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Brown BK, Wieczorek L, Kijak G, Lombardi K, Currier J, Wesberry M, Kappes JC, Ngauy V, Marovich M, Michael N, Ochsenbauer C, Montefiori DC, Polonis VR. The role of natural killer (NK) cells and NK cell receptor polymorphisms in the assessment of HIV-1 neutralization. PLoS One 2012; 7:e29454. [PMID: 22509241 PMCID: PMC3324450 DOI: 10.1371/journal.pone.0029454] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2011] [Accepted: 11/29/2011] [Indexed: 11/18/2022] Open
Abstract
The importance of innate immune cells in HIV-1 pathogenesis and protection has been highlighted by the role of natural killer (NK) cells in the containment of viral replication. Use of peripheral blood mononuclear cells (PBMC) in immunologic studies provides both HIV-1 target cells (ie. CD4+ T cells), as well as anti-HIV-1 effector cells, such as NK cells. In this study, NK and other immune cell populations were analyzed in HIV-negative donor PBMC for an impact on the anti-HIV activity of polyclonal and monoclonal antibodies. NK cell percentages were significantly higher in donor PBMC that supported lower levels of viral replication. While the percentage of NK cells was not directly associated with neutralization titers, NK cell-depletion significantly diminished the antiviral antibody activity by up to three logs, and polymorphisms in NK killer immunoglobulin receptor (KIR) and FcγRIIIa alleles appear to be associated with this affect. These findings demonstrate that NK cells and NK cell receptor polymorphisms may influence assessment of traditional HIV-1 neutralization in a platform where antibody is continuously present. This format appears to simultaneously assess conventional entry inhibition (neutralization) and non-neutralizing antibody-dependent HIV inhibition, which may provide the opportunity to delineate the dominant antibody function(s) in polyclonal vaccine responses.
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MESH Headings
- Antibodies, Neutralizing/immunology
- Genotype
- HIV-1/immunology
- HIV-1/physiology
- Host-Pathogen Interactions
- Humans
- Killer Cells, Natural/immunology
- Killer Cells, Natural/metabolism
- Killer Cells, Natural/virology
- Leukocytes, Mononuclear/immunology
- Leukocytes, Mononuclear/virology
- Neutralization Tests
- Polymorphism, Genetic
- Receptors, IgG/genetics
- Receptors, KIR3DS1/genetics
- Receptors, Natural Killer Cell/genetics
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Affiliation(s)
- Bruce K. Brown
- Military HIV Research Program (MHRP), Rockville, Maryland, United States of America
- The Henry M. Jackson Foundation, Rockville, Maryland, United States of America
| | - Lindsay Wieczorek
- Military HIV Research Program (MHRP), Rockville, Maryland, United States of America
- The Henry M. Jackson Foundation, Rockville, Maryland, United States of America
| | - Gustavo Kijak
- Military HIV Research Program (MHRP), Rockville, Maryland, United States of America
- The Henry M. Jackson Foundation, Rockville, Maryland, United States of America
| | - Kara Lombardi
- Military HIV Research Program (MHRP), Rockville, Maryland, United States of America
- The Henry M. Jackson Foundation, Rockville, Maryland, United States of America
| | - Jeffrey Currier
- Military HIV Research Program (MHRP), Rockville, Maryland, United States of America
- The Henry M. Jackson Foundation, Rockville, Maryland, United States of America
| | - Maggie Wesberry
- Military HIV Research Program (MHRP), Rockville, Maryland, United States of America
- The Henry M. Jackson Foundation, Rockville, Maryland, United States of America
| | - John C. Kappes
- University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | - Viseth Ngauy
- Military HIV Research Program (MHRP), Rockville, Maryland, United States of America
- Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand
| | - Mary Marovich
- Military HIV Research Program (MHRP), Rockville, Maryland, United States of America
- Walter Reed Army Institute of Research, Rockville, Maryland, United States of America
| | - Nelson Michael
- Military HIV Research Program (MHRP), Rockville, Maryland, United States of America
- Walter Reed Army Institute of Research, Rockville, Maryland, United States of America
| | | | | | - Victoria R. Polonis
- Military HIV Research Program (MHRP), Rockville, Maryland, United States of America
- Walter Reed Army Institute of Research, Rockville, Maryland, United States of America
- * E-mail:
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Neutralization efficiency is greatly enhanced by bivalent binding of an antibody to epitopes in the V4 region and the membrane-proximal external region within one trimer of human immunodeficiency virus type 1 glycoproteins. J Virol 2010; 84:7114-23. [PMID: 20463081 DOI: 10.1128/jvi.00545-10] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Most antibodies are multivalent, with the potential to bind with high avidity. However, neutralizing antibodies commonly bind to virions monovalently. Bivalent binding of a monoclonal antibody (MAb) to a virion has been documented only in a single case. Thus, the role of high avidity in antibody-mediated neutralization of viruses has not been defined clearly. In this study, we demonstrated that when an artificial 2F5 epitope was inserted in the gp120 V4 region so that an HIV-1 envelope glycoprotein (Env) trimer contains a natural 2F5 epitope in the gp41 membrane-proximal envelope region (MPER) and an artificially engineered 2F5 epitope in the gp120 V4 region, bivalent 2F5 IgG achieved greatly enhanced neutralization efficiency, with a 50% inhibitory concentration (IC(50)) decrease over a 2-log scale. In contrast, the monovalent 2F5 Fab fragment did not exhibit any appreciable change in neutralization efficiency in the same context. These results demonstrate that bivalent binding of 2F5 IgG to a single HIV-1 Env trimer results in dramatic enhancement of neutralization, probably through an increase in binding avidity. Furthermore, we demonstrated that bivalent binding of MAb 2F5 to the V4 region and MPER of an HIV-1 Env trimer can be achieved only in a specific configuration, providing an important insight into the structure of a native/infectious HIV-1 Env trimer. This specific binding configuration also establishes a useful standard that can be applied to evaluate the biological relevance of structural information on the HIV-1 Env trimer.
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Abstract
PURPOSE OF REVIEW In this review we present current advances in our understanding of HIV-1 neutralization assays that employ primary cell types, as compared with those that utilize cell lines and the newer, more standardized pseudovirus assays. A commentary on the challenges of standardizing in-vitro neutralization assays using primary cells is included. RECENT FINDINGS The data from reporter cell line neutralization assays may agree with results observed in primary cells; however, exceptions have recently been reported. Multiple variables exist in primary cell assays using peripheral blood mononuclear cells from HIV-seronegative donors; in-vitro neutralization titers can vary significantly based on the donor cells used for assay targets and for virus propagation. Thus, more research is required to achieve validated primary cell neutralization assays. SUMMARY HIV-vaccine-induced antibody performance in the current neutralization assays may function as a 'gatekeeper' for HIV-1 subunit vaccine advancement. Development of standardized platforms for reproducible measurement of in-vitro neutralization is therefore a high priority. Given the considerable variation in results obtained from some widely applied HIV neutralization platforms, parallel evaluation of new antibodies using different host cells for assay targets, as well as virus propagation, is recommended until immune correlates of protection are identified.
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Zolla-Pazner S, Cohen S, Pinter A, Krachmarov C, Wrin T, Wang S, Lu S. Cross-clade neutralizing antibodies against HIV-1 induced in rabbits by focusing the immune response on a neutralizing epitope. Virology 2009; 392:82-93. [PMID: 19632700 DOI: 10.1016/j.virol.2009.05.039] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2009] [Revised: 05/18/2009] [Accepted: 05/28/2009] [Indexed: 11/17/2022]
Abstract
Studies were performed to induce cross-clade neutralizing antibodies (Abs) by testing various combinations of prime and boost constructs that focus the immune response on structurally-conserved epitopes in the V3 loop of HIV-1 gp120. Rabbits were immunized with gp120 DNA containing a V3 loop characterized by the GPGR motif at its tip, and/or with gp120 DNA with a V3 loop carrying the GPGQ motif. Priming was followed by boosts with V3-fusion proteins (V3-FPs) carrying the V3 sequence from a subtype B virus (GPGR motif), and/or with V3 sequences from subtypes A and C (GPGQ motif). The broadest and most consistent neutralizing responses were generated when using a clade C gp120 DNA prime and with the V3(B)-FP boost. Immune sera displayed neutralizing activity in three assays against pseudoviruses and primary isolates from subtypes A, AG, B, C, and D. Polyclonal Abs in the immune rabbit sera neutralized viruses that were not neutralized by pools of human anti-V3 monoclonal Abs. Greater than 80% of the neutralizing Abs were specific for V3, showing that the immune response could be focused on a neutralizing epitope and that vaccine-induced anti-V3 Abs have cross-clade neutralizing activity.
