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Muniraju M, Mutsvunguma LZ, Reidel IG, Escalante GM, Cua S, Musonda W, Calero-Landa J, Farelo MA, Rodriguez E, Li Z, Ogembo JG. Kaposi sarcoma-associated herpesvirus complement control protein (KCP) and glycoprotein K8.1 are not required for viral infection in vitro or in vivo. J Virol 2024; 98:e0057624. [PMID: 38767375 DOI: 10.1128/jvi.00576-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2024] [Accepted: 04/21/2024] [Indexed: 05/22/2024] Open
Abstract
Kaposi sarcoma-associated herpesvirus (KSHV), also known as human herpesvirus-8, is the causal agent of Kaposi sarcoma, a cancer that appears as tumors on the skin or mucosal surfaces, as well as primary effusion lymphoma and KSHV-associated multicentric Castleman disease, which are B-cell lymphoproliferative disorders. Effective prophylactic and therapeutic strategies against KSHV infection and its associated diseases are needed. To develop these strategies, it is crucial to identify and target viral glycoproteins involved in KSHV infection of host cells. Multiple KSHV glycoproteins expressed on the viral envelope are thought to play a pivotal role in viral infection, but the infection mechanisms involving these glycoproteins remain largely unknown. We investigated the role of two KSHV envelope glycoproteins, KSHV complement control protein (KCP) and K8.1, in viral infection in various cell types in vitro and in vivo. Using our newly generated anti-KCP antibodies, previously characterized anti-K8.1 antibodies, and recombinant mutant KSHV viruses lacking KCP, K8.1, or both, we demonstrated the presence of KCP and K8.1 on the surface of both virions and KSHV-infected cells. We showed that KSHV lacking KCP and/or K8.1 remained infectious in KSHV-susceptible cell lines, including epithelial, endothelial, and fibroblast, when compared to wild-type recombinant KSHV. We also provide the first evidence that KSHV lacking K8.1 or both KCP and K8.1 can infect human B cells in vivo in a humanized mouse model. Thus, these results suggest that neither KCP nor K8.1 is required for KSHV infection of various host cell types and that these glycoproteins do not determine KSHV cell tropism. IMPORTANCE Kaposi sarcoma-associated herpesvirus (KSHV) is an oncogenic human gamma-herpesvirus associated with the endothelial malignancy Kaposi sarcoma and the lymphoproliferative disorders primary effusion lymphoma and multicentric Castleman disease. Determining how KSHV glycoproteins such as complement control protein (KCP) and K8.1 contribute to the establishment, persistence, and transmission of viral infection will be key for developing effective anti-viral vaccines and therapies to prevent and treat KSHV infection and KSHV-associated diseases. Using newly generated anti-KCP antibodies, previously characterized anti-K8.1 antibodies, and recombinant mutant KSHV viruses lacking KCP and/or K8.1, we show that KCP and K8.1 can be found on the surface of both virions and KSHV-infected cells. Furthermore, we show that KSHV lacking KCP and/or K8.1 remains infectious to diverse cell types susceptible to KSHV in vitro and to human B cells in vivo in a humanized mouse model, thus providing evidence that these viral glycoproteins are not required for KSHV infection.
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Affiliation(s)
- Murali Muniraju
- Department of Immuno-Oncology, Beckman Research Institute of City of Hope, Duarte, California, USA
| | - Lorraine Z Mutsvunguma
- Department of Immuno-Oncology, Beckman Research Institute of City of Hope, Duarte, California, USA
| | - Ivana G Reidel
- Department of Immuno-Oncology, Beckman Research Institute of City of Hope, Duarte, California, USA
| | - Gabriela M Escalante
- Department of Immuno-Oncology, Beckman Research Institute of City of Hope, Duarte, California, USA
| | - Simeon Cua
- Department of Immuno-Oncology, Beckman Research Institute of City of Hope, Duarte, California, USA
| | - Webster Musonda
- Department of Immuno-Oncology, Beckman Research Institute of City of Hope, Duarte, California, USA
| | - Jonathan Calero-Landa
- Department of Immuno-Oncology, Beckman Research Institute of City of Hope, Duarte, California, USA
- Irell & Manella Graduate School of Biological Sciences of City of Hope, Duarte, California, USA
| | - Mafalda A Farelo
- Department of Immuno-Oncology, Beckman Research Institute of City of Hope, Duarte, California, USA
| | - Esther Rodriguez
- Department of Immuno-Oncology, Beckman Research Institute of City of Hope, Duarte, California, USA
- Irell & Manella Graduate School of Biological Sciences of City of Hope, Duarte, California, USA
| | - Zhou Li
- Department of Molecular and Cellular Biology, Beckman Research Institute of City of Hope, Duarte, California, USA
| | - Javier Gordon Ogembo
- Department of Immuno-Oncology, Beckman Research Institute of City of Hope, Duarte, California, USA
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Heggi MT, Nour El-Din HT, Morsy DI, Abdelaziz NI, Attia AS. Microbial evasion of the complement system: a continuous and evolving story. Front Immunol 2024; 14:1281096. [PMID: 38239357 PMCID: PMC10794618 DOI: 10.3389/fimmu.2023.1281096] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Accepted: 11/30/2023] [Indexed: 01/22/2024] Open
Abstract
The complement system is a fundamental part of the innate immune system that plays a key role in the battle of the human body against invading pathogens. Through its three pathways, represented by the classical, alternative, and lectin pathways, the complement system forms a tightly regulated network of soluble proteins, membrane-expressed receptors, and regulators with versatile protective and killing mechanisms. However, ingenious pathogens have developed strategies over the years to protect themselves from this complex part of the immune system. This review briefly discusses the sequence of the complement activation pathways. Then, we present a comprehensive updated overview of how the major four pathogenic groups, namely, bacteria, viruses, fungi, and parasites, control, modulate, and block the complement attacks at different steps of the complement cascade. We shed more light on the ability of those pathogens to deploy more than one mechanism to tackle the complement system in their path to establish infection within the human host.
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Affiliation(s)
- Mariam T. Heggi
- Clinical Pharmacy Undergraduate Program, Faculty of Pharmacy, Cairo University, Cairo, Egypt
| | - Hanzada T. Nour El-Din
- Department of Microbiology and Immunology, Faculty of Pharmacy, Cairo University, Cairo, Egypt
| | | | | | - Ahmed S. Attia
- Department of Microbiology and Immunology, Faculty of Pharmacy, Cairo University, Cairo, Egypt
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3
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Barrett L, Dai L, Wang S, Qin Z. Kaposi's sarcoma-associated herpesvirus and extracellular vesicles. J Med Virol 2021; 93:3294-3299. [PMID: 33415746 DOI: 10.1002/jmv.26780] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Revised: 01/04/2021] [Accepted: 01/05/2021] [Indexed: 01/13/2023]
Abstract
Kaposi's sarcoma-associated herpesvirus (KSHV) represents the etiological agent for several human malignancies, including Kaposi's Sarcoma (KS), primary effusion lymphoma (PEL), and multicentric Castleman's disease (MCD), which develop mainly in immunocompromised patients. KSHV has established many strategies to hijack and thwart the host's immune responses, including through the use of extracellular vesicles (EVs). EVs represent a significant mode of intercellular communication as they carry a variety of molecules that can be delivered from cell-to-cell. EVs are now recognized as one of the major players in immune system development and function during both innate and adaptive immune responses. In the current mini-review, we summarize recent findings on how KSHV utilizes EVs to create favorable environments for viral spread and persistence while evading immune responses. We also discuss the limitations and unanswered questions in this field and the potential areas for related immunotherapies.
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Affiliation(s)
- Lindsey Barrett
- Department of Pathology, Winthrop P. Rockefeller Cancer Institute, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Lu Dai
- Department of Pathology, Winthrop P. Rockefeller Cancer Institute, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Shanzhi Wang
- Department of Chemistry, University of Arkansas at Little Rock, Little Rock, Arkansas, USA
| | - Zhiqiang Qin
- Department of Pathology, Winthrop P. Rockefeller Cancer Institute, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
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4
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Parr YA, Beall MJ, Levy JK, McDonald M, Hamman NT, Willett BJ, Hosie MJ. Measuring the Humoral Immune Response in Cats Exposed to Feline Leukaemia Virus. Viruses 2021; 13:v13030428. [PMID: 33800090 PMCID: PMC7998633 DOI: 10.3390/v13030428] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Revised: 02/23/2021] [Accepted: 03/05/2021] [Indexed: 01/18/2023] Open
Abstract
Retroviruses belong to an important and diverse family of RNA viruses capable of causing neoplastic disease in their hosts. Feline leukaemia virus (FeLV) is a gammaretrovirus that infects domestic and wild cats, causing immunodeficiency, cytopenia and neoplasia in progressively infected cats. The outcome of FeLV infection is influenced by the host immune response; progressively infected cats demonstrate weaker immune responses compared to regressively infected cats. In this study, humoral immune responses were examined in 180 samples collected from 123 domestic cats that had been naturally exposed to FeLV, using a novel ELISA to measure antibodies recognizing the FeLV surface unit (SU) glycoprotein in plasma samples. A correlation was demonstrated between the strength of the humoral immune response to the SU protein and the outcome of exposure. Cats with regressive infection demonstrated higher antibody responses to the SU protein compared to cats belonging to other outcome groups, and samples from cats with regressive infection contained virus neutralising antibodies. These results demonstrate that an ELISA that assesses the humoral response to FeLV SU complements the use of viral diagnostic tests to define the outcome of exposure to FeLV. Together these tests could allow the rapid identification of regressively infected cats that are unlikely to develop FeLV-related disease.
