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Lujan E, Zhang I, Garon AC, Liu F. The Interactions of the Complement System with Human Cytomegalovirus. Viruses 2024; 16:1171. [PMID: 39066333 PMCID: PMC11281448 DOI: 10.3390/v16071171] [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: 06/05/2024] [Revised: 07/02/2024] [Accepted: 07/15/2024] [Indexed: 07/28/2024] Open
Abstract
The complement system is an evolutionarily ancient component of innate immunity that serves as an important first line of defense against pathogens, including viruses. In response to infection, the complement system can be activated by three distinct yet converging pathways (classical, lectin, and alternative) capable of engaging multiple antiviral host responses to confront acute, chronic, and recurrent viral infections. Complement can exert profound antiviral effects via multiple mechanisms including the induction of inflammation and chemotaxis to sites of infection, neutralization/opsonization of viruses and virally infected cells, and it can even shape adaptive immune responses. With millions of years of co-evolution and the ability to establish life-long infections, herpesviruses have evolved unique mechanisms to counter complement-mediated antiviral defenses, thus enabling their survival and replication within humans. This review aims to comprehensively summarize how human herpesviruses engage with the complement system and highlight our understanding of the role of complement in human cytomegalovirus (HCMV) infection, immunity, and viral replication. Herein we describe the novel and unorthodox roles of complement proteins beyond their roles in innate immunity and discuss gaps in knowledge and future directions of complement and HCMV research.
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Affiliation(s)
- Eduardo Lujan
- Program in Comparative Biochemistry, University of California, Berkeley, CA 94720, USA
| | - Isadora Zhang
- School of Public Health, University of California, Berkeley, CA 94720, USA
| | - Andrea Canto Garon
- Program in Comparative Biochemistry, University of California, Berkeley, CA 94720, USA
| | - Fenyong Liu
- Program in Comparative Biochemistry, University of California, Berkeley, CA 94720, USA
- School of Public Health, University of California, Berkeley, CA 94720, USA
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2
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Kumar P, Chaudhary B, Yadav N, Devi S, Pareek A, Alla S, Kajal F, Nowrouzi-Kia B, Chattu VK, Gupta MM. Recent Advances in Research and Management of Human Monkeypox Virus: An Emerging Global Health Threat. Viruses 2023; 15:v15040937. [PMID: 37112916 PMCID: PMC10146223 DOI: 10.3390/v15040937] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Revised: 04/01/2023] [Accepted: 04/07/2023] [Indexed: 04/29/2023] Open
Abstract
In 2003, the United States saw an epidemic of monkeypox that was later traced back to rodents of West Africa infected with the monkeypox virus (MPXV). Disease in the United States seemed less severe than the smallpox-like disease in the Democratic Republic of the Congo (DRC). In this study, researchers analyzed data from Central Africa: two distinct MPXV clades were confirmed by sequencing the genomes of MPXV isolates from Western Africa, the United States, and Central Africa. By comparing open reading frames across MPXV clades, scientists can infer which virus proteins might account for the observed variation in pathogenicity in humans. Monkeypox can be prevented and controlled with a better understanding of MPXV's molecular etiology and epidemiological and clinical features. In light of the current outbreaks worldwide, we provide updated information on monkeypox for medical professionals in this review.
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Affiliation(s)
- Parveen Kumar
- Shri Ram College of Pharmacy, Karnal 132116, Haryana, India
| | - Benu Chaudhary
- Guru Gobind Singh College of Pharmacy, Yamunanagar 135001, Haryana, India
| | - Nishant Yadav
- B.S. Anangpuria Institute of Pharmacy, Faridabad 121004, Haryana, India
- Chitkara College of Pharmacy, Chitkara University, Rajpura 140401, Punjab, India
| | - Sushma Devi
- Chitkara College of Pharmacy, Chitkara University, Rajpura 140401, Punjab, India
| | - Ashutosh Pareek
- Department of Pharmacy, Banasthali Vidyapith, Banasthali 304022, Rajasthan, India
| | - Sujatha Alla
- Department of Engineering Management & Systems Engineering, Frank Batten College of Engineering, Old Dominion University, Norfolk, VA 23529, USA
- Center for Technology and Innovations, Global Health Research and Innovations Canada, Toronto, ON M1J 2W8, Canada
| | - Fnu Kajal
- Department of Health Promotion Sciences, University of Arizona, Tucson, AZ 85719, USA
| | - Behdin Nowrouzi-Kia
- Department of Occupational Science and Occupational Therapy, Temerty Faculty of Medicine, University of Toronto, Toronto, ON M5G 1V7, Canada
| | - Vijay Kumar Chattu
- Department of Occupational Science and Occupational Therapy, Temerty Faculty of Medicine, University of Toronto, Toronto, ON M5G 1V7, Canada
- Department of Community Medicine, Faculty of Medicine, Datta Meghe Institute of Medical Sciences, Wardha 442107, Maharashtra, India
- Center for Transdisciplinary Research, Saveetha Dental College, Saveetha Institute of Medical and Technical Sciences, Saveetha University, Chennai 600077, Tamil Nadu, India
| | - Madan Mohan Gupta
- School of Pharmacy, Faculty of Medical Sciences, The University of the West Indies, St. Augustine 3303, Trinidad and Tobago
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3
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Abstract
Monkeypox is a zoonotic disease, presenting with fever, lymphadenopathy and vesicular-pustular skin lesions, that historically has rarely been reported outside the endemic regions of Central and West Africa. It was previously thought that human-to-human transmission was too low to sustain spread. During 2022, the number of cases of monkeypox, caused by clade II, rose rapidly globally, predominantly among men who have sex with men. In previous outbreaks with monkeypox clade 1 in endemic areas, children were disproportionately more affected with higher morbidity and mortality. It is unclear whether children are at similarly higher risk from monkeypox clade II. Nonetheless, children and pregnant women are considered high-risk groups and antiviral treatment should be considered for those affected. While smallpox vaccination offers good protection against monkeypox, the duration of protection is unknown, and infection occurs in vaccinated individuals. Should the current outbreak spread to children, authorities should be prepared to rapidly implement vaccination for children. In this review, we summarize epidemiological and clinical features, as well as the pathogenesis, treatment, and prevention options for monkeypox with a focus on considerations for children.
