1
|
Leong YA, Atnerkar A, Yu D. Human Immunodeficiency Virus Playing Hide-and-Seek: Understanding the T FH Cell Reservoir and Proposing Strategies to Overcome the Follicle Sanctuary. Front Immunol 2017; 8:622. [PMID: 28620380 PMCID: PMC5449969 DOI: 10.3389/fimmu.2017.00622] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Accepted: 05/10/2017] [Indexed: 12/20/2022] Open
Abstract
Human immunodeficiency virus (HIV) infects millions of people worldwide, and new cases continue to emerge. Once infected, the virus cannot be cleared by the immune system and causes acquired immunodeficiency syndrome. Combination antiretroviral therapeutic regimen effectively suppresses viral replication and halts disease progression. The treatment, however, does not eliminate the virus-infected cells, and interruption of treatment inevitably leads to viral rebound. The rebound virus originates from a group of virus-infected cells referred to as the cellular reservoir of HIV. Identifying and eliminating the HIV reservoir will prevent viral rebound and cure HIV infection. In this review, we focus on a recently discovered HIV reservoir in a subset of CD4+ T cells called the follicular helper T (TFH) cells. We describe the potential mechanisms for the emergence of reservoir in TFH cells, and the strategies to target and eliminate this viral reservoir.
Collapse
Affiliation(s)
- Yew Ann Leong
- Infection and Immunity Program, Department of Biochemistry and Molecular Biology, Monash Biomedicine Discovery Institute, Monash University, Clayton, VIC, Australia
| | - Anurag Atnerkar
- Infection and Immunity Program, Department of Biochemistry and Molecular Biology, Monash Biomedicine Discovery Institute, Monash University, Clayton, VIC, Australia
| | - Di Yu
- Infection and Immunity Program, Department of Biochemistry and Molecular Biology, Monash Biomedicine Discovery Institute, Monash University, Clayton, VIC, Australia.,Department of Immunology and Infectious Disease, John Curtin School of Medical Research, The Australian National University, Canberra, ACT, Australia
| |
Collapse
|
2
|
|
3
|
Yu X, Li Z, Zhou Z, Kilby JM, Jiang W. Microbial TLR Agonists and Humoral Immunopathogenesis in HIV Disease. EPIDEMIOLOGY (SUNNYVALE, CALIF.) 2013; 3:120. [PMID: 24795844 PMCID: PMC4005894 DOI: 10.4172/2161-1165.1000120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Although T cells are the primary and most-studied targets of the Human Immunodeficiency Virus (HIV), B cells, especially memory B lymphocytes, are also chronically depleted in the course of HIV disease. Although the lack of CD4+ T cell help may explain these deficiencies, intrinsic defects in B lymphocytes appear to contribute to B cell depletion and reduced antibody (Ab) production in the setting of HIV, especially of some antigens eliciting T cell-independent responses. The gut mucosal barrier is disrupted in HIV disease, resulting in increased systemic exposure to microbial products such as Toll-Like Receptor (TLR) agonists. The association of enhanced systemic levels of TLR agonists and B cell dysfunction in HIV disease is not understood. This review discusses the potential role of microbial TLR agonists in the B cell depletion, enhanced autoantibody production and impaired responses to vaccination observed in HIV-infected hosts. Increased microbial translocation in HIV infection may drive B cells to produce autoantibodies and increase susceptibilities of B cells to apoptosis through activation-induced cell death. Determining the mechanisms of B cell perturbations in HIV disease will inform the design of novel strategies of improve immune responses to vaccines, reduce opportunistic infections and slow disease progression.