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Affiliation(s)
- Susan Zolla-Pazner
- New York University School of Medicine, 550 First Avenue, New York, NY, USA.
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Kittinunvorakoon C, Morris MK, Neeyapun K, Jetsawang B, Buehring GC, Hanson CV. Mother to child transmission of HIV-1 in a Thai population: role of virus characteristics and maternal humoral immune response. J Med Virol 2009; 81:768-78. [PMID: 19319941 DOI: 10.1002/jmv.21465] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The objective of this study was to investigate factors influencing mother to child transmission of HIV-1 in Thailand, where HIV-1 CRF01_AE, the major subtype in Southeast Asia, predominates. Samples from 84 HIV-1 infected, anti-retroviral treatment-naïve, non-breast feeding mothers, 28 who transmitted HIV-1 to their babies (transmitters) and 56 who did not (non-transmitters), were studied for maternal humoral immune response and virus characteristics. Maternal humoral immune response was measured by lymphocyte phenotyping; neutralizing antibodies to laboratory HIV-1 MN strain and two clinical isolates; peptide binding antibody to gp41 and V3 from strains CRF01_AE, B, and MN; autologous antibodies; and quasispecies diversity. Virus characteristics studied were viral load, co-receptor usage, and viral replication capacity. No significant difference between transmitters and non-transmitters was found for any parameter of maternal humoral immune response. However, viral load and viral replication capacity were significantly higher in transmitters versus non-transmitters and were not correlated with each other. This suggests that viral replication capacity may be a transmission factor independent of viral load, which is already well established as a risk factor for transmission of HIV-1. All except four viral isolates used the CCR5 co-receptor. This is one of few studies of vertical transmission in a population where HIV-1 CRF01_AE predominates. The data suggest that in this population the maternal humoral immune response was not important in preventing transmission at parturition, but that virus characteristics were key factors, and that viral replication capacity may contribute to birth-associated mother to child transmission of HIV-1.
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Affiliation(s)
- Chonticha Kittinunvorakoon
- Division of Infectious Diseases, School of Public Health, University of California, Berkeley, CA 94720-7354, USA
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Cross-clade neutralization patterns among HIV-1 strains from the six major clades of the pandemic evaluated and compared in two different models. Virology 2008; 375:529-38. [PMID: 18433824 DOI: 10.1016/j.virol.2008.02.022] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2007] [Revised: 12/28/2007] [Accepted: 02/11/2008] [Indexed: 11/23/2022]
Abstract
A panel of paired primary virus isolates and envelope pseudoviruses from sixty strains representing six HIV-1 clades was tested for neutralization using pooled, clade-specific plasma in two prominently utilized neutralization platforms: a primary isolate assay using peripheral blood mononuclear cells (PBMC) and a pseudovirus assay using a reporter epithelial cell line. Using the PMBC assay, pairing of the antibody pool against homologous clade viruses generated the highest geometric mean neutralizing antibody titer in 4 out of 6 clades tested, and neutralization patterns showed numerous examples of reciprocal cross-recognition between antibody and viruses of specific clade pairs. In the pseudovirus assay, cross-clade neutralization was more limited, with fewer distinct cross-clade relationships evident. The clade C antibody pool was broadly cross-reactive, neutralizing the greatest number of viruses in both assays. These data highlight the importance of the neutralization assay format employed and suggest that clade C envelopes merit further evaluation for the elicitation of broadly neutralizing antibodies.