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4
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Lum FM, Torres-Ruesta A, Tay MZ, Lin RTP, Lye DC, Rénia L, Ng LFP. Monkeypox: disease epidemiology, host immunity and clinical interventions. Nat Rev Immunol 2022; 22:597-613. [PMID: 36064780 PMCID: PMC9443635 DOI: 10.1038/s41577-022-00775-4] [Citation(s) in RCA: 184] [Impact Index Per Article: 92.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/09/2022] [Indexed: 12/11/2022]
Abstract
Monkeypox virus (MPXV), which causes disease in humans, has for many years been restricted to the African continent, with only a handful of sporadic cases in other parts of the world. However, unprecedented outbreaks of monkeypox in non-endemic regions have recently taken the world by surprise. In less than 4 months, the number of detected MPXV infections has soared to more than 48,000 cases, recording a total of 13 deaths. In this Review, we discuss the clinical, epidemiological and immunological features of MPXV infections. We also highlight important research questions and new opportunities to tackle the ongoing monkeypox outbreak. In this Review, Ng and colleagues examine the clinical, epidemiological and immunological aspects of monkeypox virus (MPXV) infections, with a focus on mechanisms of host immunity to MPXV. The authors also consider the unique epidemiological and pathological characteristics of the current non-endemic outbreak of the virus and discuss vaccines, therapeutics and outstanding research questions.
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Affiliation(s)
- Fok-Moon Lum
- A*STAR Infectious Diseases Labs, Agency for Science, Technology and Research (A*STAR), Singapore, Singapore
| | - Anthony Torres-Ruesta
- A*STAR Infectious Diseases Labs, Agency for Science, Technology and Research (A*STAR), Singapore, Singapore
| | - Matthew Z Tay
- A*STAR Infectious Diseases Labs, Agency for Science, Technology and Research (A*STAR), Singapore, Singapore
| | - Raymond T P Lin
- National Public Health Laboratory, Singapore, Singapore.,National Centre for Infectious Diseases, Singapore, Singapore.,Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - David C Lye
- National Centre for Infectious Diseases, Singapore, Singapore.,Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore.,Tan Tock Seng Hospital, Singapore, Singapore.,Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Laurent Rénia
- A*STAR Infectious Diseases Labs, Agency for Science, Technology and Research (A*STAR), Singapore, Singapore.,Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore.,School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
| | - Lisa F P Ng
- A*STAR Infectious Diseases Labs, Agency for Science, Technology and Research (A*STAR), Singapore, Singapore. .,National Institute of Health Research, Health Protection Research Unit in Emerging and Zoonotic Infections, University of Liverpool, Liverpool, UK. .,Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool, UK.
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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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Chelkha N, Levasseur A, La Scola B, Colson P. Host-virus interactions and defense mechanisms for giant viruses. Ann N Y Acad Sci 2020; 1486:39-57. [PMID: 33090482 DOI: 10.1111/nyas.14469] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2020] [Revised: 06/28/2020] [Accepted: 07/26/2020] [Indexed: 12/26/2022]
Abstract
Giant viruses, with virions larger than 200 nm and genomes larger than 340 kilobase pairs, modified the now outdated perception of the virosphere. With virions now reported reaching up to 1.5 μm in size and genomes of up to 2.5 Mb encoding components shared with cellular life forms, giant viruses exhibit a complexity similar to microbes, such as bacteria and archaea. Here, we review interactions of giant viruses with their hosts and defense strategies of giant viruses against their hosts and coinfecting microorganisms or virophages. We also searched by comparative genomics for homologies with proteins described or suspected to be involved in defense mechanisms. Our search reveals that natural immunity and apoptosis seem to be crucial components of the host defense against giant virus infection. Conversely, giant viruses possess methods of hijacking host functions to counteract cellular antiviral responses. In addition, giant viruses may encode other unique and complex pathways to manipulate the host machinery and eliminate other competing microorganisms. Notably, giant viruses have evolved defense mechanisms against their virophages and they might trigger defense systems against other viruses through sequence integration. We anticipate that comparative genomics may help identifying genes involved in defense strategies of both giant viruses and their hosts.