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Affiliation(s)
- Yasmin A. Parr
- MRC—University of Glasgow Centre for Virus Research, Glasgow, Scotland G61 1QH, UK; (B.J.W.); (M.J.H.)
- Correspondence: ; Tel.: +44-0-141-330-3444
| | | | - Julie K. Levy
- Maddie’s Shelter Medicine Program, University of Florida, Gainesville, FL 32608, USA;
| | - Michael McDonald
- Veterinary Diagnostic Services, University of Glasgow, Glasgow, Scotland G61 1QH, UK;
| | | | - Brian J. Willett
- MRC—University of Glasgow Centre for Virus Research, Glasgow, Scotland G61 1QH, UK; (B.J.W.); (M.J.H.)
| | - Margaret J. Hosie
- MRC—University of Glasgow Centre for Virus Research, Glasgow, Scotland G61 1QH, UK; (B.J.W.); (M.J.H.)
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5
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Sinha A, Singh AK, Kadni TS, Mullick J, Sahu A. Virus-Encoded Complement Regulators: Current Status. Viruses 2021; 13:v13020208. [PMID: 33573085 PMCID: PMC7912105 DOI: 10.3390/v13020208] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2020] [Revised: 01/21/2021] [Accepted: 01/22/2021] [Indexed: 11/29/2022] Open
Abstract
Viruses require a host for replication and survival and hence are subjected to host immunological pressures. The complement system, a crucial first response of the host immune system, is effective in targeting viruses and virus-infected cells, and boosting the antiviral innate and acquired immune responses. Thus, the system imposes a strong selection pressure on viruses. Consequently, viruses have evolved multiple countermeasures against host complement. A major mechanism employed by viruses to subvert the complement system is encoding proteins that target complement. Since viruses have limited genome size, most of these proteins are multifunctional in nature. In this review, we provide up to date information on the structure and complement regulatory functions of various viral proteins.
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Affiliation(s)
- Anwesha Sinha
- Complement Biology Laboratory, National Centre for Cell Science, S. P. Pune University Campus, Ganeskhind, Pune 411007, India; (A.S.); (A.K.S.); (T.S.K.)
| | - Anup Kumar Singh
- Complement Biology Laboratory, National Centre for Cell Science, S. P. Pune University Campus, Ganeskhind, Pune 411007, India; (A.S.); (A.K.S.); (T.S.K.)
| | - Trupti Satish Kadni
- Complement Biology Laboratory, National Centre for Cell Science, S. P. Pune University Campus, Ganeskhind, Pune 411007, India; (A.S.); (A.K.S.); (T.S.K.)
| | - Jayati Mullick
- Polio Virology Group, Microbial Containment Complex, ICMR-National Institute of Virology, Pune 411021, India;
| | - Arvind Sahu
- Complement Biology Laboratory, National Centre for Cell Science, S. P. Pune University Campus, Ganeskhind, Pune 411007, India; (A.S.); (A.K.S.); (T.S.K.)
- Correspondence: ; Tel.: +91-20-2570-8083; Fax: +91-20-2569-2259
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6
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Kaposi's Sarcoma-Associated Herpesvirus and Host Interaction by the Complement System. Pathogens 2020; 9:pathogens9040260. [PMID: 32260199 PMCID: PMC7237997 DOI: 10.3390/pathogens9040260] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Revised: 03/19/2020] [Accepted: 04/02/2020] [Indexed: 12/31/2022] Open
Abstract
Kaposi’s sarcoma-associated herpesvirus (KSHV) modulates the immune response to allow the virus to establish persistent infection in the host and facilitate the development of KSHV-associated cancer. The complement system has a central role in the defense against pathogens. Hence, KSHV has adopted an evasion strategy for complement attack using the viral protein encoded by KSHV open reading frame 4. However, despite this defense mechanism, the complement system appears to become activated in KSHV-infected cells as well as in the region surrounding Kaposi’s sarcoma tumors. Given that the complement system can affect cell fate as well as the inflammatory microenvironment, complement activation is likely associated with KSHV pathogenesis. A better understanding of the interplay between KSHV and the complement system may, therefore, translate into the development of novel therapeutic interventions for KSHV-associated tumors. In this review, the mechanisms and functions of complement activation in KSHV-infected cells are discussed.
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7
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Maloney BE, Perera KD, Saunders DRD, Shadipeni N, Fleming SD. Interactions of viruses and the humoral innate immune response. Clin Immunol 2020; 212:108351. [PMID: 32028020 DOI: 10.1016/j.clim.2020.108351] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Revised: 02/01/2020] [Accepted: 02/01/2020] [Indexed: 12/13/2022]
Abstract
The innate immune response is crucial for defense against virus infections where the complement system, coagulation cascade and natural antibodies play key roles. These immune components are interconnected in an intricate network and are tightly regulated to maintain homeostasis and avoid uncontrolled immune responses. Many viruses in turn have evolved to modulate these interactions through various strategies to evade innate immune activation. This review summarizes the current understanding on viral strategies to inhibit the activation of complement and coagulation cascades, evade natural antibody-mediated clearance and utilize complement regulatory mechanisms to their advantage.
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Affiliation(s)
- Bailey E Maloney
- Department of Diagnostic Medicine and Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS, USA
| | - Krishani Dinali Perera
- Department of Diagnostic Medicine and Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS, USA
| | - Danielle R D Saunders
- Department of Diagnostic Medicine and Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS, USA
| | - Naemi Shadipeni
- Department of Diagnostic Medicine and Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS, USA
| | - Sherry D Fleming
- Division of Biology, Kansas State University, Manhattan, KS, USA.
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8
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TerBush AA, Hafkamp F, Lee HJ, Coscoy L. A Kaposi's Sarcoma-Associated Herpesvirus Infection Mechanism Is Independent of Integrins α3β1, αVβ3, and αVβ5. J Virol 2018; 92:e00803-18. [PMID: 29899108 PMCID: PMC6096800 DOI: 10.1128/jvi.00803-18] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Accepted: 06/08/2018] [Indexed: 12/24/2022] Open
Abstract
Host receptor usage by Kaposi's sarcoma-associated herpesvirus (KSHV) has been best studied using primary microvascular endothelial and fibroblast cells, although the virus infects a wide variety of cell types in culture and in natural infections. In these two infection models, KSHV adheres to the cell though heparan sulfate (HS) binding and then interacts with a complex of EphA2, xCT, and integrins α3β1, αVβ3, and αVβ5 to catalyze viral entry. We dissected this receptor complex at the genetic level with CRISPR-Cas9 to precisely determine receptor usage in two epithelial cell lines. Surprisingly, we discovered an infection mechanism that requires HS and EphA2 but is independent of αV- and β1-family integrin expression. Furthermore, infection appears to be independent of the EphA2 intracellular domain. We also demonstrated that while two other endogenous Eph receptors were dispensable for KSHV infection, transduced EphA4 and EphA5 significantly enhanced infection of cells lacking EphA2.IMPORTANCE Our data reveal an integrin-independent route of KSHV infection and suggest that multiple Eph receptors besides EphA2 can promote and regulate infection. Since integrins and Eph receptors are large protein families with diverse expression patterns across cells and tissues, we propose that KSHV may engage with several proteins from both families in different combinations to negotiate successful entry into diverse cell types.
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Affiliation(s)
- Allison Alwan TerBush
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California, USA
| | - Florianne Hafkamp
- Graduate School of Life Sciences, Utrecht University, Utrecht, Netherlands
| | - Hee Jun Lee
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California, USA
| | - Laurent Coscoy
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California, USA
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9
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Agrawal P, Nawadkar R, Ojha H, Kumar J, Sahu A. Complement Evasion Strategies of Viruses: An Overview. Front Microbiol 2017; 8:1117. [PMID: 28670306 PMCID: PMC5472698 DOI: 10.3389/fmicb.2017.01117] [Citation(s) in RCA: 106] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Accepted: 05/31/2017] [Indexed: 12/11/2022] Open
Abstract
Being a major first line of immune defense, the complement system keeps a constant vigil against viruses. Its ability to recognize large panoply of viruses and virus-infected cells, and trigger the effector pathways, results in neutralization of viruses and killing of the infected cells. This selection pressure exerted by complement on viruses has made them evolve a multitude of countermeasures. These include targeting the recognition molecules for the avoidance of detection, targeting key enzymes and complexes of the complement pathways like C3 convertases and C5b-9 formation - either by encoding complement regulators or by recruiting membrane-bound and soluble host complement regulators, cleaving complement proteins by encoding protease, and inhibiting the synthesis of complement proteins. Additionally, viruses also exploit the complement system for their own benefit. For example, they use complement receptors as well as membrane regulators for cellular entry as well as their spread. Here, we provide an overview on the complement subversion mechanisms adopted by the members of various viral families including Poxviridae, Herpesviridae, Adenoviridae, Flaviviridae, Retroviridae, Picornaviridae, Astroviridae, Togaviridae, Orthomyxoviridae and Paramyxoviridae.