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Polonis VR, Brown BK, Rosa Borges A, Zolla-Pazner S, Dimitrov DS, Zhang MY, Barnett SW, Ruprecht RM, Scarlatti G, Fenyö EM, Montefiori DC, McCutchan FE, Michael NL. Recent advances in the characterization of HIV-1 neutralization assays for standardized evaluation of the antibody response to infection and vaccination. Virology 2008; 375:315-20. [PMID: 18367229 DOI: 10.1016/j.virol.2008.02.007] [Citation(s) in RCA: 105] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2007] [Revised: 01/30/2008] [Accepted: 02/11/2008] [Indexed: 01/16/2023]
Abstract
In AIDS vaccine development the pendulum has swung towards a renewed emphasis on the potential role for neutralizing antibodies in a successful global vaccine. It is recognized that vaccine-induced antibody performance, as assessed in the available neutralization assays, may well serve as a "gatekeeper" for HIV-1 subunit vaccine prioritization and advancement. As a result, development of a standardized platform for reproducible measurement of neutralizing antibodies has received considerable attention. Here we review current advancements in our knowledge of the performance of different types of antibodies in a traditional primary cell neutralization assay and the newer, more standardized TZM-bl reporter cell line assay. In light of recently revealed differences (see accompanying article) in the results obtained in these two neutralization formats, parallel evaluation with both platforms should be contemplated as an interim solution until a better understanding of immune correlates of protection is achieved.
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Ying H, Ji X, Hart ML, Gupta K, Saifuddin M, Zariffard MR, Spear GT. Interaction of mannose-binding lectin with HIV type 1 is sufficient for virus opsonization but not neutralization. AIDS Res Hum Retroviruses 2004; 20:327-35. [PMID: 15117456 DOI: 10.1089/088922204322996563] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Mannose-binding lectin (MBL), a microbe-recognition protein in serum, binds to high mannose glycans on HIV-1 gp120 and has been reported to neutralize the cell line-adapted strain HIV(IIIB). Because HIV primary isolates (PI) are generally more resistant to neutralization by antibodies and considering that PI are produced in primary cells that could alter the number of high mannose glycans on HIV relative to cell lines, we assessed the ability to MBL to neutralize HIV PI. MBL at concentrations up to 50 microg/ml mediated relatively little neutralization (<20%) of HIV PI infection of peripheral blood mononuclear cells (PBMCs). MBL-neutralizing activity was slightly higher for cell line-adapted HIV infection of the H9 T cell line (up to 64% at 50 microg/ml). However, this effect was specific for H9 cells since MBL did not neutralize cell line-adapted virus infection of PBMCs, HIV PI infection of the GHOST cell line, or VSV pseudotyped with HIV gp160 from cell line-derived virus or PI. In contrast to its low activity in neutralization assays, MBL efficiently bound infectious HIV PI and opsonized HIV PI for uptake by monocytic cells. These results show that both PI and cell line-adapted HIV, despite binding of MBL, are relatively resistant to neutralization by levels of MBL normally present in serum. However, binding and opsonization of HIV by MBL may alter virus trafficking and viral-antigen presentation during HIV infection.
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Affiliation(s)
- Hongyu Ying
- Department of Immunology/Microbiology, Rush-Presbyterian-St. Luke's Medical Center, Chicago, Illinois 60612, USA
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Achkar JM, Wang XH, Nyambi P, Gorny MK, Zolla-Pazner S, Bandrés JC. Polymerase chain reaction-based assay for antibody-mediated neutralization of HIV-1 reveals a population of nonneutralized virus undetected by conventional p24 assay. J Acquir Immune Defic Syndr 2000; 24:203-10. [PMID: 10969343 DOI: 10.1097/00126334-200007010-00002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
To be successful with strategies involving passive immunization or the generation of neutralizing antibodies against HIV, it is crucial that we improve our understanding of the process of antibody-mediated HIV neutralization. We have used a neutralization assay based on polymerase chain reaction (PCR) that is more rapid and sensitive than the conventional p24 neutralization assay based on enzyme-linked immunosorbent assay (ELISA). PCR assays permit measurement of the number of infectious events and can detect small amounts of HIV-1 only a few days postinfection. In these studies, the human anti-V3 monoclonal antibody 694/98-D was used to neutralize the infectivity of the laboratory isolate HIVIIIB for CEM-SS cells. 8E5/LAV cells, which contain a single integrated copy of proviral DNA per cell, served as a standard to determine the amount of HIV-1 copies in infected CEM-SS cells. Evaluation of antibody-mediated neutralization was possible at 2 to 3 days postinfection, at a time when p24 readouts were not conclusive. We achieved >95% neutralization of HIVIIIB, and of its molecular clone HXB2, using the monoclonal antibody 694/98-D. This degree of neutralization is probably highly significant in vivo. Nevertheless, a small amount of both HIVIIIB and HXB2 ( approximately 5%) escapes neutralization and can consistently be detected after a few days by this sensitive assay. Experiments with different anti-HIV monoclonal antibodies and viruses showed that the assay could be applied to anti-V3 as well as anti-CD4 binding domain antibodies as well as HIV laboratory strains or primary isolates.