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Affiliation(s)
- Nisrine Chelkha
- Aix-Marseille University, Institut de Recherche pour le Développement (IRD), Assistance Publique - Hôpitaux de Marseille (AP-HM), Microbes Evolution Phylogeny and Infections (MEPHI), Marseille, France
| | - Anthony Levasseur
- Aix-Marseille University, Institut de Recherche pour le Développement (IRD), Assistance Publique - Hôpitaux de Marseille (AP-HM), Microbes Evolution Phylogeny and Infections (MEPHI), Marseille, France
- IHU Méditerranée Infection, Marseille, France
| | - Bernard La Scola
- Aix-Marseille University, Institut de Recherche pour le Développement (IRD), Assistance Publique - Hôpitaux de Marseille (AP-HM), Microbes Evolution Phylogeny and Infections (MEPHI), Marseille, France
- IHU Méditerranée Infection, Marseille, France
| | - Philippe Colson
- Aix-Marseille University, Institut de Recherche pour le Développement (IRD), Assistance Publique - Hôpitaux de Marseille (AP-HM), Microbes Evolution Phylogeny and Infections (MEPHI), Marseille, France
- IHU Méditerranée Infection, Marseille, France
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7
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Agrawal P, Sharma S, Pal P, Ojha H, Mullick J, Sahu A. The imitation game: a viral strategy to subvert the complement system. FEBS Lett 2020; 594:2518-2542. [DOI: 10.1002/1873-3468.13856] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Revised: 03/10/2020] [Accepted: 05/23/2020] [Indexed: 11/09/2022]
Affiliation(s)
- Palak Agrawal
- Complement Biology Laboratory National Centre for Cell Science S. P. Pune University Campus Ganeshkhind Pune 411007 India
| | - Samriddhi Sharma
- Complement Biology Laboratory National Centre for Cell Science S. P. Pune University Campus Ganeshkhind Pune 411007 India
| | - Pradipta Pal
- Complement Biology Laboratory National Centre for Cell Science S. P. Pune University Campus Ganeshkhind Pune 411007 India
| | - Hina Ojha
- Complement Biology Laboratory National Centre for Cell Science S. P. Pune University Campus Ganeshkhind Pune 411007 India
| | - Jayati Mullick
- 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 Ganeshkhind Pune 411007 India
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8
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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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9
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Ojha H, Ghosh P, Singh Panwar H, Shende R, Gondane A, Mande SC, Sahu A. Spatially conserved motifs in complement control protein domains determine functionality in regulators of complement activation-family proteins. Commun Biol 2019; 2:290. [PMID: 31396570 PMCID: PMC6683126 DOI: 10.1038/s42003-019-0529-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2019] [Accepted: 07/03/2019] [Indexed: 12/14/2022] Open
Abstract
Regulation of complement activation in the host cells is mediated primarily by the regulators of complement activation (RCA) family proteins that are formed by tandemly repeating complement control protein (CCP) domains. Functional annotation of these proteins, however, is challenging as contiguous CCP domains are found in proteins with varied functions. Here, by employing an in silico approach, we identify five motifs which are conserved spatially in a specific order in the regulatory CCP domains of known RCA proteins. We report that the presence of these motifs in a specific pattern is sufficient to annotate regulatory domains in RCA proteins. We show that incorporation of the lost motif in the fourth long-homologous repeat (LHR-D) in complement receptor 1 regains its regulatory activity. Additionally, the motif pattern also helped annotate human polydom as a complement regulator. Thus, we propose that the motifs identified here are the determinants of functionality in RCA proteins.
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Affiliation(s)
- Hina Ojha
- Complement Biology Laboratory, National Centre for Cell Science, S. P. Pune University campus, Pune, 411007 India
| | - Payel Ghosh
- Bioinformatics Centre, S. P. Pune University, Pune, 411007 India
| | - Hemendra Singh Panwar
- Complement Biology Laboratory, National Centre for Cell Science, S. P. Pune University campus, Pune, 411007 India
| | - Rajashri Shende
- Complement Biology Laboratory, National Centre for Cell Science, S. P. Pune University campus, Pune, 411007 India
| | | | - Shekhar C. Mande
- Structural Biology Laboratory, National Centre for Cell Science, S. P. Pune University campus, Pune, 411007 India
- Present Address: Council of Scientific and Industrial Research (CSIR), Anusandhan Bhawan, 2 Rafi Marg, New Delhi, 110001 India
| | - Arvind Sahu
- Complement Biology Laboratory, National Centre for Cell Science, S. P. Pune University campus, Pune, 411007 India
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10
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The Virology of Taterapox Virus In Vitro. Viruses 2018; 10:v10090463. [PMID: 30158437 PMCID: PMC6163509 DOI: 10.3390/v10090463] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2018] [Revised: 08/08/2018] [Accepted: 08/16/2018] [Indexed: 11/29/2022] Open
Abstract
Taterapox virus (TATV) is phylogenetically the closest related virus to variola—the etiological agent of smallpox. Despite the similarity, few studies have evaluated the virus. In vivo, TATV can infect several animals but produces an inapparent infection in wild-type mice; however, TATV does cause morbidity and mortality in some immunocompromised strains. We employed in vitro techniques to compare TATV to ectromelia (ECTV) and vaccinia (VACV) viruses. Both ECTV and TATV replicate efficiently in primate cell lines but TATV replicates poorly in murine cells lines. Furthermore, TATV induces cytopathic effects, but to a lesser extent than ECTV, and changes cytoskeletal networks differently than both ECTV and VACV. Bioinformatic studies revealed differences in several immunomodulator open reading frames that could contribute to the reduced virulence of TATV, which were supported by in vitro cytokine assays.
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11
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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: 107] [Impact Index Per Article: 15.3] [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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12
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Abou-El-Hassan H, Zaraket H. Viral-derived complement inhibitors: current status and potential role in immunomodulation. Exp Biol Med (Maywood) 2016; 242:397-410. [PMID: 27798122 DOI: 10.1177/1535370216675772] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The complement system is one of the body's major innate immune defense mechanisms in vertebrates. Its function is to detect foreign bodies and promote their elimination through opsonisation or lysis. Complement proteins play an important role in the immunopathogenesis of several disorders. However, excessive complement activation does not confer more protection but instead leads to several autoimmune and inflammatory diseases. With inappropriate activation of the complement system, activated complement proteins and glycoproteins may damage both healthy and diseased tissues. Development of complement inhibitors represents an effective approach in controlling dysregulated complement activity and reducing disease severity, yet few studies have investigated the nature and role of novel complement inhibitory proteins of viral origin. Viral complement inhibitors have important implications in understanding the importance of complement inhibition and their role as a promising novel therapeutic approach in diseases caused by dysregulated complement function. In this review, we discuss the role and importance of complement inhibitors derived from several viruses in the scope of human inflammatory and autoimmune diseases.