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Affiliation(s)
- Palak Agrawal
- Complement Biology Laboratory, National Centre for Cell Science, Savitribai Phule Pune UniversityPune, India
| | - Renuka Nawadkar
- Complement Biology Laboratory, National Centre for Cell Science, Savitribai Phule Pune UniversityPune, India
| | - Hina Ojha
- Complement Biology Laboratory, National Centre for Cell Science, Savitribai Phule Pune UniversityPune, India
| | - Jitendra Kumar
- Complement Biology Laboratory, National Centre for Cell Science, Savitribai Phule Pune UniversityPune, India
| | - Arvind Sahu
- Complement Biology Laboratory, National Centre for Cell Science, Savitribai Phule Pune UniversityPune, India
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10
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Abstract
Kaposi’s sarcoma-associated herpesvirus (KSHV) primarily persists as a latent episome in infected cells. During latent infection, only a limited number of viral genes are expressed that help to maintain the viral episome and prevent lytic reactivation. The latent KSHV genome persists as a highly ordered chromatin structure with bivalent chromatin marks at the promoter-regulatory region of the major immediate-early gene promoter. Various stimuli can induce chromatin modifications to an active euchromatic epigenetic mark, leading to the expression of genes required for the transition from the latent to the lytic phase of KSHV life cycle. Enhanced replication and transcription activator (RTA) gene expression triggers a cascade of events, resulting in the modulation of various cellular pathways to support viral DNA synthesis. RTA also binds to the origin of lytic DNA replication to recruit viral, as well as cellular, proteins for the initiation of the lytic DNA replication of KSHV. In this review we will discuss some of the pivotal genetic and epigenetic factors that control KSHV reactivation from the transcriptionally restricted latent program.
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11
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Viral semaphorin inhibits dendritic cell phagocytosis and migration but is not essential for gammaherpesvirus-induced lymphoproliferation in malignant catarrhal fever. J Virol 2015; 89:3630-47. [PMID: 25589653 DOI: 10.1128/jvi.03634-14] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
UNLABELLED Viral semaphorins are semaphorin 7A (sema7A) mimics found in pox- and herpesviruses. Among herpesviruses, semaphorins are encoded by gammaherpesviruses of the Macavirus genus only. Alcelaphine herpesvirus 1 (AlHV-1) is a macavirus that persistently infects wildebeest asymptomatically but induces malignant catarrhal fever (MCF) when transmitted to several species of susceptible ruminants and the rabbit model. MCF is caused by the activation/proliferation of latently infected T lymphocytes. Viral semaphorins have been suggested to mediate immune evasion mechanisms and/or directly alter host T cell function. We studied AlHV-sema, the viral semaphorin encoded by the A3 gene of AlHV-1. Phylogenetic analyses revealed independent acquisition of pox- and herpesvirus semaphorins, suggesting that these proteins might have distinct functions. AlHV-sema showed a predicted three-dimensional structure very similar to sema7A and conserved key residues in sema7A-plexinC1 interaction. Expression analyses revealed that AlHV-sema is a secreted 93-kDa glycoprotein expressed during the early phase of virus replication. Purified AlHV-sema was able to bind to fibroblasts and dendritic cells and induce F-actin condensation and cell retraction through a plexinC1 and Rho/cofilin-dependent mechanism. Cytoskeleton rearrangement was further associated with inhibition of phagocytosis by dendritic cells and migration to the draining lymph node. Next, we generated recombinant viruses and demonstrated that the lack of A3 did not significantly affect virus growth in vitro and did not impair MCF induction and associated lymphoproliferative lesions. In conclusion, AlHV-sema has immune evasion functions through mechanisms similar to poxvirus semaphorin but is not directly involved in host T cell activation during MCF. IMPORTANCE Whereas most poxviruses encode viral semaphorins, semaphorin-like genes have only been identified in few gammaherpesviruses belonging to the Macavirus genus. Alcelaphine herpesvirus 1 (AlHV-1) is a macavirus carried asymptomatically by wildebeest but induces a latency-associated lymphoproliferative disease of T lymphocytes in various ruminant species, namely, malignant catarrhal fever (MCF). Viral semaphorins have been hypothesized to have immune evasion functions and/or be involved in activating latently infected T cells. We present evidence that the viral semaphorin AlHV-sema inhibits dendritic cell phagocytosis and migration to the draining lymph node, both being indispensable mechanisms for protective antiviral responses. Next, we engineered recombinant viruses unable to express AlHV-sema and demonstrated that this protein is dispensable for the induction of MCF. In conclusion, this study suggests that herpesvirus and poxvirus semaphorins have independently evolved similar functions to thwart the immune system of the host while AlHV-sema is not directly involved in MCF-associated T-cell activation.
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12
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Ojha H, Panwar HS, Gorham RD, Morikis D, Sahu A. Viral regulators of complement activation: structure, function and evolution. Mol Immunol 2014; 61:89-99. [PMID: 24976595 DOI: 10.1016/j.molimm.2014.06.004] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2014] [Revised: 05/30/2014] [Accepted: 06/01/2014] [Indexed: 11/25/2022]
Abstract
The complement system surveillance in the host is effective in controlling viral propagation. Consequently, to subvert this effector mechanism, viruses have developed a series of adaptations. One among these is encoding mimics of host regulators of complement activation (RCA) which help viruses to avoid being labeled as 'foreign' and protect them from complement-mediated neutralization and complement-enhanced antiviral adaptive immunity. In this review, we provide an overview on the structure, function and evolution of viral RCA proteins.
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Affiliation(s)
- Hina Ojha
- National Centre for Cell Science, Pune University Campus, Ganeshkhind, Pune 411007, India
| | - Hemendra Singh Panwar
- National Centre for Cell Science, Pune University Campus, Ganeshkhind, Pune 411007, India
| | - Ronald D Gorham
- Department of Bioengineering, University of California, Riverside, CA 92521, USA
| | - Dimitrios Morikis
- Department of Bioengineering, University of California, Riverside, CA 92521, USA.
| | - Arvind Sahu
- National Centre for Cell Science, Pune University Campus, Ganeshkhind, Pune 411007, India.
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13
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Interplay between Kaposi's sarcoma-associated herpesvirus and the innate immune system. Cytokine Growth Factor Rev 2014; 25:597-609. [PMID: 25037686 DOI: 10.1016/j.cytogfr.2014.06.001] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2014] [Accepted: 06/16/2014] [Indexed: 02/04/2023]
Abstract
Understanding of the innate immune response to viral infections is rapidly progressing, especially with regards to the detection of DNA viruses. Kaposi's sarcoma-associated herpesvirus (KSHV) is a large dsDNA virus that is responsible for three human diseases: Kaposi's sarcoma, primary effusion lymphoma and multicentric Castleman's disease. The major target cells of KSHV (B cells and endothelial cells) express a wide range of pattern recognition receptors (PRRs) and play a central role in mobilizing inflammatory responses. On the other hand, KSHV encodes an array of immune evasion genes, including several pirated host genes, which interfere with multiple aspects of the immune response. This review summarizes current understanding of innate immune recognition of KSHV and the role of immune evasion genes that shape the antiviral and inflammatory responses.