Collapse
Affiliation(s)
- Xiaocong Yu
- Department of Medicine, Harvard Medical School, Boston, MA 02215, USA
| | - Zihai Li
- Department of Microbiology and Immunology, Department of Medicine, Division of Infectious Diseases, Medical University of South Carolina, BSB214E, Charleston, SC, 29425, USA
| | - Zhenxian Zhou
- NanJing Second Hospital, Infectious Diseases, NanJing, China
| | - J Michael Kilby
- Department of Microbiology and Immunology, Department of Medicine, Division of Infectious Diseases, Medical University of South Carolina, BSB214E, Charleston, SC, 29425, USA
| | - Wei Jiang
- Department of Microbiology and Immunology, Department of Medicine, Division of Infectious Diseases, Medical University of South Carolina, BSB214E, Charleston, SC, 29425, USA
| |
Collapse
|
4
|
|
5
|
Willey S, Aasa-Chapman MMI, O'Farrell S, Pellegrino P, Williams I, Weiss RA, Neil SJD. Extensive complement-dependent enhancement of HIV-1 by autologous non-neutralising antibodies at early stages of infection. Retrovirology 2011; 8:16. [PMID: 21401915 PMCID: PMC3065417 DOI: 10.1186/1742-4690-8-16] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2010] [Accepted: 03/14/2011] [Indexed: 01/24/2023] Open
Abstract
BACKGROUND Non-neutralising antibodies to the envelope glycoprotein are elicited during acute HIV-1 infection and are abundant throughout the course of disease progression. Although these antibodies appear to have negligible effects on HIV-1 infection when assayed in standard neutralisation assays, they have the potential to exert either inhibitory or enhancing effects through interactions with complement and/or Fc receptors. Here we report that non-neutralising antibodies produced early in response to HIV-1 infection can enhance viral infectivity. RESULTS We investigated this complement-mediated antibody-dependent enhancement (C'-ADE) of early HIV infection by carrying out longitudinal studies with primary viruses and autologous sera derived sequentially from recently infected individuals, using a T cell line naturally expressing the complement receptor 2 (CR2; CD21). The C'-ADE was consistently observed and in some cases achieved infection-enhancing levels of greater than 350-fold, converting a low-level infection to a highly destructive one. C'-ADE activity declined as a neutralising response to the early virus emerged, but later virus isolates that had escaped the neutralising response demonstrated an increased capacity for enhanced infection by autologous antibodies. Moreover, sera with autologous enhancing activity were capable of C'ADE of heterologous viral isolates, suggesting the targeting of conserved epitopes on the envelope glycoprotein. Ectopic expression of CR2 on cell lines expressing HIV-1 receptors was sufficient to render them sensitive to C'ADE. CONCLUSIONS Taken together, these results suggest that non-neutralising antibodies to the HIV-1 envelope that arise during acute infection are not 'passive', but in concert with complement and complement receptors may have consequences for HIV-1 dissemination and pathogenesis.
Collapse
Affiliation(s)
- Suzanne Willey
- MRC/UCL Centre for Medical Molecular Virology, Division of Infection and Immunity, University College London, 46 Cleveland Street, London W1T 4JF, UK
- Department of Infectious Diseases, King's College London, Peter Gorer Department of Immunobiology, Borough Wing, Guy's Hospital, London SE1 9RT, UK
| | - Marlén MI Aasa-Chapman
- MRC/UCL Centre for Medical Molecular Virology, Division of Infection and Immunity, University College London, 46 Cleveland Street, London W1T 4JF, UK
| | - Stephen O'Farrell
- Centre for Sexual Health and HIV Research, University College London, UK
| | - Pierre Pellegrino
- Centre for Sexual Health and HIV Research, University College London, UK
| | - Ian Williams
- Centre for Sexual Health and HIV Research, University College London, UK
| | - Robin A Weiss
- MRC/UCL Centre for Medical Molecular Virology, Division of Infection and Immunity, University College London, 46 Cleveland Street, London W1T 4JF, UK
| | - Stuart JD Neil
- MRC/UCL Centre for Medical Molecular Virology, Division of Infection and Immunity, University College London, 46 Cleveland Street, London W1T 4JF, UK
- Department of Infectious Diseases, King's College London, Peter Gorer Department of Immunobiology, Borough Wing, Guy's Hospital, London SE1 9RT, UK
| |
Collapse
|
6
|
