Inhibition of HIV Env binding to cellular receptors by monoclonal antibody 2GI2 as probed by Fc-tagged gp120

National Institute for Communicable Diseases, Johannesburg, Gauteng, South Africa
Retrovirology (Impact Factor: 4.19). 02/2006; 3(1):39. DOI: 10.1186/1742-4690-3-39
Source: PubMed


During natural HIV infection, an array of host receptors are thought to influence virus attachment and the kinetics of infection. In this study, to probe the interactions of HIV envelope (Env) with various receptors, we assessed the inhibitory properties of various anti-Env monoclonal antibodies (mAbs) in binding assays. To assist in detecting Env in attachment assays, we generated Fc fusions of full-length wild-type gp120 and several variable loop-deleted gp120s. Through investigation of the inhibition of Env binding to cell lines expressing CD4, CCR5, DC-SIGN, syndecans or combinations thereof, we found that the broadly neutralizing mAb, 2G12, directed to a unique carbohydrate epitope of gp120, inhibited Env-CCR5 binding, partially inhibited Env-DC-SIGN binding, but had no effect on Env-syndecan association. Furthermore, 2G12 inhibited Env attachment to primary monocyte-derived dendritic cells, that expressed CD4 and CCR5 primary HIV receptors, as well as DC-SIGN, and suggested that the dual activities of 2G12 could be valuable in vivo for inhibiting initial virus dissemination and propagation.