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Holmquist E, Okroj M, Nodin B, Jirström K, Blom AM. Sushi domain‐containing protein 4 (SUSD4) inhibits complement by disrupting the formation of the classical C3 convertase. FASEB J 2013; 27:2355-66. [DOI: 10.1096/fj.12-222042] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Emelie Holmquist
- Department of Laboratory MedicineDivision of Medical Protein ChemistryLund UniversityMalmöSweden
| | - Marcin Okroj
- Department of Laboratory MedicineDivision of Medical Protein ChemistryLund UniversityMalmöSweden
| | - Björn Nodin
- Department of Clinical SciencesDivision of PathologyLund UniversityLundSweden
| | - Karin Jirström
- Department of Clinical SciencesDivision of PathologyLund UniversityLundSweden
| | - Anna M. Blom
- Department of Laboratory MedicineDivision of Medical Protein ChemistryLund UniversityMalmöSweden
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15
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Stewart H, Adema KW, McMonagle EL, Hosie MJ, Willett BJ. Identification of novel subgroup A variants with enhanced receptor binding and replicative capacity in primary isolates of anaemogenic strains of feline leukaemia virus. Retrovirology 2012; 9:48. [PMID: 22650160 PMCID: PMC3403869 DOI: 10.1186/1742-4690-9-48] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2012] [Accepted: 05/31/2012] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND The development of anaemia in feline leukaemia virus (FeLV)-infected cats is associated with the emergence of a novel viral subgroup, FeLV-C. FeLV-C arises from the subgroup that is transmitted, FeLV-A, through alterations in the amino acid sequence of the receptor binding domain (RBD) of the envelope glycoprotein that result in a shift in the receptor usage and the cell tropism of the virus. The factors that influence the transition from subgroup A to subgroup C remain unclear, one possibility is that a selective pressure in the host drives the acquisition of mutations in the RBD, creating A/C intermediates with enhanced abilities to interact with the FeLV-C receptor, FLVCR. In order to understand further the emergence of FeLV-C in the infected cat, we examined primary isolates of FeLV-C for evidence of FeLV-A variants that bore mutations consistent with a gradual evolution from FeLV-A to FeLV-C. RESULTS Within each isolate of FeLV-C, we identified variants that were ostensibly subgroup A by nucleic acid sequence comparisons, but which bore mutations in the RBD. One such mutation, N91D, was present in multiple isolates and when engineered into a molecular clone of the prototypic FeLV-A (Glasgow-1), enhanced replication was noted in feline cells. Expression of the N91D Env on murine leukaemia virus (MLV) pseudotypes enhanced viral entry mediated by the FeLV-A receptor THTR1 while soluble FeLV-A Env bearing the N91D mutation bound more efficiently to mouse or guinea pig cells bearing the FeLV-A and -C receptors. Long-term in vitro culture of variants bearing the N91D substitution in the presence of anti-FeLV gp70 antibodies did not result in the emergence of FeLV-C variants, suggesting that additional selective pressures in the infected cat may drive the subsequent evolution from subgroup A to subgroup C. CONCLUSIONS Our data support a model in which variants of FeLV-A, bearing subtle differences in the RBD of Env, may be predisposed towards enhanced replication in vivo and subsequent conversion to FeLV-C. The selection pressures in vivo that drive the emergence of FeLV-C in a proportion of infected cats remain to be established.
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MESH Headings
- Amino Acid Sequence
- Animals
- Antibodies, Neutralizing/immunology
- Antibodies, Viral/immunology
- Cats
- Cell Line
- Cloning, Molecular
- Fibroblasts/virology
- Glycoproteins/genetics
- Guinea Pigs
- HEK293 Cells
- Humans
- Leukemia Virus, Feline/classification
- Leukemia Virus, Feline/pathogenicity
- Leukemia Virus, Feline/physiology
- Leukemia Virus, Murine/genetics
- Membrane Transport Proteins/genetics
- Membrane Transport Proteins/metabolism
- Mice
- Molecular Sequence Data
- Mutagenesis, Site-Directed
- Neutralization Tests
- Protein Binding
- RNA, Viral/genetics
- Receptors, Virus/metabolism
- Selection, Genetic
- Viral Envelope Proteins/genetics
- Virus Attachment
- Virus Internalization
- Virus Replication
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Affiliation(s)
- Hazel Stewart
- Medical Research Council-University of Glasgow Centre for Virus Research, Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, 464 Bearsden Road, Glasgow, UK
| | - Karen W Adema
- Medical Research Council-University of Glasgow Centre for Virus Research, Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, 464 Bearsden Road, Glasgow, UK
| | - Elizabeth L McMonagle
- Medical Research Council-University of Glasgow Centre for Virus Research, Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, 464 Bearsden Road, Glasgow, UK
| | - Margaret J Hosie
- Medical Research Council-University of Glasgow Centre for Virus Research, Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, 464 Bearsden Road, Glasgow, UK
| | - Brian J Willett
- Medical Research Council-University of Glasgow Centre for Virus Research, Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, 464 Bearsden Road, Glasgow, UK
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16
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Lee HR, Brulois K, Wong L, Jung JU. Modulation of Immune System by Kaposi's Sarcoma-Associated Herpesvirus: Lessons from Viral Evasion Strategies. Front Microbiol 2012; 3:44. [PMID: 22403573 PMCID: PMC3293256 DOI: 10.3389/fmicb.2012.00044] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2011] [Accepted: 01/27/2012] [Indexed: 12/14/2022] Open
Abstract
Kaposi's sarcoma-associated herpesvirus (KSHV), a member of the herpesvirus family, has evolved to establish a long-term, latent infection of cells such that while they carry the viral genome gene expression is highly restricted. Latency is a state of cryptic viral infection associated with genomic persistence in their host and this hallmark of KSHV infection leads to several clinical-epidemiological diseases such as KS, a plasmablastic variant of multicentric Castleman's disease, and primary effusion lymphoma upon immune suppression of infected hosts. In order to sustain efficient life-long persistency as well as their life cycle, KSHV dedicates a large portion of its genome to encode immunomodulatory proteins that antagonize its host's immune system. In this review, we will describe our current knowledge of the immune evasion strategies employed by KSHV at distinct stages of its viral life cycle to control the host's immune system.
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Affiliation(s)
- Hye-Ra Lee
- Department of Molecular Microbiology and Immunology, Keck School of Medicine, University of Southern California Los Angeles, CA, USA
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17
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Infections of people with complement deficiencies and patients who have undergone splenectomy. Clin Microbiol Rev 2010; 23:740-80. [PMID: 20930072 DOI: 10.1128/cmr.00048-09] [Citation(s) in RCA: 252] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The complement system comprises several fluid-phase and membrane-associated proteins. Under physiological conditions, activation of the fluid-phase components of complement is maintained under tight control and complement activation occurs primarily on surfaces recognized as "nonself" in an attempt to minimize damage to bystander host cells. Membrane complement components act to limit complement activation on host cells or to facilitate uptake of antigens or microbes "tagged" with complement fragments. While this review focuses on the role of complement in infectious diseases, work over the past couple of decades has defined several important functions of complement distinct from that of combating infections. Activation of complement in the fluid phase can occur through the classical, lectin, or alternative pathway. Deficiencies of components of the classical pathway lead to the development of autoimmune disorders and predispose individuals to recurrent respiratory infections and infections caused by encapsulated organisms, including Streptococcus pneumoniae, Neisseria meningitidis, and Haemophilus influenzae. While no individual with complete mannan-binding lectin (MBL) deficiency has been identified, low MBL levels have been linked to predisposition to, or severity of, several diseases. It appears that MBL may play an important role in children, who have a relatively immature adaptive immune response. C3 is the point at which all complement pathways converge, and complete deficiency of C3 invariably leads to severe infections, including those caused by meningococci and pneumococci. Deficiencies of the alternative and terminal complement pathways result in an almost exclusive predisposition to invasive meningococcal disease. The spleen plays an important role in antigen processing and the production of antibodies. Splenic macrophages are critical in clearing opsonized encapsulated bacteria (such as pneumococci, meningococci, and Escherichia coli) and intraerythrocytic parasites such as those causing malaria and babesiosis, which explains the fulminant nature of these infections in persons with anatomic or functional asplenia. Paramount to the management of patients with complement deficiencies and asplenia is educating patients about their predisposition to infection and the importance of preventive immunizations and seeking prompt medical attention.
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18
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Okroj M, Tedeschi R, Mancuso R, Brambilla L, Tourlaki A, Dillner J, Blom AM. Prevalence of antibodies against Kaposi's sarcoma associated herpes virus (KSHV) complement inhibitory protein (KCP) in KSHV-related diseases and their correlation with clinical parameters. Vaccine 2010; 29:1129-34. [PMID: 21134448 DOI: 10.1016/j.vaccine.2010.11.070] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2010] [Revised: 11/15/2010] [Accepted: 11/22/2010] [Indexed: 11/30/2022]
Abstract
Kaposi's sarcoma-associated herpes virus (KSHV) encodes its own inhibitor of the complement system, designated KSHV complement control protein (KCP). Previously, we detected anti-KCP antibodies in a small group of 22 patients suffering from Kaposi's sarcoma (KS) and KSHV-related lymphoproliferative diseases (Vaccine, 25:8102-9). Anti-KCP antibodies were more prevalent in individuals suffering from KSHV-related lymphomas than KS and also in those with high titer of antibodies against lytic KSHV antigens. Herein we analyze anti-KCP antibodies in 175 individuals originating from three different groups from northern Sweden or Italy, which included patients suffering from classical or HIV-associated KS, Multicentric Castleman's Disease, KSHV-associated solid lymphoma, pleural effusion lymphoma and healthy individuals with detectable KSHV immune response. Our current study confirmed previous observations concerning antibody prevalence but we also analyzed correlations between anti-KCP antibodies and classical KS evolution, clinical stage and viral load in body fluids. Furthermore, we show that patient's anti-KCP antibodies are able to decrease the ability of KCP to inhibit complement. This fact combined with results of statistical analysis suggests that KCP inactivation by specific antibodies may influence progression of classical KS.
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Affiliation(s)
- Marcin Okroj
- Department of Laboratory Medicine Malmö, Lund University, 20502 Malmö, Sweden
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19
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Pyaram K, Yadav VN, Reza MJ, Sahu A. Virus–complement interactions: an assiduous struggle for dominance. Future Virol 2010. [DOI: 10.2217/fvl.10.60] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The complement system is a major component of the innate immune system that recognizes invading pathogens and eliminates them by means of an array of effector mechanisms, in addition to using direct lytic destruction. Viruses, in spite of their small size and simple composition, are also deftly recognized and neutralized by the complement system. In turn, as a result of years of coevolution with the host, viruses have developed multiple mechanisms to evade the host complement. These complex interactions between the complement system and viruses have been an area of focus for over three decades. In this article, we provide a broad overview of the field using key examples and up-to-date information on the complement-evasion strategies of viruses.