Xu Y, Zhang C, Jia L, Wen C, Liu H, Wang Y, Sun Y, Huang L, Zhou Y, Song H. A novel approach to inhibit HIV-1 infection and enhance lysis of HIV by a targeted activator of complement. Virol J 2009; 6:123. [PMID: 19671191 PMCID: PMC3224960 DOI: 10.1186/1743-422x-6-123] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2009] [Accepted: 08/12/2009] [Indexed: 02/02/2023] Open
Abstract
Background The complement system is one of the most potent weapons of innate immunity. It is not only a mechanism for direct protection against invading pathogens but it also interacts with the adaptive immunity to optimize the pathogen-specific humoral and cellular defense cascades in the body. Complement-mediated lysis of HIV is inefficient but the presence of HIV particles results in complement activation by the generation of many C3-fragments, such as C3dg and C3d. It has been demonstrated that activation of complement can enhance HIV infection through the binding of special complement receptor type 2 expression on the surface of mature B cells and follicular dendritic cells. Presentation of the hypothesis Previous studies have proven that the complement-mediated antibody-dependent enhancement of HIV infection is mediated by the association of complement receptor type 2 bound to the C3 fragment and deposited on the surface of HIV virions. Thus, we hypothesize that a new activator of complement, consisting of a target domain (C3-binding region of complement receptor type 2) linked to a complement-activating human IgG1 Fc domain (CR2-Fc), can target and amplify complement deposition on HIV virions and enhance the efficiency of HIV lysis. Testing the hypothesis Our hypothesis was tested using cell-free HIV-1 virions cultivated in vitro and assessment of virus opsonization was performed by incubating appropriate dilutions of virus with medium containing normal human serum and purified CR2-Fc proteins. As a control group, viruses were incubated with normal human serum under the same conditions. Virus neutralization assays were used to estimate the degree of CR2-Fc-enhanced lysis of HIV compared to untreated virus. Implications of the hypothesis The targeted complement activator, CR2-Fc, can be used as a novel approach to HIV therapy by abrogating the complement-enhanced HIV infection of cells.
Collapse
Affiliation(s)
- Yuanyong Xu
- Institute of Disease Control and Prevention, Academy of Military Medical Science, Beijing, PR China.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
7
|
Falkensammer B, Rubner B, Hiltgartner A, Wilflingseder D, Stahl Hennig C, Kuate S, Uberla K, Norley S, Strasak A, Racz P, Stoiber H. Role of complement and antibodies in controlling infection with pathogenic simian immunodeficiency virus (SIV) in macaques vaccinated with replication-deficient viral vectors. Retrovirology 2009; 6:60. [PMID: 19545395 PMCID: PMC2713197 DOI: 10.1186/1742-4690-6-60] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2009] [Accepted: 06/21/2009] [Indexed: 01/13/2023] Open
Abstract
Background We investigated the interplay between complement and antibodies upon priming with single-cycle replicating viral vectors (SCIV) encoding SIV antigens combined with Adeno5-SIV or SCIV pseudotyped with murine leukemia virus envelope boosting strategies. The vaccine was applied via spray-immunization to the tonsils of rhesus macaques and compared with systemic regimens. Results Independent of the application regimen or route, viral loads were significantly reduced after challenge with SIVmac239 (p < 0.03) compared to controls. Considerable amounts of neutralizing antibodies were induced in systemic immunized monkeys. Most of the sera harvested during peak viremia exhibited a trend with an inverse correlation between complement C3-deposition on viral particles and plasma viral load within the different vaccination groups. In contrast, the amount of the observed complement-mediated lysis did not correlate with the reduction of SIV titres. Conclusion The heterologous prime-boost strategy with replication-deficient viral vectors administered exclusively via the tonsils did not induce any neutralizing antibodies before challenge. However, after challenge, comparable SIV-specific humoral immune responses were observed in all vaccinated animals. Immunization with single cycle immunodeficiency viruses mounts humoral immune responses comparable to live-attenuated immunodeficiency virus vaccines.
Collapse
Affiliation(s)
- Barbara Falkensammer
- Department of Hygiene, Microbiology and Social Medicine, Innsbruck Medical University, 6020 Innsbruck, Austria.