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Affiliation(s)
- J M Achkar
- New York Veterans Affairs Medical Center and Departments of Medicine and Pathology, New York University, New York City, New York 10010, USA
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Polymerase Chain Reaction–Based Assay for Antibody-Mediated Neutralization of HIV-1 Reveals a Population of Nonneutralized Virus Undetected by Conventional p24 Assay. J Acquir Immune Defic Syndr 2000. [DOI: 10.1097/00042560-200007010-00002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Cecilia D, KewalRamani VN, O'Leary J, Volsky B, Nyambi P, Burda S, Xu S, Littman DR, Zolla-Pazner S. Neutralization profiles of primary human immunodeficiency virus type 1 isolates in the context of coreceptor usage. J Virol 1998; 72:6988-96. [PMID: 9696790 PMCID: PMC109918 DOI: 10.1128/jvi.72.9.6988-6996.1998] [Citation(s) in RCA: 190] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Most strains of human immunodeficiency virus type 1 (HIV-1) which have only been carried in vitro in peripheral blood mononuclear cells (primary isolates) can be neutralized by antibodies, but their sensitivity to neutralization varies considerably. To study the parameters that contribute to the differential neutralization sensitivity of primary HIV-1 isolates, we developed a neutralization assay with a panel of genetically engineered cell lines (GHOST cells) that express CD4, one of eight chemokine receptors which function as HIV-1 coreceptors, and a Tat-dependent green fluorescent protein reporter cassette which permits the evaluation and quantitation of HIV-1 infection by flow cytometry. All 21 primary isolates from several clades could grow in the various GHOST cell lines, and their use of one or more coreceptors could easily be defined by flow cytometric analysis. Ten of these primary isolates, three that were CXCR4 (X4)-tropic, three that were CCR5 (R5)-tropic, and four that were dual- or polytropic were chosen for study of their sensitivity to neutralization by human monoclonal and polyclonal antibodies. Viruses from the X4-tropic category of viruses were first tested since they have generally been considered to be particularly neutralization sensitive. It was found that the X4-tropic virus group contained both neutralization-sensitive and neutralization-resistant viruses. Similar results were obtained with R5-tropic viruses and with dual- or polytropic viruses. Within each category of viruses, neutralization sensitivity and resistance could be observed. Therefore, sensitivity to neutralization appears to be the consequence of factors that influence the antibody-virus interaction and its sequelae rather than coreceptor usage. Neutralization of various viruses by the V3-specific monoclonal antibody, 447-52D, was shown to be dependent not only on the presence of the relevant epitope but also on its presentation. An epitope within the envelope of a particular virus is not sufficient to render a virus sensitive to neutralization by an antibody that recognizes that epitope. Moreover, conformation-dependent factors may overcome the need for absolute fidelity in the match between an antibody and its core epitope, permitting sufficient affinity between the viral envelope protein and the antibody to neutralize the virus. The studies indicate that the neutralization sensitivity of HIV-1 primary isolates is a consequence of the complex interaction between virus, antibody, and target cell.
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Affiliation(s)
- D Cecilia
- New York University Medical Center, New York, NY 10010, USA
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