape to the action of antiretrovirals and a mode of HIV persistence during antiretroviral therapy. Here, cocultures of infected HIV-1 cells with primary CD4(+) T cells or lymphoid cells were used to evaluate virus transmission and the effect of known antiretrovirals. Transfer of HIV antigen from infected to uninfected cells was resistant to the reverse transcriptase inhibitors (RTIs) zidovudine (AZT) and tenofovir, but was blocked by the attachment inhibitor IgGb12. However, quantitative measurement of viral DNA production demonstrated that all anti-HIV agents blocked virus replication with similar potency to cell-free virus infections. Cell-free and cell-associated infections were equally sensitive to inhibition of viral replication when HIV-1 long terminal repeat (LTR)-driven green fluorescent protein (GFP) expression in target cells was measured. However, detection of GFP by flow cytometry may incorrectly estimate the efficacy of antiretrovirals in cell-associated virus transmission, due to replication-independent Tat-mediated LTR transactivation as a consequence of cell-to-cell events that did not occur in short-term (48-h) cell-free virus infections. In conclusion, common markers of virus replication may not accurately correlate and measure infectivity or drug efficacy in cell-to-cell virus transmission. When accurately quantified, active drugs blocked proviral DNA and virus replication in cell-to-cell transmission, recapitulating the efficacy of antiretrovirals in cell-free virus infections and in vivo.Journal of Virology 06/2012; 86(16):8773-80. · 5.40 Impact Factor -
Article: Compensatory mutations rescue the virus replicative capacity of VIRIP-resistant HIV-1.
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ABSTRACT: VIRIP has been identified as a highly specific natural inhibitor of HIV-1 that blocks HIV-1 gp41-dependent fusion by interacting with the gp41 fusion peptide. Two analogues of VIRIP (VIR-353 and VIR-576) with a few amino acid changes increase its antiretroviral potency by two orders of magnitude in cell culture. VIR-576 has been shown effective in a phase I/II clinical trial. Resistance to VIRIP and its analogue VIR-353 were generated after long-term passage in cell culture suggesting a high genetic barrier to resistance. Mutations conferring resistance to VIRIP and VIR-353 significantly reduced virus fitness. However, accumulation of additional mutations rescued the replication capacity of the virus while retaining resistance to VIR-353 and full sensitivity to T20. Combinations of VIR-353 and T20 had an additive effect on the inhibition of wild type HIV-1 replication, but only a single agent was active when combinations were tested against T20-resistant HIV-1, suggesting that both gp41 peptides do not interfere with each other in their binding to gp41. Our results provide additional support to the development of a new class of antiretroviral agents targeting gp41-dependent fusion.Antiviral research 12/2011; 92(3):479-83. · 3.61 Impact Factor -
Article: Development of resistance to VIR-353 with cross-resistance to the natural HIV-1 entry virus inhibitory peptide (VIRIP).
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ABSTRACT: Virus-inhibitory peptide (VIRIP) has been identified as a component of human hemofiltrate that blocks HIV-1 gp41-dependent fusion by interacting with the fusion peptide. A VIRIP analogue (VIR-576) has been shown to be effective in a phase I/II clinical trial. We have evaluated the activity and mechanism of HIV-1 resistance to VIRIP and its analogue, VIR-353. Anti-HIV activity and passage of HIV-1 strains in cell culture were used to generate and identify mutations that confer resistance to VIRIP and VIR-353. Recombinant viruses harboring the most relevant mutations were generated and characterized. VIRIP and VIR-353 showed anti-HIV-1 activity with EC(50) of 28 and 0.3 μmol/l, respectively, and were active against virus resistant to BMS-155, AMD3100, T20, TAK-779 or nevirapine. Time of addition experiments showed that VIR-353 targets a time/site of action corresponding to gp41-dependent fusion. VIR-353-resistant virus was generated after 450 days in cell culture, suggesting a high genetic barrier for resistance. The VIR-353-resistant virus was cross-resistant to VIRIP but remained sensitive to T20, AMD3100 or zidovudine. Recombination of gp41 into a wild-type backbone partially recovered the resistant phenotype, but both gp120 and gp41 from the resistant virus were necessary to restore resistance to VIRIP or VIR-353. Site-directed mutagenesis confirmed the role of specific mutations and identified a combination of three mutations (A433T/V489I/V570I) as the most relevant to VIRIP resistance. VIRIP may interact with a region of gp41 that is essential for fusion but not the fusion peptide. Our results highlight interactions between gp41 and gp120 that may be required during the fusion process.AIDS (London, England) 05/2011; 25(13):1557-83. · 4.91 Impact Factor -
Article: β5 integrin is the major contributor to the αVintegrin-mediated blockade of HIV-1 replication.
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ABSTRACT: Monocytes and macrophages are targets of HIV-1 infection and play critical roles in multiple aspects of viral pathogenesis. During the differentiation of monocytes to macrophages, adhesion molecules such as integrins are upregulated; therefore, they provide signals that control the process and subsequently may render macrophages more susceptible to HIV-1 infection. Previous work demonstrated that blocking α(v)-containing integrins triggered a signal transduction pathway leading to the inhibition of NF-κB-dependent HIV-1 transcription. In this paper, we show the influence of the different α(v)-coupled β integrins in HIV-1 replication in macrophages. Inhibition of β integrins, either by specific mAbs, small arginine-glycine-aspartic acid (RGD) mimetic compounds, or RNA interference, showed that integrin β(5) was the major contributor to the integrin-mediated blockade of HIV-1 replication. Importantly, such inhibition did not induce changes in cell adhesion to the substrate. In conclusion, our results reveal a significant role of the integrin dimer α(v)β(5) in HIV-1 infection of macrophages.The Journal of Immunology 01/2011; 186(1):464-70. · 5.79 Impact Factor -
Article: ADS-J1 inhibits HIV-1 entry by interacting with gp120 and does not block fusion-active gp41 core formation.
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ABSTRACT: We had shown that virus resistance to ADS-J1 was associated with amino acid changes in the envelope glycoprotein, mostly located in the gp120 coding region. Time-of-addition and endocytic virus transfer assays clearly demonstrated that ADS-J1 behaved as a gp120 inhibitor. ADS-J1-resistant virus was cross-resistant to the polyanion dextran sulfate, and recombination of gp120 recovered only the ADS-J1-resistant phenotype. In summary, ADS-J1 blocks an early step of virus entry that appears to be driven by gp120 alone.Antimicrobial Agents and Chemotherapy 10/2010; 54(10):4487-92. · 4.84 Impact Factor