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Affiliation(s)
- Kalyani Pyaram
- National Centre for Cell Science, Pune University Campus, Ganeshkhind, Pune 411007, India
| | - Viveka Nand Yadav
- National Centre for Cell Science, Pune University Campus, Ganeshkhind, Pune 411007, India
| | - Malik Johid Reza
- National Centre for Cell Science, Pune University Campus, Ganeshkhind, Pune 411007, India
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20
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Ahmad M, Raut S, Pyaram K, Kamble A, Mullick J, Sahu A. Domain Swapping Reveals Complement Control Protein Modules Critical for Imparting Cofactor and Decay-Accelerating Activities in Vaccinia Virus Complement Control Protein. THE JOURNAL OF IMMUNOLOGY 2010; 185:6128-37. [DOI: 10.4049/jimmunol.1001617] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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21
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Steer B, Adler B, Jonjic S, Stewart JP, Adler H. A gammaherpesvirus complement regulatory protein promotes initiation of infection by activation of protein kinase Akt/PKB. PLoS One 2010; 5:e11672. [PMID: 20657771 PMCID: PMC2908122 DOI: 10.1371/journal.pone.0011672] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2010] [Accepted: 06/27/2010] [Indexed: 12/22/2022] Open
Abstract
Background Viruses have evolved to evade the host's complement system. The open reading frames 4 (ORF4) of gammaherpesviruses encode homologs of regulators of complement activation (RCA) proteins, which inhibit complement activation at the level of C3 and C4 deposition. Besides complement regulation, these proteins are involved in heparan sulfate and glycosaminoglycan binding, and in case of MHV-68, also in viral DNA synthesis in macrophages. Methodology/Principal Findings Here, we made use of MHV-68 to study the role of ORF4 during infection of fibroblasts. While attachment and penetration of virions lacking the RCA protein were not affected, we observed a delayed delivery of the viral genome to the nucleus of infected cells. Analysis of the phosphorylation status of a variety of kinases revealed a significant reduction in phosphorylation of the protein kinase Akt in cells infected with ORF4 mutant virus, when compared to cells infected with wt virus. Consistent with a role of Akt activation in initial stages of infection, inhibition of Akt signaling in wt virus infected cells resulted in a phenotype resembling the phenotype of the ORF4 mutant virus, and activation of Akt by addition of insulin partially reversed the phenotype of the ORF4 mutant virus. Importantly, the homologous ORF4 of KSHV was able to rescue the phenotype of the MHV-68 ORF4 mutant, indicating that ORF4 is functionally conserved and that ORF4 of KSHV might have a similar function in infection initiation. Conclusions/Significance In summary, our studies demonstrate that ORF4 contributes to efficient infection by activation of the protein kinase Akt and thus reveal a novel function of a gammaherpesvirus RCA protein.
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Affiliation(s)
- Beatrix Steer
- The Institute of Molecular Immunology, Clinical Cooperation Group Hematopoietic Cell Transplantation, Helmholtz Zentrum München - German Research Center for Environmental Health, Munich, Germany
| | - Barbara Adler
- Max von Pettenkofer-Institute, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Stipan Jonjic
- Department of Histology and Embryology, Faculty of Medicine, University of Rijeka, Rijeka, Croatia
| | - James P. Stewart
- Centre for Comparative Infectious Diseases, Department of Medical Microbiology, University of Liverpool, Liverpool, United Kingdom
| | - Heiko Adler
- The Institute of Molecular Immunology, Clinical Cooperation Group Hematopoietic Cell Transplantation, Helmholtz Zentrum München - German Research Center for Environmental Health, Munich, Germany
- * E-mail:
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22
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Pyaram K, Kieslich CA, Yadav VN, Morikis D, Sahu A. Influence of electrostatics on the complement regulatory functions of Kaposica, the complement inhibitor of Kaposi's sarcoma-associated herpesvirus. THE JOURNAL OF IMMUNOLOGY 2010; 184:1956-67. [PMID: 20089702 DOI: 10.4049/jimmunol.0903261] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Kaposica, the complement regulator of Kaposi's sarcoma-associated herpesvirus, inhibits complement by supporting factor I-mediated inactivation of the proteolytically activated form of C3 (C3b) and C4 (C4b) (cofactor activity [CFA]) and by accelerating the decay of classical and alternative pathway C3-convertases (decay-accelerating activity [DAA]). Previous data suggested that electrostatic interactions play a critical role in the binding of viral complement regulators to their targets, C3b and C4b. We therefore investigated how electrostatic potential on Kaposica influences its activities. We built a homology structure of Kaposica and calculated the electrostatic potential of the molecule, using the Poisson-Boltzmann equation. Mutants were then designed to alter the overall positive potential of the molecule or of each of its domains and linkers by mutating Lys/Arg to Glu/Gln, and the functional activities of the expressed mutants were analyzed. Our data indicate that 1) positive potential at specific sites and not the overall positive potential on the molecule guides the CFAs and classical pathway DAA; 2) positive potential around the linkers between complement control protein domains (CCPs) 1-2 and 2-3 is more important for DAAs than for CFAs; 3) positive potential in CCP1 is crucial for binding to C3b and C4b, and thereby its functional activities; 4) conversion to negative or enhancement of negative potential for CCPs 2-4 has a marked effect on C3b-linked activities as opposed to C4b-linked activities; and 5) reversal of the electrostatic potential of CCP4 to negative has a differential effect on classical and alternative pathway DAAs. Together, our data provide functional relevance to conservation of positive potential in CCPs 1 and 4 and the linkers of viral complement regulators.
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Affiliation(s)
- Kalyani Pyaram
- National Centre for Cell Science, Pune University Campus, Ganeshkhind, Pune, India
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23
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Cai Q, Verma SC, Lu J, Robertson ES. Molecular biology of Kaposi's sarcoma-associated herpesvirus and related oncogenesis. Adv Virus Res 2010; 78:87-142. [PMID: 21040832 PMCID: PMC3142360 DOI: 10.1016/b978-0-12-385032-4.00003-3] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Kaposi's Sarcoma-associated Herpesvirus (KSHV), also known as human herpesvirus 8 (HHV-8), is the most recently identified human tumor virus,and is associated with the pathogenesis of Kaposi's sarcoma and two lymphoproliferative disorders known to occur frequently in AIDS patients-primary effusion lymphoma and multicentric Castleman disease. In the 15 years since its discovery, intense studies have demonstrated an etiologic role for KSHV in the development of these malignancies. Here, we review the recent advances linked to understanding KSHV latent and lytic life cycle and the molecular mechanisms of KSHV-mediated oncogenesis in terms of transformation, cell signaling, cell growth and survival, angiogenesis, immune invasion and response to microenvironmental stress, and highlight the potential therapeutic targets for blocking KSHV tumorigenesis.
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Affiliation(s)
- Qiliang Cai
- Department of Microbiology, Abramson, Comprehensive Cancer Center, University of Pennsylvania Medical School, Philadelphia, Pennsylvania, USA
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24
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Mapping of functional domains in herpesvirus saimiri complement control protein homolog: complement control protein domain 2 is the smallest structural unit displaying cofactor and decay-accelerating activities. J Virol 2009; 83:10299-304. [PMID: 19640995 DOI: 10.1128/jvi.00217-09] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Herpesvirus saimiri encodes a functional homolog of human regulator-of-complement-activation proteins named CCPH that inactivates complement by accelerating the decay of C3 convertases and by serving as a cofactor in factor I-mediated inactivation of their subunits C3b and C4b. Here, we map the functional domains of CCPH. We demonstrate that short consensus repeat 2 (SCR2) is the minimum domain essential for classical/lectin pathway C3 convertase decay-accelerating activity as well as for factor I cofactor activity for C3b and C4b. Thus, CCPH is the first example wherein a single SCR domain has been shown to display complement regulatory functions.
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25
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Aresté C, Blackbourn DJ. Modulation of the immune system by Kaposi's sarcoma-associated herpesvirus. Trends Microbiol 2009; 17:119-29. [PMID: 19230674 DOI: 10.1016/j.tim.2008.12.001] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2008] [Revised: 12/10/2008] [Accepted: 12/11/2008] [Indexed: 12/24/2022]
Abstract
The most recently identified human herpesvirus is Kaposi's sarcoma-associated herpesvirus (KSHV). It causes Kaposi's sarcoma, a tumour occurring most commonly in untreated AIDS patients and the leading cancer of men in certain parts of Africa. KSHV might also contribute to the pathogenesis of primary effusion lymphoma and multicentric Castleman's disease. The genome of KSHV contains 86 genes, almost a quarter of which encode proteins with either demonstrated or potential immunoregulatory activity. They include homologues of cellular proteins and unique KSHV proteins that can deregulate many aspects of the immune response, including T- and B-cell functions, complement activation, the innate antiviral interferon response and natural killer cell activity. The functions of these proteins and the ways in which they perturb the normal immune response are the subjects of the present review.