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Affiliation(s)
- Hadi Abou-El-Hassan
- 1 Faculty of Medicine, American University of Beirut Medical Center, Beirut, Lebanon.,2 Center for Infectious Diseases Research, Faculty of Medicine, American University of Beirut, Beirut, Lebanon
| | - Hassan Zaraket
- 2 Center for Infectious Diseases Research, Faculty of Medicine, American University of Beirut, Beirut, Lebanon.,3 Department of Experimental Pathology, Immunology, and Microbiology, Faculty of Medicine, American University of Beirut, Beirut, Lebanon
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13
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14
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Abstract
Viruses have evolved numerous mechanisms to evade the immune response, including proteins that target the function of cytokines. This article provides an overview of the different strategies used by viruses to block the induction of cytokines and immune signals triggered by cytokines. Examples of virus evasion proteins are presented, such as intracellular proteins that block signal transduction and immune activation mechanisms, secreted proteins that mimic cytokines, or viral decoy receptors that inhibit the binding of cytokines to their cognate receptors. Virus-encoded proteins that target cytokines play a major role in immune modulation, and their contributions to viral pathogenesis, promoting virus replication or preventing immunopathology, are discussed.
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15
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Glycosylated and nonglycosylated complement control protein of the lister strain of vaccinia virus. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2014; 21:1330-8. [PMID: 25030055 DOI: 10.1128/cvi.00347-14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The vaccinia virus complement control protein (VCP) is a secreted viral protein that binds the C3b and C4b complement components and inhibits the classic and alternative complement pathways. Previously, we reported that an attenuated smallpox vaccine, LC16m8, which was derived from the Lister strain of vaccinia virus (VV-Lister), expressed a glycosylated form of VCP, whereas published sequence data at that time indicated that the VV-Lister VCP has no motif for N-linked glycosylation. We were interested in determining whether the glycosylation of VCP impairs its biological activity, possibly contributing to the attenuation of LC16m8, and the likely origin of the glycosylated VCP. Expression analysis indicated that VV-Lister contains substrains expressing glycosylated VCP and substrains expressing nonglycosylated VCP. Other strains of smallpox vaccine, as well as laboratory strains of vaccinia virus, all expressed nonglycosylated VCP. Individual Lister virus clones expressing either the glycosylated VCP or the nonglycosylated species were isolated, and partially purified VCP from the isolates were found to be functional equivalents in binding human C3b and C4b complement proteins and inhibiting hemolysis and in immunogenicity. Recombinant vaccinia viruses expressing FLAG-tagged glycosylated VCP (FLAG-VCPg) and nonglycosylated VCP (FLAG-VCP) were constructed based on the Western Reserve strain. Purified FLAG-VCP and FLAG-VCPg bind human C3b and C4b and blocked complement-mediated hemolysis. Our data suggest that glycosylation did not affect the biological activity of VCP and thus may not have contributed to the attenuation of LC16m8. In addition, the LC16m8 virus likely originated from a substrain of VV-Lister that expresses glycosylated VCP.
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16
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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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17
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Orthopoxvirus genes that mediate disease virulence and host tropism. Adv Virol 2012; 2012:524743. [PMID: 22899927 PMCID: PMC3413996 DOI: 10.1155/2012/524743] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2012] [Accepted: 05/31/2012] [Indexed: 12/16/2022] Open
Abstract
In the course of evolution, viruses have developed various molecular mechanisms to evade the defense reactions of the host organism. When understanding the mechanisms used by viruses to overcome manifold defense systems of the animal organism, represented by molecular factors and cells of the immune system, we would not only comprehend better but also discover new patterns of organization and function of these most important reactions directed against infectious agents. Here, study of the orthopoxviruses pathogenic for humans, such as variola (smallpox), monkeypox, cowpox, and vaccinia viruses, may be most important. Analysis of the experimental data, presented in this paper, allows to infer that variola virus and other orthopoxviruses possess an unexampled set of genes whose protein products efficiently modulate the manifold defense mechanisms of the host organisms compared with the viruses from other families.
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Hudson PN, Self J, Weiss S, Braden Z, Xiao Y, Girgis NM, Emerson G, Hughes C, Sammons SA, Isaacs SN, Damon IK, Olson VA. Elucidating the role of the complement control protein in monkeypox pathogenicity. PLoS One 2012; 7:e35086. [PMID: 22496894 PMCID: PMC3322148 DOI: 10.1371/journal.pone.0035086] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2011] [Accepted: 03/12/2012] [Indexed: 11/19/2022] Open
Abstract
Monkeypox virus (MPXV) causes a smallpox-like disease in humans. Clinical and epidemiological studies provide evidence of pathogenicity differences between two geographically distinct monkeypox virus clades: the West African and Congo Basin. Genomic analysis of strains from both clades identified a ∼10 kbp deletion in the less virulent West African isolates sequenced to date. One absent open reading frame encodes the monkeypox virus homologue of the complement control protein (CCP). This modulatory protein prevents the initiation of both the classical and alternative pathways of complement activation. In monkeypox virus, CCP, also known as MOPICE, is a ∼24 kDa secretory protein with sequence homology to this superfamily of proteins. Here we investigate CCP expression and its role in monkeypox virulence and pathogenesis. CCP was incorporated into the West African strain and removed from the Congo Basin strain by homologous recombination. CCP expression phenotypes were confirmed for both wild type and recombinant monkeypox viruses and CCP activity was confirmed using a C4b binding assay. To characterize the disease, prairie dogs were intranasally infected and disease progression was monitored for 30 days. Removal of CCP from the Congo Basin strain reduced monkeypox disease morbidity and mortality, but did not significantly decrease viral load. The inclusion of CCP in the West African strain produced changes in disease manifestation, but had no apparent effect on disease-associated mortality. This study identifies CCP as an important immuno-modulatory protein in monkeypox pathogenesis but not solely responsible for the increased virulence seen within the Congo Basin clade of monkeypox virus.