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
8
|
Avirutnan P, Mehlhop E, Diamond MS. Complement and its role in protection and pathogenesis of flavivirus infections. Vaccine 2009; 26 Suppl 8:I100-7. [PMID: 19388173 PMCID: PMC2768071 DOI: 10.1016/j.vaccine.2008.11.061] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The complement system is a family of serum and cell surface proteins that recognize pathogen-associated molecular patterns, altered-self ligands, and immune complexes. Activation of the complement cascade triggers several antiviral functions including pathogen opsonization and/or lysis, and priming of adaptive immune responses. In this review, we will examine the role of complement activation in protection and/or pathogenesis against infection by Flaviviruses, with an emphasis on experiments with West Nile and Dengue viruses.
Collapse
Affiliation(s)
- Panisadee Avirutnan
- Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, United States
| | | | | |
Collapse
|
9
|
Willey S, Aasa-Chapman MMI. Humoral immunity to HIV-1: neutralisation and antibody effector functions. Trends Microbiol 2008; 16:596-604. [PMID: 18964020 DOI: 10.1016/j.tim.2008.08.008] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2008] [Revised: 08/04/2008] [Accepted: 08/21/2008] [Indexed: 10/21/2022]
Abstract
Several features of HIV have frustrated efforts to develop a vaccine able to induce broadly neutralising antibodies. The enormous genetic diversity of HIV is a major factor, accompanied by the camouflaged nature of the envelope spike, upon which HIV depends for cellular entry and to which antibodies must bind to neutralise. The picture is further complicated by the presence of nonfunctional envelope glycoproteins on the surface of HIV that are immunogenic. Consequently, HIV attracts antibodies that do not directly neutralise the virus but still activate complement and engage Fc receptors, which can both enhance and inhibit infection. The various effects that anti-envelope antibodies have on HIV infection will be reviewed here. Further research is needed to determine if these in vitro-characterised activities have relevance in vivo, and if some of the undesirable effects of non-neutralising antibodies can be avoided or the beneficial effects harnessed.
Collapse
Affiliation(s)
- Suzanne Willey
- MRC/UCL Centre for Medical Molecular Virology, Division of Infection and Immunity, University College London, 46 Cleveland Street, London W1T 4JF, UK
| | | |
Collapse
|
10
|
Complement-HIV interactions during all steps of viral pathogenesis. Vaccine 2007; 26:3046-54. [PMID: 18191309 DOI: 10.1016/j.vaccine.2007.12.003] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2007] [Revised: 11/27/2007] [Accepted: 12/01/2007] [Indexed: 01/24/2023]
Abstract
Upon crossing the endothelial barrier of the host, HIV initiates immediate responses of the immunity system. Among its components, the complement system is one of the first the first elements, which are activated to affect HIV propagation. Complement participates not only in the early phase of the immune response, but its effects can be observed continuously and also concern the induction and modification of the adaptive immune response. Here we discuss the role of complement in early and late stages of HIV pathogenesis and review the escape mechanisms, which protect HIV from destruction by the complement system.
Collapse
|
11
|
Wilflingseder D, Banki Z, Garcia E, Pruenster M, Pfister G, Muellauer B, Nikolic DS, Gassner C, Ammann CG, Dierich MP, Piguet V, Stoiber H. IgG opsonization of HIV impedes provirus formation in and infection of dendritic cells and subsequent long-term transfer to T cells. THE JOURNAL OF IMMUNOLOGY 2007; 178:7840-8. [PMID: 17548622 DOI: 10.4049/jimmunol.178.12.7840] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Already at initial phases of infection, HIV is coated with complement fragments. During the chronic phase, when HIV-specific IgGs appear, the virus circulates immune complexed with IgG and complement. Thus, we studied the interaction of dendritic cells (DCs) and DC-T cell cocultures with complement (C)-opsonized and C-IgG-opsonized HIV. HIV infection of monocyte-derived DCs and circulating BDCA-1-positive DCs was significantly reduced upon the presence of virus-specific but non-neutralizing IgGs. DCs exposed to C-Ig-HIV or IgG-opsonized HIV showed an impaired provirus formation and p24 production and a decreased transmission rate to autologous nonstimulated T cells upon migration along a chemokine gradient. This reduced infectivity was also observed in long-term experiments, when T cells were added delayed to DCs exposed to IgG-coated HIV without migration. Similar kinetics were seen when sera from HIV-1-infected individuals before and after seroconversion were used in infection assays. Both C- and C-IgG-opsonized HIV were captured and targeted to a tetraspanin-rich endosome in immature DCs, but differed with respect to MHC class II colocalization. The reduced infection by IgG-opsonized HIV is possibly due to interactions of virus-bound IgG with FcgammaRIIb expressed on DCs. Therefore, the intracellular fate and transmission of immune-complexed HIV seems to differ depending on time and opsonization pattern.
