Inhibitory Mechanism of the CXCR4 Antagonist T22 against Human Immunodeficiency Virus Type 1 Infection

ABSTRACT We recently reported that a cationic peptide, T22 ([Tyr5,12, Lys7]-polyphemusin II), specifically inhibits human immunodeficiency virus type 1 (HIV-1) infection mediated by CXCR4 (T. Murakami et al., J. Exp. Med. 186:1389–1393, 1997). Here we demonstrate that T22 effectively inhibits replication of T-tropic HIV-1, including primary isolates, but not of non-T-tropic strains. By using a panel of chimeric viruses between T- and M-tropic HIV-1 strains, viral determinants for T22 susceptibility were mapped to the V3 loop region of gp120. T22 bound to CXCR4 and interfered with stromal-cell-derived factor-1α–CXCR4 interactions in a competitive manner. Blocking of anti-CXCR4 monoclonal antibodies by T22 suggested that the peptide interacts with the N terminus and two of the extracellular loops of CXCR4. Furthermore, the inhibition of cell-cell fusion in cells expressing CXCR4/CXCR2 chimeric receptors suggested that determinants for sensitivity of CXCR4 to T22 include the three extracellular loops of the coreceptor.

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Baseline Resistance of Primary Human Immunodeficiency Virus Type 1 Strains to the CXCR4 Inhibitor AMD3100

Journal of Virology ◽

10.1128/jvi.01303-08 ◽

2008 ◽

Vol 82 (23) ◽

pp. 11695-11704 ◽

Cited By ~ 15

Author(s):

Jessamina E. Harrison ◽

Jonathan B. Lynch ◽

Luz-Jeannette Sierra ◽

Leslie A. Blackburn ◽

Neelanjana Ray ◽

...

Keyword(s):

Human Immunodeficiency Virus ◽

Human Immunodeficiency Virus Type ◽

Virus Type ◽

Antiviral Agents ◽

Viral Envelope ◽

Cxcr4 Antagonist ◽

Immunodeficiency Virus ◽

Env Protein ◽

Hiv 1

ABSTRACT We screened a panel of R5X4 and X4 human immunodeficiency virus type 1 (HIV-1) strains for their sensitivities to AMD3100, a small-molecule CXCR4 antagonist that blocks HIV-1 infection via this coreceptor. While no longer under clinical development, AMD3100 is a useful tool with which to probe interactions between the viral envelope (Env) protein and CXCR4 and to identify pathways by which HIV-1 may become resistant to this class of antiviral agents. While infection by most virus strains was completely blocked by AMD3100, we identified several R5X4 and X4 isolates that exhibited plateau effects: as the AMD3100 concentration was increased, virus infection and membrane fusion diminished to variable degrees. Once saturating concentrations of AMD3100 were achieved, further inhibition was not observed, indicating a noncompetitive mode of viral resistance to the drug. The magnitude of the plateau varied depending on the virus isolate, as well as the cell type used, with considerable variation observed when primary human T cells from different human donors were used. Structure-function studies indicated that the V1/V2 region of the R5X4 HIV-1 isolate DH12 was necessary for AMD3100 resistance and could confer this property on two heterologous Env proteins. We conclude that some R5X4 and X4 HIV-1 isolates can utilize the AMD3100-bound conformation of CXCR4, with the efficiency being influenced by both viral and host factors. Baseline resistance to this CXCR4 antagonist could influence the clinical use of such compounds.