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Affiliation(s)
- Cristina Aresté
- Cancer Research UK Institute for Cancer Studies, University of Birmingham, Birmingham B15 2TT, UK
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26
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Okroj M, Mark L, Stokowska A, Wong SW, Rose N, Blackbourn DJ, Villoutreix BO, Spiller OB, Blom AM. Characterization of the complement inhibitory function of rhesus rhadinovirus complement control protein (RCP). J Biol Chem 2008; 284:505-514. [PMID: 18990693 DOI: 10.1074/jbc.m806669200] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Rhesus rhadinovirus (RRV) is currently the closest known, fully sequenced homolog of human Kaposi sarcoma-associated herpesvirus. Both these viruses encode complement inhibitors as follows: Kaposi sarcoma-associated herpesvirus-complement control protein (KCP) and RRV-complement control protein (RCP). Previously we characterized in detail the functional properties of KCP as a complement inhibitor. Here, we performed comparative analyses for two variants of RCP protein, encoded by RRV strains H26-95 and 17577. Both RCP variants and KCP inhibited human and rhesus complement when tested in hemolytic assays measuring all steps of activation via the classical and the alternative pathway. RCP variants from both RRV strains supported C3b and C4b degradation by factor I and decay acceleration of the classical C3 convertase, similar to KCP. Additionally, the 17577 RCP variant accelerated decay of the alternative C3 convertase, which was not seen for KCP. In contrast to KCP, RCP showed no affinity to heparin and is the first described complement inhibitor in which the binding site for C3b/C4b does not interact with heparin. Molecular modeling shows a structural disruption in the region of RCP that corresponds to the KCP-heparin-binding site. This makes RRV a superior model for future in vivo investigations of complement evasion, as RCP does not play a supportive role in viral attachment as KCP does.
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Affiliation(s)
- Marcin Okroj
- Department of Laboratory Medicine, Lund University, University Hospital Malmo¨, Malmo¨ S-20502, Sweden, the Vaccine and Gene Therapy Institute, Oregon Health and Science University, Beaverton, Oregon 97006, the National Institute for Biological Standards and Control, Herts EN6 3QG, United Kingdom, the Cancer Research UK Institute for Cancer Studies, University of Birmingham, Birmingham B15 2TT, United Kingdom, INSERM MTi, University Paris Diderot, Paris 75013, France, and the Department of Child Health, Cardiff University, Wales School of Medicine, Cardiff CF14 4XN, United Kingdom
| | - Linda Mark
- Department of Laboratory Medicine, Lund University, University Hospital Malmo¨, Malmo¨ S-20502, Sweden, the Vaccine and Gene Therapy Institute, Oregon Health and Science University, Beaverton, Oregon 97006, the National Institute for Biological Standards and Control, Herts EN6 3QG, United Kingdom, the Cancer Research UK Institute for Cancer Studies, University of Birmingham, Birmingham B15 2TT, United Kingdom, INSERM MTi, University Paris Diderot, Paris 75013, France, and the Department of Child Health, Cardiff University, Wales School of Medicine, Cardiff CF14 4XN, United Kingdom
| | - Anna Stokowska
- Department of Laboratory Medicine, Lund University, University Hospital Malmo¨, Malmo¨ S-20502, Sweden, the Vaccine and Gene Therapy Institute, Oregon Health and Science University, Beaverton, Oregon 97006, the National Institute for Biological Standards and Control, Herts EN6 3QG, United Kingdom, the Cancer Research UK Institute for Cancer Studies, University of Birmingham, Birmingham B15 2TT, United Kingdom, INSERM MTi, University Paris Diderot, Paris 75013, France, and the Department of Child Health, Cardiff University, Wales School of Medicine, Cardiff CF14 4XN, United Kingdom
| | - Scott W Wong
- Department of Laboratory Medicine, Lund University, University Hospital Malmo¨, Malmo¨ S-20502, Sweden, the Vaccine and Gene Therapy Institute, Oregon Health and Science University, Beaverton, Oregon 97006, the National Institute for Biological Standards and Control, Herts EN6 3QG, United Kingdom, the Cancer Research UK Institute for Cancer Studies, University of Birmingham, Birmingham B15 2TT, United Kingdom, INSERM MTi, University Paris Diderot, Paris 75013, France, and the Department of Child Health, Cardiff University, Wales School of Medicine, Cardiff CF14 4XN, United Kingdom
| | - Nicola Rose
- Department of Laboratory Medicine, Lund University, University Hospital Malmo¨, Malmo¨ S-20502, Sweden, the Vaccine and Gene Therapy Institute, Oregon Health and Science University, Beaverton, Oregon 97006, the National Institute for Biological Standards and Control, Herts EN6 3QG, United Kingdom, the Cancer Research UK Institute for Cancer Studies, University of Birmingham, Birmingham B15 2TT, United Kingdom, INSERM MTi, University Paris Diderot, Paris 75013, France, and the Department of Child Health, Cardiff University, Wales School of Medicine, Cardiff CF14 4XN, United Kingdom
| | - David J Blackbourn
- Department of Laboratory Medicine, Lund University, University Hospital Malmo¨, Malmo¨ S-20502, Sweden, the Vaccine and Gene Therapy Institute, Oregon Health and Science University, Beaverton, Oregon 97006, the National Institute for Biological Standards and Control, Herts EN6 3QG, United Kingdom, the Cancer Research UK Institute for Cancer Studies, University of Birmingham, Birmingham B15 2TT, United Kingdom, INSERM MTi, University Paris Diderot, Paris 75013, France, and the Department of Child Health, Cardiff University, Wales School of Medicine, Cardiff CF14 4XN, United Kingdom
| | - Bruno O Villoutreix
- Department of Laboratory Medicine, Lund University, University Hospital Malmo¨, Malmo¨ S-20502, Sweden, the Vaccine and Gene Therapy Institute, Oregon Health and Science University, Beaverton, Oregon 97006, the National Institute for Biological Standards and Control, Herts EN6 3QG, United Kingdom, the Cancer Research UK Institute for Cancer Studies, University of Birmingham, Birmingham B15 2TT, United Kingdom, INSERM MTi, University Paris Diderot, Paris 75013, France, and the Department of Child Health, Cardiff University, Wales School of Medicine, Cardiff CF14 4XN, United Kingdom
| | - O Brad Spiller
- Department of Laboratory Medicine, Lund University, University Hospital Malmo¨, Malmo¨ S-20502, Sweden, the Vaccine and Gene Therapy Institute, Oregon Health and Science University, Beaverton, Oregon 97006, the National Institute for Biological Standards and Control, Herts EN6 3QG, United Kingdom, the Cancer Research UK Institute for Cancer Studies, University of Birmingham, Birmingham B15 2TT, United Kingdom, INSERM MTi, University Paris Diderot, Paris 75013, France, and the Department of Child Health, Cardiff University, Wales School of Medicine, Cardiff CF14 4XN, United Kingdom
| | - Anna M Blom
- Department of Laboratory Medicine, Lund University, University Hospital Malmo¨, Malmo¨ S-20502, Sweden, the Vaccine and Gene Therapy Institute, Oregon Health and Science University, Beaverton, Oregon 97006, the National Institute for Biological Standards and Control, Herts EN6 3QG, United Kingdom, the Cancer Research UK Institute for Cancer Studies, University of Birmingham, Birmingham B15 2TT, United Kingdom, INSERM MTi, University Paris Diderot, Paris 75013, France, and the Department of Child Health, Cardiff University, Wales School of Medicine, Cardiff CF14 4XN, United Kingdom.
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27
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Kaposi's sarcoma-associated herpesvirus gH/gL: glycoprotein export and interaction with cellular receptors. J Virol 2008; 83:396-407. [PMID: 18945775 DOI: 10.1128/jvi.01170-08] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The attachment, entry, and fusion of Kaposi's sarcoma-associated herpesvirus (KSHV) with target cells are mediated by complex machinery containing, among others, viral glycoprotein H (gH) and its alleged chaperone, gL. We observed that KSHV gH, in contrast to its homologues in several other herpesviruses, is transported to the cytoplasm membrane independently from gL, but not vice versa. Mutational analysis revealed that the N terminus of gH is sufficient for gL interaction. However, the entire extracellular part of gH is required for efficient gL secretion. The soluble ectodomain of gH was sufficient to interact with the surfaces of potential target cells in a heparin-dependent manner, and binding was further enhanced by coexpression of gL. Surface plasmon resonance revealed a remarkably high affinity of gH for glycosaminoglycans. Heparan sulfate (HS) proteoglycans of the syndecan family act as cellular receptors for the gH/gL complex. They promoted KSHV infection, and expression of gH/gL on target cells inhibited subsequent KSHV infection. Whereas gH alone was able to bind to HS, we observed that only the gH/gL complex adhered to heparan sulfate-negative cells at lamellipodium-like structures.