Collapse
Affiliation(s)
- Doris Wilflingseder
- Department of Hygiene, Microbiology and Social Medicine, Innsbruck Medical University, Innsbruck, Austria.
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
12
|
Robinson WE. Mechanism for complement-mediated, antibody-dependent enhancement of human immunodeficiency virus type 1 infection in MT2 cells is enhanced entry through CD4, CD21, and CXCR4 chemokine receptors. Viral Immunol 2006; 19:434-47. [PMID: 16987062 DOI: 10.1089/vim.2006.19.434] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Some antibodies neutralize Human Immunodeficiency Virus (HIV). However, antibody to HIV and complement can enhance HIV replication if cells express both complement receptors and CD4, a phenomenon described as complement-mediated, antibody-dependent enhancement (C'ADE). Although increased binding of opsonized virions has been reported, the mechanism by which C'ADE enhances HIV replication remains unproven. In this study, real-time polymerase chain reaction to detect HIV cDNA indicates that complement and anti-HIV antibodies enhance HIV entry 8- to 30- fold with similar increases in integrated provirus. Thus, complement increases HIV replication through a mechanism of enhanced entry. To further refine the mechanism of C'ADE, chemokine receptor antagonists were employed. JM2987, a CXCR4 chemokine receptor antagonist, blocked HIV infection and C'ADE; thus CD4, complement receptors, and CXCR4 chemokine receptors are required for enhanced entry of HIV into MT2 cells. Finally, anti-HIV immunoglobulin enhanced replication of not only group M clade B HIV but also group M clade D and group O isolates. These data demonstrate that antibodies mediating C'ADE of HIV infection are broadly reactive.
Collapse
Affiliation(s)
- W Edward Robinson
- Department of Pathology, University of California, Irvine, CA 92697-4800, USA.
| |
Collapse
|
13
|
Viau M, Veas F, Zouali M. Direct impact of inactivated HIV-1 virions on B lymphocyte subsets. Mol Immunol 2006; 44:2124-34. [PMID: 17134757 DOI: 10.1016/j.molimm.2006.07.302] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2006] [Revised: 07/04/2006] [Accepted: 07/10/2006] [Indexed: 11/26/2022]
Abstract
Although there is no convincing evidence that HIV infects primary B cells, marked changes in B cell responses have been described in HIV-1-infected subjects, including B cell repertoire perturbations, depression of B cell memory and paucity of CD5(+) B cells. As it is hard to assess the consequences of these in vitro and ex vivo observations in patients, the pathogenic mechanisms responsible for the B cell deficit are unclear, and direct and indirect effects of HIV-1 remain possible. To gain further insight into the impact of HIV-1 on the B cell compartment in vivo, we used XenoMouse mice, mice genetically engineered to express human antibodies with an absence of mouse antibody expression. In these transgenic animals, B cells expressing a virtually full human Ig repertoire develop, which allows investigation of the in vivo consequences of confronting B cells expressing human immunoglobulins with HIV-1. We found that soluble gp120 induced an inversion in the B-1a/B-1b cell ratios, without impacting B-2 cells or affecting substantially the T cell compartment. Virion treatment specifically and dramatically depressed B-1a cells, which represent the majority of B-1 cells in normal mice. The observed B cell changes were associated with a functional alteration of the humoral response to tetanus toxoid. Thus, the results reveal a capacity of HIV-1 to specifically impact a highly specialized B cell subpopulation. Because there is evidence that human IgM memory B cells are functionally equivalent to murine B-1a cells, our findings suggest that gp120 may have a direct deleting activity on B cell memory.