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Sensitivity to a Nonpeptidic Compound (RPR103611) Blocking Human Immunodeficiency Virus Type 1 Env-Mediated Fusion Depends on Sequence and Accessibility of the gp41 Loop Region

Journal of Virology ◽

10.1128/jvi.74.5.2142-2150.2000 ◽

2000 ◽

Vol 74 (5) ◽

pp. 2142-2150 ◽

Cited By ~ 31

Author(s):

Béatrice Labrosse ◽

Carole Treboute ◽

Marc Alizon

Keyword(s):

Human Immunodeficiency Virus ◽

Drug Resistance ◽

Human Immunodeficiency Virus Type ◽

Virus Type ◽

Conformational Changes ◽

Loop Region ◽

Immunodeficiency Virus ◽

The Stability ◽

Hiv 1

ABSTRACT The triterpene RPR103611 is an efficient inhibitor of membrane fusion mediated by the envelope proteins (Env, gp120-gp41) of CXCR4-dependent (X4) human immunodeficiency virus type 1 (HIV-1) strains, such as HIV-1LAI (LAI). Other X4 strains, such as HIV-1NDK (NDK), and CCR5-dependent (R5) HIV-1 strains, such as HIV-1ADA (ADA), were totally resistant to RPR103611. Analysis of chimeric LAI-NDK Env proteins identified a fragment of the NDK gp41 ectodomain determining drug resistance. A single difference at position 91, leucine in LAI and histidine in NDK, apparently accounted for their sensitivity or resistance to RPR103611. We had previously identified a mutation of isoleucine 84 to serine in a drug escape LAI variant. Both I84 and L91 are located in the “loop region” of gp41 separating the proximal and distal helix domains. Nonpolar residues in this region therefore appear to be important for the antiviral activity of RPR103611 and are possibly part of its target. However, another mechanism had to be envisaged to explain the drug resistance of ADA, since its gp41 loop region was almost identical to that of LAI. Fusion mediated by chimeric Env consisting of LAI gp120 and ADA gp41, or the reciprocal construct, was fully blocked by RPR103611. The gp120-gp41 complex of R5 strains is stable, relative to that of X4 strains, and this stability could play a role in their drug resistance. Indeed, when the postbinding steps of ADA infection were performed under mildly acidic conditions (pH 6.5 or 6.0), a treatment expected to favor dissociation of gp120, we achieved almost complete neutralization by RPR103611. The drug resistance of NDK was partially overcome by preincubating virus with soluble CD4, a gp120 ligand inducing conformational changes in the Env complex. The antiviral efficacy of RPR103611 therefore depends on the sequence of the gp41 loop and the stability of the gp120-gp41 complex, which could limit the accessibility of this target.

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1,25-Dihydroxyvitamin D3 Upregulates Functional CXCR4 Human Immunodeficiency Virus Type 1 Coreceptors in U937 Minus Clones: NF-κB-Independent Enhancement of Viral Replication

Journal of Virology ◽

10.1128/jvi.72.10.8380-8383.1998 ◽

1998 ◽

Vol 72 (10) ◽

pp. 8380-8383 ◽

Cited By ~ 19

Author(s):

Priscilla Biswas ◽

Manuela Mengozzi ◽

Barbara Mantelli ◽

Fanny Delfanti ◽

Andrea Brambilla ◽

...

Keyword(s):

Human Immunodeficiency Virus ◽

Human Immunodeficiency Virus Type ◽

Virus Type ◽

Vitamin D3 ◽

Dihydroxyvitamin D3 ◽

1,25 Dihydroxyvitamin D3 ◽

Immunodeficiency Virus ◽

Stromal Cell Derived Factor ◽

Hiv 1

ABSTRACT U937 cell clones which sustain efficient or poor replication of human immunodeficiency virus type 1 (HIV-1) (referred to herein as plus clones and minus clones, respectively) have been previously described. 1,25-Dihydroxyvitamin D3 (vitamin D3) potently induced HIV-1 replication and proviral DNA accumulation in minus clones but not in plus clones. Vitamin D3 did not induce NF-κB activation but selectively upregulated CXCR4 expression in minus clones. The CXCR4 ligand stromal-cell derived factor-1 induced Ca2+ fluxes and inhibited both constitutive and vitamin D3-enhanced HIV replication in minus clones.

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Distinct Functional Sites for Human Immunodeficiency Virus Type 1 and Stromal Cell-Derived Factor 1α on CXCR4 Transmembrane Helical Domains

Journal of Virology ◽

10.1128/jvi.79.20.12667-12673.2005 ◽

2005 ◽

Vol 79 (20) ◽

pp. 12667-12673 ◽

Cited By ~ 50

Author(s):

Shaomin Tian ◽

Won-Tak Choi ◽

Dongxiang Liu ◽

James Pesavento ◽

Youli Wang ◽

...