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Affiliation(s)
- Paul N Hudson
- Poxvirus and Rabies Branch, Division of High Consequence Pathogens and Pathology, National Center for Emerging and Zoonotic Infectious Diseases and Biotechnology Core Facility Branch, Division of Safety Research, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America.
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19
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It takes a community to raise the prevalence of a zoonotic pathogen. Interdiscip Perspect Infect Dis 2011; 2011:741406. [PMID: 22162687 PMCID: PMC3228346 DOI: 10.1155/2011/741406] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2011] [Revised: 07/18/2011] [Accepted: 09/07/2011] [Indexed: 11/18/2022] Open
Abstract
By definition, zoonotic pathogens are not strict host-species specialists in that they infect humans and at least one nonhuman reservoir species. The majority of zoonotic pathogens infect and are amplified by multiple vertebrate species in nature, each of which has a quantitatively different impact on the distribution and abundance of the pathogen and thus on disease risk. Unfortunately, when new zoonotic pathogens emerge, the dominant response by public health scientists is to search for a few, or even the single, most important reservoirs and to ignore other species that might strongly influence transmission. This focus on the single “primary” reservoir host species can delay biological understanding, and potentially public health interventions as species important in either amplifying or regulating the pathogen are overlooked. Investigating the evolutionary and ecological strategy of newly discovered or emerging pathogens within the community of potential and actual host species will be fruitful to both biological understanding and public health.
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20
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Estep RD, Messaoudi I, O'Connor MA, Li H, Sprague J, Barron A, Engelmann F, Yen B, Powers MF, Jones JM, Robinson BA, Orzechowska BU, Manoharan M, Legasse A, Planer S, Wilk J, Axthelm MK, Wong SW. Deletion of the monkeypox virus inhibitor of complement enzymes locus impacts the adaptive immune response to monkeypox virus in a nonhuman primate model of infection. J Virol 2011; 85:9527-42. [PMID: 21752919 PMCID: PMC3165757 DOI: 10.1128/jvi.00199-11] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2011] [Accepted: 06/26/2011] [Indexed: 01/13/2023] Open
Abstract
Monkeypox virus (MPXV) is an orthopoxvirus closely related to variola virus, the causative agent of smallpox. Human MPXV infection results in a disease that is similar to smallpox and can also be fatal. Two clades of MPXV have been identified, with viruses of the central African clade displaying more pathogenic properties than those within the west African clade. The monkeypox inhibitor of complement enzymes (MOPICE), which is not expressed by viruses of the west African clade, has been hypothesized to be a main virulence factor responsible for increased pathogenic properties of central African strains of MPXV. To gain a better understanding of the role of MOPICE during MPXV-mediated disease, we compared the host adaptive immune response and disease severity following intrabronchial infection with MPXV-Zaire (n = 4), or a recombinant MPXV-Zaire (n = 4) lacking expression of MOPICE in rhesus macaques (RM). Data presented here demonstrate that infection of RM with MPXV leads to significant viral replication in the peripheral blood and lungs and results in the induction of a robust and sustained adaptive immune response against the virus. More importantly, we show that the loss of MOPICE expression results in enhanced viral replication in vivo, as well as a dampened adaptive immune response against MPXV. Taken together, these findings suggest that MOPICE modulates the anti-MPXV immune response and that this protein is not the sole virulence factor of the central African clade of MPXV.
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Affiliation(s)
- Ryan D. Estep
- Vaccine and Gene Therapy Institute, Oregon Health & Science University, Beaverton, Oregon
| | - Ilhem Messaoudi
- Vaccine and Gene Therapy Institute, Oregon Health & Science University, Beaverton, Oregon
- Division of Pathobiology and Immunology, Oregon National Primate Research Center, Beaverton, Oregon
| | - Megan A. O'Connor
- Vaccine and Gene Therapy Institute, Oregon Health & Science University, Beaverton, Oregon
| | - Helen Li
- Vaccine and Gene Therapy Institute, Oregon Health & Science University, Beaverton, Oregon
| | - Jerald Sprague
- Vaccine and Gene Therapy Institute, Oregon Health & Science University, Beaverton, Oregon
| | - Alexander Barron
- Vaccine and Gene Therapy Institute, Oregon Health & Science University, Beaverton, Oregon
| | - Flora Engelmann
- Vaccine and Gene Therapy Institute, Oregon Health & Science University, Beaverton, Oregon
| | - Bonnie Yen
- Vaccine and Gene Therapy Institute, Oregon Health & Science University, Beaverton, Oregon
| | - Michael F. Powers
- Vaccine and Gene Therapy Institute, Oregon Health & Science University, Beaverton, Oregon
| | - John M. Jones
- Vaccine and Gene Therapy Institute, Oregon Health & Science University, Beaverton, Oregon
| | - Bridget A. Robinson
- Vaccine and Gene Therapy Institute, Oregon Health & Science University, Beaverton, Oregon
| | - Beata U. Orzechowska
- Vaccine and Gene Therapy Institute, Oregon Health & Science University, Beaverton, Oregon
| | - Minsha Manoharan
- Vaccine and Gene Therapy Institute, Oregon Health & Science University, Beaverton, Oregon
| | - Alfred Legasse
- Division of Pathobiology and Immunology, Oregon National Primate Research Center, Beaverton, Oregon
| | - Shannon Planer
- Division of Pathobiology and Immunology, Oregon National Primate Research Center, Beaverton, Oregon
| | - Jennifer Wilk
- Division of Animal Resources, Oregon National Primate Research Center, Beaverton, Oregon
| | - Michael K. Axthelm
- Vaccine and Gene Therapy Institute, Oregon Health & Science University, Beaverton, Oregon
- Division of Pathobiology and Immunology, Oregon National Primate Research Center, Beaverton, Oregon
| | - Scott W. Wong