Collapse
|
14
|
Bánki Z, Wilflingseder D, Ammann CG, Pruenster M, Müllauer B, Holländer K, Meyer M, Sprinzl GM, van Lunzen J, Stellbrink HJ, Dierich MP, Stoiber H. Factor I-mediated processing of complement fragments on HIV immune complexes targets HIV to CR2-expressing B cells and facilitates B cell-mediated transmission of opsonized HIV to T cells. THE JOURNAL OF IMMUNOLOGY 2006; 177:3469-76. [PMID: 16920989 DOI: 10.4049/jimmunol.177.5.3469] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Our study demonstrates that binding of complement-opsonized HIV to complement receptor type 1 on human erythrocytes (E) via C3b fragments is followed by a rapid normal human serum-mediated detachment of HIV from E. The release was dependent on the presence of factor I indicating a conversion of C3b fragments to iC3b and C3d on the viral surface. This in turn resulted in an efficient binding of opsonized HIV to CR2-expressing B cells, thus facilitating B cell-mediated transmission of HIV to T cells. These data provide a new dynamic view of complement opsonization of HIV, suggesting that association of virus with E might be a transient phenomenon and the factor I-mediated processing of C3b to iC3b and C3d on HIV targets the virus to complement receptor type 2-expressing cells. Thus, factor I in concert with CR1 on E and factor H in serum due to their cofactor activity are likely to be important contributors for the generation of C3d-opsonized infectious HIV reservoirs on follicular dendritic cells and/or B cells in HIV-infected individuals.
Collapse
Affiliation(s)
- Zoltán Bánki
- Department of Hygiene, Microbiology and Social Medicine, Innsbruck Medical University, Austria.
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
15
|
Stoiber H, Pruenster M, Ammann CG, Dierich MP. Complement-opsonized HIV: the free rider on its way to infection. Mol Immunol 2005; 42:153-60. [PMID: 15488605 DOI: 10.1016/j.molimm.2004.06.024] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The complement system (C) is one of the main humoral components of innate immunity. Three major tasks of C against invading pathogens are: (i) lysis of pathogens by the formation of the membrane attack complex (MAC); (ii) opsonization of pathogens with complement fragments to favor phagocytosis; and (iii) attraction of inflammatory cells by chemotaxis. Like other particles, HIV activates C and becomes opsonized. To escape complement-mediated lysis, HIV has adopted various properties, which include the acquisition of HIV-associated molecules (HAMs) belonging to the family of complement regulators, such as CD46, CD55, CD59, and the interaction with humoral regulatory factors like factor H (fH). Opsonized virus may bind to complement receptor positive cells to infect them more efficiently or to remain bound on the surface of such cells. In the latter case HIV can be transmitted to cells susceptible for infection. This review discusses several aspects of C-HIV interactions and provides a model for the dynamics of this process.
Collapse
Affiliation(s)
- Heribert Stoiber
- Institute of Hygiene and Social Medicine, Innsbruck Medical University, Fritz-Pregl-Strasse 3, 6020 Innsbruck, Austria.
| | | | | | | |
Collapse
|
16
|
Bánki Z, Stoiber H, Dierich MP. HIV and human complement: inefficient virolysis and effective adherence. Immunol Lett 2004; 97:209-14. [PMID: 15752560 DOI: 10.1016/j.imlet.2004.11.007] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2004] [Revised: 11/08/2004] [Accepted: 11/08/2004] [Indexed: 02/02/2023]
Abstract
Both, HIV envelope proteins gp120 and gp41 can directly activate complement system, even in the absence of HIV-specific antibodies. During the budding process HIV acquires host membrane-associated molecules among these complement regulatory proteins (CRPs). The presence of CRPs on the viral surface rescues HIV from complement-mediated virolysis. The inefficient virolysis results in the deposition of complement-fragments on the viral surface allowing interactions of HIV with complement receptor expressing cells. In this review, the interaction of HIV with the complement system and the consequences of complement opsonisation on virus infection will be discussed.