Keyword(s):

Human Immunodeficiency Virus ◽

Cell Fusion ◽

Human Immunodeficiency Virus Type ◽

Virus Type ◽

Stromal Cell ◽

Functional Sites ◽

Immunodeficiency Virus ◽

Stromal Cell Derived Factor ◽

Hiv 1

ABSTRACT The entry of human immunodeficiency virus type 1 (HIV-1) into the cell is initiated by the interaction of the viral surface envelope protein with two cell surface components of the target cell, CD4 and a chemokine coreceptor, usually CXCR4 or CCR5. The natural ligand of CXCR4 is stromal cell-derived factor 1α (SDF-1α). Whereas the overlap between HIV-1 and SDF-1α functional sites on the extracellular domains of CXCR4 has been well documented, it has yet to be determined whether there are sites in the transmembrane (TM) helices of CXCR4 important for HIV-1 and/or SDF-1α functions, and if such sites do exist, whether they are overlapping or distinctive for the separate functions of CXCR4. For this study, by employing alanine-scanning mutagenesis, 125I-SDF-1α competition binding, Ca2+ mobilization, and cell-cell fusion assays, we found that the mutation of many CXCR4 TM residues, including Tyr45, His79, Asp97, Pro163, Trp252, Tyr255, Asp262, Glu288, His294, and Asn298, could selectively decrease HIV-1-mediated cell fusion but not the binding activity of SDF-1α. Phe87 and Phe292, which were involved in SDF-1α binding, did not play a significant role in the coreceptor activity of CXCR4, further demonstrating the disconnection between physiological and pathological activities of CXCR4 TM domains. Our data also show that four mutations of the second extracellular loop, D182A, D187A, F189A, and P191A, could reduce HIV-1 entry without impairing either ligand binding or signaling. Taken together, our first detailed characterization of the different functional roles of CXCR4 TM domains may suggest a mechanistic basis for the discovery of new selective anti-HIV agents.

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“Hidden” dUTPase Sequence in Human Immunodeficiency Virus Type 1 gp120

Journal of Virology ◽

10.1128/jvi.73.1.751-753.1999 ◽

1999 ◽

Vol 73 (1) ◽

pp. 751-753 ◽

Cited By ~ 10

Author(s):

Chantal Abergel ◽

David L. Robertson ◽

Jean-Michel Claverie

Keyword(s):

Human Immunodeficiency Virus ◽

Human Immunodeficiency Virus Type ◽

Virus Type ◽

Equine Infectious Anemia Virus ◽

Sequence Similarity ◽

Coding Region ◽

Loop Region ◽

Immunodeficiency Virus ◽

Hiv 1

ABSTRACT A coding region homologous to the sequence for essential eukaryotic enzyme dUTPase has been identified in different genomic regions of several viral lineages. Unlike the nonprimate lentiviruses (caprine arthritis- encephalitis virus, equine infectious anemia virus, feline immunodeficiency virus, and visna virus), where dUTPase is integrated into the pol coding region, this enzyme has never been demonstrated to be present in the primate lentivirus genomes (human immunodeficiency virus type 1 [HIV-1], HIV-2, or the related simian immunodeficiency virus). A novel approach allowed us to identify a weak but significant sequence similarity between HIV-1 gp120 and the human dUTPase. This finding was then extended to all of the primate lentivirus lineages. Together with the recently reported fragmentary structural similarity between the V3 loop region and the Escherichia coli dUTPase (P. D. Kwong, R. Wyatt, J. Robinson, R. W. Sweet, J. Sodroski, and W. A. Hendrickson, Nature 393:648–659, 1998), our results strongly suggest that an ancestral dUTPase gene has evolved into the present primate lentivirus CD4 and cytokine receptor interacting region of gp120.

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