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Available from: Udayan Chatterji, Mar 29, 2014
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    • "The DCs and virus were co-cultured at 37°C for 2 hours. For antibody inhibition assays, the virus was pre-incubated with 30 μg/mL monoclonal antibody (mAb) (anti-HIV-1 Env mAb 2 G12 [86], CH08 [40] or anti-Respiratory Syncytial Virus (RSV) mAb Syangis) for 30 minutes prior to co-culturing with the DCs. This concentration is similar to the concentration of total IgG in breast milk in this population (median 80 μg/ml range: 20 to 400 μg/ml [31]. "
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    ABSTRACT: Background Breastfeeding is a leading cause of infant HIV-1 infection in the developing world, yet only a minority of infants exposed to HIV-1 via breastfeeding become infected. As a genetic bottleneck severely restricts the number of postnatally-transmitted variants, genetic or phenotypic properties of the virus Envelope (Env) could be important for the establishment of infant infection. We examined the efficiency of virologic functions required for initiation of infection in the gastrointestinal tract and the neutralization sensitivity of HIV-1 Env variants isolated from milk of three postnatally-transmitting mothers (n=13 viruses), five clinically-matched nontransmitting mothers (n=16 viruses), and seven postnatally-infected infants (n = 7 postnatally-transmitted/founder (T/F) viruses). Results There was no difference in the efficiency of epithelial cell interactions between Env virus variants from the breast milk of transmitting and nontransmitting mothers. Moreover, there was similar efficiency of DC-mediated trans-infection, CCR5-usage, target cell fusion, and infectivity between HIV-1 Env-pseudoviruses from nontransmitting mothers and postnatal T/F viruses. Milk Env-pseudoviruses were generally sensitive to neutralization by autologous maternal plasma and resistant to breast milk neutralization. Infant T/F Env-pseudoviruses were equally sensitive to neutralization by broadly-neutralizing monoclonal and polyclonal antibodies as compared to nontransmitted breast milk Env variants. Conclusion Postnatally-T/F Env variants do not appear to possess a superior ability to interact with and cross a mucosal barrier or an exceptional resistance to neutralization that define their capability to initiate infection across the infant gastrointestinal tract in the setting of preexisting maternal antibodies.
    Full-text · Article · Jan 2013 · Retrovirology
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    • "We then tested the effect of sCD4 doses on HIV-1 infection (Bru-3, Bru-Yu2 and Mj4) and found that at 1 μg/ml or higher a concentration-dependent inhibition of HIV-1 infection by sCD4 was observed; while below 1 μg/ml no significant inhibition by sCD4 was observed (Zhou et al. data not shown). Thus, we chose sCD4 at the concentration of 0.3 μg/ml in the subsequent post-CD4 experiments as described before [43]. "
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    ABSTRACT: Identification of broad neutralization epitopes in HIV-1 envelope spikes is paramount for HIV-1 vaccine development. A few broad neutralization epitopes identified so far are present on the surface of native HIV-1 envelope spikes whose recognition by antibodies does not depend on conformational changes of the envelope spikes. However, HIV-1 envelope spikes also contain transiently-exposed neutralization epitopes, which are more difficult to identify. In this study, we constructed single chain Fvs (scFvs) derived from seven human monoclonal antibodies and genetically linked them with or without a glycosyl-phosphatidylinositol (GPI) attachment signal. We show that with a GPI attachment signal the scFvs are targeted to lipid rafts of plasma membranes. In addition, we demonstrate that four of the GPI-anchored scFvs, but not their secreted counterparts, neutralize HIV-1 with various degrees of breadth and potency. Among them, GPI-anchored scFv (X5) exhibits extremely potent and broad neutralization activity against multiple clades of HIV-1 strains tested. Moreover, we show that GPI-anchored scFv (4E10) also exhibited more potent neutralization activity than its secretory counterpart. Finally, we demonstrate that expression of GPI-anchored scFv (X5) in the lipid raft of plasma membrane of human CD4+ T cells confers long-term resistance to HIV-1 infection, HIV-1 envelope-mediated cell-cell fusion, and the infection of HIV-1 captured and transferred by human DCs. Thus GPI-anchored scFv could be used as a general and effective way to identify antibodies that react with transiently-exposed neutralization epitopes in envelope proteins of HIV-1 and other enveloped viruses. The GPI-anchored scFv (X5), because of its breadth and potency, should have a great potential to be developed into anti-viral agent for HIV-1 prevention and therapy.
    Full-text · Article · Oct 2010 · Retrovirology
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    • "The complexity of Env structure/ function and the allosteric nature of some forms of AI escape lead to the postulate that AI resistance could affect susceptibility to neutralizing antibodies or other classes of entry inhibitors (Ho et al., 2006; Kwong et al., 1998; Sanders et al., 2008; Wyatt et al., 1998). This hypothesis was tested using the broadly neutralizing antibodies 4E10 and 2F5 (Binley et al., 2006; Calarese et al., 2005; Nakowitsch et al., 2005; Zhang et al., 2004c; Zhou et al., 2007; Zwick et al., 2001, 2005), as well as the fusion inhibitor Enfuvirtide (Manfredi and Sabbatani, 2006; Wild et al., 1992) and the CXCR4 coreceptor inhibitor, AMD- 3100 (Khan et al., 2007; Schols et al., 1997). In this report, the effect of AI-resistant mutations on the sensitivity of virus to sera from HIV- Virology 402 (2010) 256–261 ⁎ Corresponding author. "
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    ABSTRACT: Treatment with HIV attachment inhibitors (AIs) can select for escape mutants throughout the viral envelope. We report on three such mutations: F423Y (gp120 CD4 binding pocket) and I595F and K655E (gp41 ectodomain). Each displayed decreased sensitivity to the AI BMS-488043 and earlier generation AIs, along with increased sensitivity to the broadly neutralizing antibodies 2F5 and 4E10, without affecting the rate of viral entry or sensitivity to the entry inhibitors AMD-3100 and Enfuvirtide. We also observed that I595F did not substantially increase envelope sensitivity to HIV-infected patient sera. Based on these observations, we propose that although F423Y, I595F and K655E may all affect the presentation of the 2F5 and 4E10 epitopes, natural immune mimicry is rare only for the I595F effect. Thus, it seems that in addition to restricting AI resistance development, incorporation of I595F into an appropriate vehicle could elicit a novel antiviral response to improve vaccine efficacy.
    Full-text · Article · Jul 2010 · Virology
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