Collapse
Affiliation(s)
- Zoltán Bánki
- Department of Hygiene, Microbiology and Social Medicine, Division of Hygiene and Medical Microbiology, Innsbruck Medical University, Innsbruck, Austria and Ludwig-Boltzmann-Institute for AIDS research, Fritz-Pregl-Str. 3., 6020 Innsbruck, Austria
| | | | | |
Collapse
|
17
|
Stoiber H, Speth C, Dierich MP. Role of complement in the control of HIV dynamics and pathogenesis. Vaccine 2003; 21 Suppl 2:S77-82. [PMID: 12763687 DOI: 10.1016/s0264-410x(03)00203-2] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
In all ex vivo preparations of HIV tested so far, C3 fragments and, after seroconversion, antibodies were detected on the viral surface. This indicates that HIV survives complement-mediated lysis. The virus has adopted different protection mechanisms to keep complement activation under the threshold necessary to induce virolysis. Among them are complement regulatory proteins that remain functionally active on the surface of HIV and turn down the complement cascade and serum proteins with complement regulatory activities. Therefore, opsonized virions accumulate in HIV-infected individuals, and subsequently adhere to complement receptor (CR) expressing cells. Among them are B cells, which bind opsonized virus. Such bound virus is efficiently transferred to autologous T cells, which subsequently are infected. Other cells interacting via CR with opsonized HIV are follicular dendritic cells (FDC). As shown by ex vivo experiments, up to 80% of virus is bound to follicular dendritic cells through C3-CR interactions. In the brain, HIV is not only interacting with complement proteins, but is able to induce their expression. Thus, interaction of HIV with the complement system is a main mechanism for pathogenesis to AIDS, since retention of (complement-resistant) opsonized viral particles on cell surfaces via CRs occurs in different compartments in HIV-infected individuals, thereby promoting transmission of virus to other permissive cells.
Collapse
Affiliation(s)
- Heribert Stoiber
- Institute of Hygiene and Social Medicine and Ludwig Boltzmann Institute for AIDS Research, University Innsbruck, Fritz Pregl-Strasse 3, A-6020 Innsbruck, Austria.
| | | | | |
Collapse
|
18
|
Affiliation(s)
- F P Siegal
- St. Vincents Hospital Medical Center, New York, New York, USA
| | | |
Collapse
|
19
|
Hlavacek WS, Percus JK, Percus OE, Perelson AS, Wofsy C. Retention of antigen on follicular dendritic cells and B lymphocytes through complement-mediated multivalent ligand-receptor interactions: theory and application to HIV treatment. Math Biosci 2002; 176:185-202. [PMID: 11916508 DOI: 10.1016/s0025-5564(02)00091-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
In HIV-infected patients, large quantities of HIV are associated with follicular dendritic cells (FDCs) in lymphoid tissue. During antiretroviral therapy, most of this virus disappears after six months of treatment, suggesting that FDC-associated virus has little influence on the eventual outcome of long-term therapy. However, a recent theoretical study using a stochastic model for the interaction of HIV with FDCs indicated that some virus may be retained on FDCs for years, where it can potentially reignite infection if treatment is interrupted. In that study, an approximate expression was used to estimate the time an individual virion remains on FDCs during therapy. Here, we determine the conditions under which this approximation is valid, and we develop expressions for the time a virion spends in any bound state and for the effect of rebinding on retention. We find that rebinding, which is influenced by diffusion, may play a major role in retention of HIV on FDCs. We also consider the possibility that HIV is retained on B cells during therapy, which like FDCs also interact with HIV. We find that virus associated with B cells is unlikely to persist during therapy.
Collapse
Affiliation(s)
- William S Hlavacek
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA.
| | | | | | | | | |
Collapse
|