- Vaccine and Gene Therapy Institute, Oregon Health & Science University, Beaverton, Oregon
- Division of Pathobiology and Immunology, Oregon National Primate Research Center, Beaverton, Oregon
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21
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Bernet J, Ahmad M, Mullick J, Panse Y, Singh AK, Parab PB, Sahu A. Disabling complement regulatory activities of vaccinia virus complement control protein reduces vaccinia virus pathogenicity. Vaccine 2011; 29:7435-43. [PMID: 21803094 PMCID: PMC3195257 DOI: 10.1016/j.vaccine.2011.07.062] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2011] [Revised: 06/20/2011] [Accepted: 07/17/2011] [Indexed: 12/02/2022]
Abstract
Poxviruses encode a repertoire of immunomodulatory proteins to thwart the host immune system. One among this array is a homolog of the host complement regulatory proteins that is conserved in various poxviruses including vaccinia (VACV) and variola. The vaccinia virus complement control protein (VCP), which inhibits complement by decaying the classical pathway C3-convertase (decay-accelerating activity), and by supporting inactivation of C3b and C4b by serine protease factor I (cofactor activity), was shown to play a role in viral pathogenesis. However, the role its individual complement regulatory activities impart in pathogenesis, have not yet been elucidated. Here, we have generated monoclonal antibodies (mAbs) that block the VCP functions and utilized them to evaluate the relative contribution of complement regulatory activities of VCP in viral pathogenesis by employing a rabbit intradermal model for VACV infection. Targeting VCP by mAbs that inhibited the decay-accelerating activity as well as cofactor activity of VCP or primarily the cofactor activity of VCP, by injecting them at the site of infection, significantly reduced VACV lesion size. This reduction however was not pronounced when VCP was targeted by a mAb that inhibited only the decay-accelerating activity. Further, the reduction in lesion size by mAbs was reversed when host complement was depleted by injecting cobra venom factor. Thus, our results suggest that targeting VCP by antibodies reduces VACV pathogenicity and that principally the cofactor activity of VCP appears to contribute to the virulence.
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Affiliation(s)
- John Bernet
- National Centre for Cell Science, Pune University Campus, Ganeshkhind, Pune 411007, India
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22
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DeHaven BC, Gupta K, Isaacs SN. The vaccinia virus A56 protein: a multifunctional transmembrane glycoprotein that anchors two secreted viral proteins. J Gen Virol 2011; 92:1971-1980. [PMID: 21715594 DOI: 10.1099/vir.0.030460-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
The vaccinia virus A56 protein was one of the earliest-described poxvirus proteins with an identifiable activity. While originally characterized as a haemagglutinin protein, A56 has other functions as well. The A56 protein is capable of binding two viral proteins, a serine protease inhibitor (K2) and the vaccinia virus complement control protein (VCP), and anchoring them to the surface of infected cells. This is important; while both proteins have biologically relevant functions at the cell surface, neither one can locate there on its own. The A56-K2 complex reduces the amount of virus superinfecting an infected cell and also prevents the formation of syncytia by infected cells; the A56-VCP complex can protect infected cells from complement attack. Deletion of the A56R gene results in varying effects on vaccinia virus virulence. In addition, since the gene encoding the A56 protein is non-essential, it can be used as an insertion point for foreign genes and has been deleted in some viruses that are in clinical development as oncolytic agents.
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Affiliation(s)
- Brian C DeHaven
- Department of Medicine, Division of Infectious Diseases, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA
| | - Kushol Gupta
- Department of Biochemistry & Biophysics and Howard Hughes Medical Institute, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA
| | - Stuart N Isaacs
- Infectious Diseases Section, Philadelphia Veterans Affairs Medical Center, Philadelphia, PA 19104, USA.,Department of Medicine, Division of Infectious Diseases, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA
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23
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24
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Kotwal GJ. Influence of glycosylation and oligomerization of vaccinia virus complement control protein on level and pattern of functional activity and immunogenicity. Protein Cell 2011; 1:1084-92. [PMID: 21213103 DOI: 10.1007/s13238-010-0139-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2010] [Accepted: 11/23/2010] [Indexed: 11/25/2022] Open
Abstract
Vaccinia virus complement control protein (VCP) is one of the proteins encoded by vaccinia virus to modulate the host inflammatory response. VCP modulates the inflammatory response and protects viral habitat by inhibiting the classical and the alternative pathways of complement activation. The extended structure of VCP, mobility between its sequential domains, charge distribution and type of residues at the binding regions are factors that have been identified to influence its ability to bind to complement proteins. We report that a Lister strain of vaccinia virus encodes a VCP homolog (Lis VCP) that is functional, glycosylated, has two amino acids less than the well-characterized VCP from vaccinia virus WR strain (WR VCP), and the human smallpox inhibitor of complement enzymes (SPICE) from variola virus. The glycosylated VCP of Lister is immunogenic in contrast to the weak immunogenicity of the nonglycosylated VCP. Lis VCP is the only orthopoxviral VCP homolog found to be glycosylated, and we speculate that glycosylation influences its pattern of complement inhibition. We also correlate dimerization of VCP observed only in mammalian and baculovirus expression systems to higher levels of activity than monomers, observed in the yeast expression system.