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28
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Immune evasion in Kaposi's sarcoma-associated herpes virus associated oncogenesis. Semin Cancer Biol 2008; 18:423-36. [PMID: 18948197 DOI: 10.1016/j.semcancer.2008.09.003] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2008] [Accepted: 09/26/2008] [Indexed: 12/11/2022]
Abstract
A hallmark of herpesviruses is a lifelong persistent infection, which often leads to diseases upon immune suppression of infected host. Kaposi's sarcoma-associated herpesvirus (KSHV), also known as human herpesvirus 8 (HHV8), is etiologically linked to the development of Kaposi's sarcoma (KS), primary effusion lymphoma (PEL), and Multicentric Castleman's disease (MCD). In order to establish a persistent infection, KSHV dedicates a large portion of its genomic information to sabotage almost every aspect of host immune system. Thus, understanding the interplay between KSHV and the host immune system is important in not only unraveling the complexities of viral persistence and pathogenesis, but also discovering novel therapeutic targets. This review summarizes current knowledge of host immune evasion strategies of KSHV and their contributions to KSHV-associated diseases.
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Willett BJ, McMonagle EL, Logan N, Samman A, Hosie MJ. A single site for N-linked glycosylation in the envelope glycoprotein of feline immunodeficiency virus modulates the virus-receptor interaction. Retrovirology 2008; 5:77. [PMID: 18721458 PMCID: PMC2563026 DOI: 10.1186/1742-4690-5-77] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2008] [Accepted: 08/22/2008] [Indexed: 11/10/2022] Open
Abstract
Feline immunodeficiency virus (FIV) targets helper T cells by attachment of the envelope glycoprotein (Env) to CD134, a subsequent interaction with CXCR4 then facilitating the process of viral entry. As the CXCR4 binding site is not exposed until CD134-binding has occurred then the virus is protected from neutralising antibodies targeting the CXCR4-binding site on Env. Prototypic FIV vaccines based on the FL4 strain of FIV contain a cell culture-adapted strain of FIV Petaluma, a CD134-independent strain of FIV that interacts directly with CXCR4. In addition to a characteristic increase in charge in the V3 loop homologue of FIVFL4, we identified two mutations in potential sites for N-linked glycosylation in the region of FIV Env analogous to the V1–V2 region of HIV and SIV Env, T271I and N342Y. When these mutations were introduced into the primary GL8 and CPG41 strains of FIV, the T271I mutation was found to alter the nature of the virus-CD134 interaction; primary viruses carrying the T271I mutation no longer required determinants in cysteine-rich domain (CRD) 2 of CD134 for viral entry. The T271I mutation did not confer CD134-independent infection upon GL8 or CPG41, nor did it increase the affinity of the CXCR4 interaction, suggesting that the principal effect was targeted at reducing the complexity of the Env-CD134 interaction.
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Affiliation(s)
- Brian J Willett
- Retrovirus Research Laboratory, Institute of Comparative Medicine, Faculty of Veterinary Medicine, University of Glasgow, Bearsden Road, Glasgow, G61 1QH, UK.
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Okroj M, Spiller OB, Korodi Z, Tedeschi R, Dillner J, Blom AM. Antibodies against Kaposi sarcoma-associated herpes virus (KSHV) complement control protein (KCP) in infected individuals. Vaccine 2007; 25:8102-9. [PMID: 17964697 DOI: 10.1016/j.vaccine.2007.09.046] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2007] [Revised: 09/17/2007] [Accepted: 09/20/2007] [Indexed: 10/22/2022]
Abstract
Kaposi sarcoma-associated herpesvirus (KSHV) is the most important etiopathological factor of Kaposi's sarcoma (KS) and some specific types of malignant lymphomas. One of the viral lytic genes encodes the KSHV complement control protein (KCP), which functionally mimics human complement inhibitors. Although this protein provides an advantage for evading the complement attack, it can serve as target for adaptive immune response. Herein, we identified anti-KCP IgG antibodies in patients with KS and KSHV-related lymphomas. KCP-specific antibodies were only detected in sera of those patients who had high titres of antibodies against lytic or latent KSHV antigens. Complement control protein domain 2 (CCP2) was found to be the most immunogenic part of the KCP protein. Furthermore, pre-incubation of KCP-expressing CHO cells with patient sera containing anti-KCP antibodies resulted in an increased complement deposition when incubated with human serum.
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Affiliation(s)
- Marcin Okroj
- Department of Laboratory Medicine, Lund University, University Hospital Malmö, S-205 02 Malmö, Sweden
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Blom AM, Mark L, Spiller OB. Viral Heparin-Binding Complement Inhibitors – A Recurring Theme. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2007; 598:105-25. [PMID: 17892208 DOI: 10.1007/978-0-387-71767-8_9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- Anna M Blom
- Lund University, Department of Laboratory Medicine, The Wallenberg Laboratory, 4th floor, Malmö University Hospital, entrance 46, S-205 02 Malmö, Sweden
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Mark L, Proctor DG, Blackbourn DJ, Blom AM, Spiller OB. Separation of decay-accelerating and cofactor functional activities of Kaposi's sarcoma-associated herpesvirus complement control protein using monoclonal antibodies. Immunology 2007; 123:228-38. [PMID: 17764451 PMCID: PMC2433302 DOI: 10.1111/j.1365-2567.2007.02692.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
Complement is an essential part of the innate immune system, which clears pathogens without requirement for previous exposure, although it also greatly enhances the efficacy and response of the cellular and humoral immune systems. Kaposi's sarcoma-associated herpesvirus (KSHV) is the most recently identified human herpesvirus and the likely aetiological agent of Kaposi's sarcoma, primary effusion lymphoma and multicentric Castleman's disease. We previously reported that the KSHV complement control protein (KCP) was expressed on infected cells and virions, and could inhibit complement through decay-accelerating activity (DAA) of the classical C3 convertase and cofactor activity (CFA) for factor I (FI)-mediated degradation of C4b and C3b, as well as acting as an attachment factor for binding to heparan sulphate on permissive cells. Here, we determined the ability of a panel of monoclonal anti-KCP antibodies to block KCP functions relative to their recognized epitopes, as determined through binding to recombinant KCP containing large (entire domain) or small (2-3 amino acid residue) alterations. One antibody recognizing complement control protein (CCP) domain 1 blocked heparin binding, DAA and C4b CFA, but was poor at blocking C3b CFA, while a second antibody recognizing CCP4 blocked C3b CFA and 80% DAA, but not C4b CFA or heparan sulphate binding. Two antibodies recognizing CCP2 and CCP3 were capable of blocking C3b and C4b CFA and heparan sulphate binding, but only one could inhibit DAA. These results show that, while KCP is a multifunctional protein, these activities do not completely overlap and can be isolated through incubation with monoclonal antibodies.
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Affiliation(s)
- Linda Mark
- Medical Protein Chemistry Group, Lund University, University Hospital Malmö, Malmö, Sweden
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Willett BJ, McMonagle EL, Logan N, Spiller OB, Schneider P, Hosie MJ. Probing the interaction between feline immunodeficiency virus and CD134 by using the novel monoclonal antibody 7D6 and the CD134 (Ox40) ligand. J Virol 2007; 81:9665-79. [PMID: 17609274 PMCID: PMC2045395 DOI: 10.1128/jvi.01020-07] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The feline immunodeficiency virus (FIV) targets activated CD4-positive helper T cells preferentially, inducing an AIDS-like immunodeficiency in its natural host species, the domestic cat. The primary receptor for FIV is CD134, a member of the tumor necrosis factor receptor superfamily, and all primary viral strains tested to date use CD134 for infection. We examined the expression of CD134 in the cat using a novel anti-feline CD134 monoclonal antibody (MAb), 7D6, and showed that as in rats and humans, CD134 expression is restricted tightly to CD4+, and not CD8+, T cells, consistent with the selective targeting of these cells by FIV. However, FIV is also macrophage tropic, and in chronic infection the viral tropism broadens to include B cells and CD8+ T cells. Using 7D6, we revealed CD134 expression on a B220-positive (B-cell) population and on cultured macrophages but not peripheral blood monocytes. Moreover, macrophage CD134 expression and FIV infection were enhanced by activation in response to bacterial lipopolysaccharide. Consistent with CD134 expression on human and murine T cells, feline CD134 was abundant on mitogen-stimulated CD4+ T cells, with weaker expression on CD8+ T cells, concordant with the expansion of FIV into CD8+ T cells with progression of the infection. The interaction between FIV and CD134 was probed using MAb 7D6 and soluble CD134 ligand (CD134L), revealing strain-specific differences in sensitivity to both 7D6 and CD134L. Infection with isolates such as PPR and B2542 was inhibited well by both 7D6 and CD134L, suggesting a lower affinity of interaction. In contrast, GL8, CPG, and NCSU were relatively refractory to inhibition by both 7D6 and CD134L and, accordingly, may have a higher-affinity interaction with CD134, permitting infection of cells where CD134 levels are limiting.
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Affiliation(s)
- Brian J Willett
- Retrovirus Research Laboratory, Institute of Comparative Medicine, Faculty of Veterinary Medicine, University of Glasgow, Bearsden Road, Glasgow, United Kingdom.