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Affiliation(s)
- Girish J Kotwal
- Department of Pharmaceutical Sciences, Sullivan University College of Pharmacy, Louisville, KY, USA.
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25
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The Vaccinia virus complement control protein modulates adaptive immune responses during infection. J Virol 2010; 85:2547-56. [PMID: 21191012 DOI: 10.1128/jvi.01474-10] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Complement activation is an important component of the innate immune response against viral infection and also shapes adaptive immune responses. Despite compelling evidence that complement activation enhances T cell and antibody (Ab) responses during viral infection, it is unknown whether inhibition of complement by pathogens alters these responses. Vaccinia virus (VACV) modulates complement activation by encoding a complement regulatory protein called the vaccinia virus complement control protein (VCP). Although VCP has been described as a virulence factor, the mechanisms by which VCP enhances VACV pathogenesis have not been fully defined. Since complement is necessary for optimal adaptive immune responses to several viruses, we hypothesized that VCP contributes to pathogenesis by modulating anti-VACV T cell and Ab responses. In this study, we used an intradermal model of VACV infection to compare pathogenesis of wild-type virus (vv-VCPwt) and a virus lacking VCP (vv-VCPko). vv-VCPko formed smaller lesions in wild-type mice but not in complement-deficient mice. Attenuation of vv-VCPko correlated with increased accumulation of T cells at the site of infection, enhanced neutralizing antibody responses, and reduced viral titers. Importantly, depleting CD8(+) T cells together with CD4(+) T cells, which also eliminated T helper cell-dependent Ab responses, restored vv-VCPko to wild-type levels of virulence. These results suggest that VCP contributes to virulence by dampening both antibody and T cell responses. This work provides insight into how modulation of complement by poxviruses contributes to virulence and demonstrates that a pathogen-encoded complement regulatory protein can modulate adaptive immunity.
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26
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Moulton EA, Bertram P, Chen N, Buller RML, Atkinson JP. Ectromelia virus inhibitor of complement enzymes protects intracellular mature virus and infected cells from mouse complement. J Virol 2010; 84:9128-39. [PMID: 20610727 PMCID: PMC2937632 DOI: 10.1128/jvi.02677-09] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2009] [Accepted: 06/27/2010] [Indexed: 11/20/2022] Open
Abstract
Poxviruses produce complement regulatory proteins to subvert the host's immune response. Similar to the human pathogen variola virus, ectromelia virus has a limited host range and provides a mouse model where the virus and the host's immune response have coevolved. We previously demonstrated that multiple components (C3, C4, and factor B) of the classical and alternative pathways are required to survive ectromelia virus infection. Complement's role in the innate and adaptive immune responses likely drove the evolution of a virus-encoded virulence factor that regulates complement activation. In this study, we characterized the ectromelia virus inhibitor of complement enzymes (EMICE). Recombinant EMICE regulated complement activation on the surface of CHO cells, and it protected complement-sensitive intracellular mature virions (IMV) from neutralization in vitro. It accomplished this by serving as a cofactor for the inactivation of C3b and C4b and by dissociating the catalytic domain of the classical pathway C3 convertase. Infected murine cells initiated synthesis of EMICE within 4 to 6 h postinoculation. The levels were sufficient in the supernatant to protect the IMV, upon release, from complement-mediated neutralization. EMICE on the surface of infected murine cells also reduced complement activation by the alternative pathway. In contrast, classical pathway activation by high-titer antibody overwhelmed EMICE's regulatory capacity. These results suggest that EMICE's role is early during infection when it counteracts the innate immune response. In summary, ectromelia virus produced EMICE within a few hours of an infection, and EMICE in turn decreased complement activation on IMV and infected cells.
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Affiliation(s)
- Elizabeth A. Moulton
- Division of Rheumatology, Department of Medicine, Washington University School of Medicine, Saint Louis, Missouri 63110, Department of Molecular Microbiology and Immunology, Saint Louis University Health Sciences Center, Saint Louis, Missouri 63104
| | - Paula Bertram
- Division of Rheumatology, Department of Medicine, Washington University School of Medicine, Saint Louis, Missouri 63110, Department of Molecular Microbiology and Immunology, Saint Louis University Health Sciences Center, Saint Louis, Missouri 63104
| | - Nanhai Chen
- Division of Rheumatology, Department of Medicine, Washington University School of Medicine, Saint Louis, Missouri 63110, Department of Molecular Microbiology and Immunology, Saint Louis University Health Sciences Center, Saint Louis, Missouri 63104
| | - R. Mark L. Buller
- Division of Rheumatology, Department of Medicine, Washington University School of Medicine, Saint Louis, Missouri 63110, Department of Molecular Microbiology and Immunology, Saint Louis University Health Sciences Center, Saint Louis, Missouri 63104
| | - John P. Atkinson
- Division of Rheumatology, Department of Medicine, Washington University School of Medicine, Saint Louis, Missouri 63110, Department of Molecular Microbiology and Immunology, Saint Louis University Health Sciences Center, Saint Louis, Missouri 63104
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27
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Poxvirus complement control proteins are expressed on the cell surface through an intermolecular disulfide bridge with the viral A56 protein. J Virol 2010; 84:11245-54. [PMID: 20719953 DOI: 10.1128/jvi.00372-10] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The vaccinia virus (VACV) complement control protein (VCP) is an immunomodulatory protein that is both secreted from and expressed on the surface of infected cells. Surface expression of VCP occurs though an interaction with the viral transmembrane protein A56 and is dependent on a free N-terminal cysteine of VCP. Although A56 and VCP have been shown to interact in infected cells, the mechanism remains unclear. To investigate if A56 is sufficient for surface expression, we transiently expressed VCP and A56 in eukaryotic cell lines and found that they interact on the cell surface in the absence of other viral proteins. Since A56 contains three extracellular cysteines, we hypothesized that one of the cysteines may be unpaired and could therefore form a disulfide bridge with VCP. To test this, we generated a series of A56 mutants in which each cysteine was mutated to a serine, and we found that mutation of cysteine 162 abrogated VCP cell surface expression. We also tested the ability of other poxvirus complement control proteins to bind to VACV A56. While the smallpox homolog of VCP is able to bind VACV A56, the ectromelia virus (ECTV) VCP homolog is only able to bind the ECTV homolog of A56, indicating that these proteins may have coevolved. Surface expression of poxvirus complement control proteins may have important implications in viral pathogenesis, as a virus that does not express cell surface VCP is attenuated in vivo. This suggests that surface expression of VCP may contribute to poxvirus pathogenesis.