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Abstract
To efficiently establish a persistent infection, Kaposi's sarcoma-associated herpesvirus (KSHV; also known as HHV8) dedicates a large amount of its coding potential to produce proteins that antagonize the immune system of its host. These viral immunomodulators interfere with both the innate and adaptive immune responses and most of them are homologous to cellular proteins, suggesting that they have been pirated from the host during viral evolution. In this Review, I present recent advances in the understanding of immune evasion by KSHV, with a particular focus on the virally encoded modulators of immune responses that are unique to this virus.
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Affiliation(s)
- Laurent Coscoy
- Department of Molecular and Cell Biology, University of California, Berkeley, California 94720, USA.
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Mark L, Spiller OB, Okroj M, Chanas S, Aitken JA, Wong SW, Damania B, Blom AM, Blackbourn DJ. Molecular characterization of the rhesus rhadinovirus (RRV) ORF4 gene and the RRV complement control protein it encodes. J Virol 2007; 81:4166-76. [PMID: 17287274 PMCID: PMC1866137 DOI: 10.1128/jvi.02069-06] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The diversity of viral strategies to modulate complement activation indicates that this component of the immune system has significant antiviral potential. One example is the Kaposi's sarcoma-associated herpesvirus (KSHV) complement control protein (KCP), which inhibits progression of the complement cascade. Rhesus rhadinovirus (RRV), like KSHV, is a member of the subfamily Gammaherpesvirinae and currently provides the only in vivo model of KSHV pathobiology in primates. In the present study, we characterized the KCP homologue encoded by RRV, RRV complement control protein (RCP). Two strains of RRV have been sequenced to date (H26-95 and 17577), and the RCPs they encode differ substantially in structure: RCP from strain H26-95 has four complement control protein (CCP) domains, whereas RCP from strain 17577 has eight CCP domains. Transcriptional analyses of the RCP gene (ORF4, referred to herein as RCP) in infected rhesus macaque fibroblasts mapped the ends of the transcripts of both strains. They revealed that H26-95 encodes a full-length, unspliced RCP transcript, while 17577 RCP generates a full-length unspliced mRNA and two alternatively spliced transcripts. Western blotting confirmed that infected cells express RCP, and immune electron microscopy disclosed this protein on the surface of RRV virions. Functional studies of RCP encoded by both RRV strains revealed their ability to suppress complement activation by the classical (antibody-mediated) pathway. These data provide the foundation for studies into the biological significance of gammaherpesvirus complement regulatory proteins in a tractable, non-human primate model.
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Affiliation(s)
- Linda Mark
- Department of Laboratory Medicine, Lund University, University Hospital Malmö, Sweden
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Greene W, Kuhne K, Ye F, Chen J, Zhou F, Lei X, Gao SJ. Molecular biology of KSHV in relation to AIDS-associated oncogenesis. Cancer Treat Res 2007; 133:69-127. [PMID: 17672038 PMCID: PMC2798888 DOI: 10.1007/978-0-387-46816-7_3] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
KSHV has been established as the causative agent of KS, PEL, and MCD, malignancies occurring more frequently in AIDS patients. The aggressive nature of KSHV in the context of HIV infection suggests that interactions between the two viruses enhance pathogenesis. KSHV latent infection and lytic reactivation are characterized by distinct gene expression profiles, and both latency and lytic reactivation seem to be required for malignant progression. As a sophisticated oncogenic virus, KSHV has evolved to possess a formidable repertoire of potent mechanisms that enable it to target and manipulate host cell pathways, leading to increased cell proliferation, increased cell survival, dysregulated angiogenesis, evasion of immunity, and malignant progression in the immunocompromised host. Worldwide, approximately 40.3 million people are currently living with HIV infection. Of these, a significant number are coinfected with KSHV. The complex interplay between the two viruses dramatically elevates the risk for development of KSHV-induced malignancies, KS, PEL, and MCD. Although HAART significantly reduces HIV viral load, the entire T-cell repertoire and immune function may not be completely restored. In fact, clinically significant immune deficiency is not necessary for the induction of KSHV-related malignancy. Because of variables such as lack of access to therapy noncompliance with prescribed treatment, failure to respond to treatment and the development of drug-resistant strains of HIV, KSHV-induced malignancies will continue to present as major health concerns.
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Affiliation(s)
- Whitney Greene
- Tiumor Virology Program, Children's Cancer Research Institute, Department of Pediatrics, The University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
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Mark L, Spiller OB, Villoutreix BO, Blom AM. Kaposi's sarcoma-associated herpes virus complement control protein: KCP--complement inhibition and more. Mol Immunol 2006; 44:11-22. [PMID: 16905191 DOI: 10.1016/j.molimm.2006.06.018] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2006] [Revised: 06/21/2006] [Accepted: 06/22/2006] [Indexed: 01/06/2023]
Abstract
The complement system is an important part of innate immunity providing immediate protection against pathogens without a need for previous exposure, as well as priming the adaptive immune response through opsonisation, leukocyte recruitment and enhancing humoral immune responses. Its importance is not only shown through recurring fulminant infections in individuals with complement component deficiencies, but also through the many complement evasion strategies discovered for a wide range of infectious microbes (including acquisition of endogenous host complement inhibitors and expression of own homologues). Knowledge of these mechanisms at a molecular level may aid development of vaccines and novel therapeutic strategies. Here, we review the structure-function studies of the membrane-bound complement inhibitor KCP that is expressed on the surface of Kaposi's sarcoma-associated herpesvirus (KSHV) virions and infected cells. KCP accelerates the decay of classical C3 convertase and induces the degradation of activated complement factors C4b and C3b by a serine proteinase, factor I. Molecular modeling and site-directed mutagenesis have identified sites on the surface of KCP required for complement inhibition and support the hypothesis that KCP has evolved to mimic the structure and function of endogenous human inhibitors. KCP additionally enhances virion binding to permissive cells through a heparin/heparan sulfate-binding site located at the N-terminus of the protein.
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Affiliation(s)
- Linda Mark
- Department of Laboratory Medicine, Lund University, University Hospital Malmö, Malmö S-20502, Sweden
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Rezaee SAR, Cunningham C, Davison AJ, Blackbourn DJ. Kaposi's sarcoma-associated herpesvirus immune modulation: an overview. J Gen Virol 2006; 87:1781-1804. [PMID: 16760382 DOI: 10.1099/vir.0.81919-0] [Citation(s) in RCA: 98] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Kaposi's sarcoma-associated herpesvirus (KSHV) is the most recently discovered human herpesvirus. It is the aetiological agent of Kaposi's sarcoma (KS), a tumour frequently affecting AIDS patients not receiving treatment. KSHV is also a likely cause of two lymphoproliferative diseases: multicentric Castleman's disease and primary effusion lymphoma. The study of KSHV offers exciting challenges for understanding the mechanisms of virus pathogenesis, including those involved in establishing infection and dissemination in the host. To facilitate these processes, approximately one-quarter of KSHV genes encode cellular homologues or unique proteins that have immunomodulatory roles in cytokine production, apoptosis, cell signalling and the immunological synapse. The activities of these molecules are considered in the present review and the positions of their genes are mapped from a complete KSHV genome sequence derived from a KS biopsy. The understanding gained enables the significance of different components of the immune response in protection against KSHV infection to be evaluated. It also helps to unravel the complexities of cellular and immunological pathways and offers the potential for exploiting viral immunomodulators and derivatives in disease therapy.
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Affiliation(s)
- S A Rahim Rezaee
- Cancer Research UK Institute for Cancer Studies, University of Birmingham, Vincent Drive, Birmingham B15 2TT, UK
| | | | | | - David J Blackbourn
- Cancer Research UK Institute for Cancer Studies, University of Birmingham, Vincent Drive, Birmingham B15 2TT, UK
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Järviluoma A, Ojala PM. Cell signaling pathways engaged by KSHV. Biochim Biophys Acta Rev Cancer 2006; 1766:140-58. [PMID: 16828973 DOI: 10.1016/j.bbcan.2006.05.001] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2006] [Revised: 05/11/2006] [Accepted: 05/13/2006] [Indexed: 11/23/2022]
Abstract
Kaposi's sarcoma herpesvirus (KSHV) is the eighth human herpesvirus discovered in 1994 from Kaposi's sarcoma lesion of an AIDS patient. The strong molecular and epidemiological links associating KSHV with Kaposi's sarcoma and certain lymphoproliferative disorders indicate that KSHV is required for the development of these malignancies. Although KSHV is equipped to manipulate and deregulate several cellular signaling pathways, it is not yet understood how this leads to cell transformation. Profound understanding of the interplay of viral and cellular factors in KSHV-infected cells will provide valuable information on the mechanisms of viral tumorigenesis and enable development of efficient targeted therapies for virus-induced cancers. This review focuses on the cellular signaling pathways that KSHV gene products impinge on and discusses their putative contribution to tumorigenesis.
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Affiliation(s)
- Annika Järviluoma
- Molecular Cancer Biology Program, Institute of Biomedicine, Biomedicum Helsinki, P.O. Box 63, FIN-00014-University of Helsinki, Finland
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