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28
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Modulation of the host immune response by cowpox virus. Microbes Infect 2010; 12:900-9. [PMID: 20673807 PMCID: PMC3500136 DOI: 10.1016/j.micinf.2010.07.007] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2010] [Revised: 07/09/2010] [Accepted: 07/12/2010] [Indexed: 11/20/2022]
Abstract
Cowpox virus, a zoonotic poxvirus endemic to Eurasia, infects a large number of host species which makes its eradication impossible. The elimination of world-wide smallpox vaccination programs renders the human population increasingly susceptible to infection by orthopoxviruses resulting in a growing number of zoonotic infections including CPXV transmitted from domestic animals to humans. The ability of CPXV to infect a wide range of mammalian host is likely due to the fact that, among the orthopoxviruses, CPXV encodes the most complete set of open reading frames expected to encode immunomodulatory proteins. This renders CPXV particularly interesting for studying poxviral strategies to evade and counteract the host immune responses.
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29
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Lipscomb MF, Hutt J, Lovchik J, Wu T, Lyons CR. The pathogenesis of acute pulmonary viral and bacterial infections: investigations in animal models. ANNUAL REVIEW OF PATHOLOGY-MECHANISMS OF DISEASE 2010; 5:223-52. [PMID: 19824827 DOI: 10.1146/annurev-pathol-121808-102153] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Acute viral and bacterial infections in the lower respiratory tract are major causes of morbidity and mortality worldwide. The proper study of pulmonary infections requires interdisciplinary collaboration among physicians and biomedical scientists to develop rational hypotheses based on clinical studies and to test these hypotheses in relevant animal models. Animal models for common lung infections are essential to understand pathogenic mechanisms and to clarify general mechanisms for host protection in pulmonary infections, as well as to develop vaccines and therapeutics. Animal models for uncommon pulmonary infections, such as those that can be caused by category A biothreat agents, are also very important because the infrequency of these infections in humans limits in-depth clinical studies. This review summarizes our understanding of innate and adaptive immune mechanisms in the lower respiratory tract and discusses how animal models for selected pulmonary pathogens can contribute to our understanding of the pathogenesis of lung infections and to the search for new vaccines and therapies.
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Affiliation(s)
- Mary F Lipscomb
- Departments of Pathology and University of New Mexico School of Medicine, Albuquerque, New Mexico 87131.
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30
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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.
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Affiliation(s)
- Panisadee Avirutnan
- Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, United States
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31
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Surviving mousepox infection requires the complement system. PLoS Pathog 2008; 4:e1000249. [PMID: 19112490 PMCID: PMC2597719 DOI: 10.1371/journal.ppat.1000249] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2008] [Accepted: 11/26/2008] [Indexed: 11/19/2022] Open
Abstract
Poxviruses subvert the host immune response by producing immunomodulatory proteins, including a complement regulatory protein. Ectromelia virus provides a mouse model for smallpox where the virus and the host's immune response have co-evolved. Using this model, our study investigated the role of the complement system during a poxvirus infection. By multiple inoculation routes, ectromelia virus caused increased mortality by 7 to 10 days post-infection in C57BL/6 mice that lack C3, the central component of the complement cascade. In C3−/− mice, ectromelia virus disseminated earlier to target organs and generated higher peak titers compared to the congenic controls. Also, increased hepatic inflammation and necrosis correlated with these higher tissue titers and likely contributed to the morbidity in the C3−/− mice. In vitro, the complement system in naïve C57BL/6 mouse sera neutralized ectromelia virus, primarily through the recognition of the virion by natural antibody and activation of the classical and alternative pathways. Sera deficient in classical or alternative pathway components or antibody had reduced ability to neutralize viral particles, which likely contributed to increased viral dissemination and disease severity in vivo. The increased mortality of C4−/− or Factor B−/− mice also indicates that these two pathways of complement activation are required for survival. In summary, the complement system acts in the first few minutes, hours, and days to control this poxviral infection until the adaptive immune response can react, and loss of this system results in lethal infection. As one of the most successful pathogens ever, smallpox caused death and disfigurement worldwide until its eradication in the 1970s. The complement system, an essential part of the innate immune response, protects against many pathogens; however, its role during smallpox infection is unclear. In this study, we investigated the importance of the complement system in mousepox infection as a model for human smallpox disease. We compared mice with and without genetic deficiencies in complement following infection by multiple routes with ectromelia virus, the causative agent of mousepox. Deficiencies in several complement proteins reduced survival of ectromelia infection. Sera from these same complement-deficient mice also have reduced ability to neutralize ectromelia virus in vitro. In complement-deficient mice, ectromelia virus disseminated from the inoculation site earlier and produced higher levels of virus in the bloodstream, spleen, and liver. The increased infection in the liver resulted in greater tissue damage. We hypothesize that the complement-deficient mice's reduced ability to neutralize ectromelia virus at the inoculation site resulted in earlier dissemination and more severe disease. We have demonstrated that surviving ectromelia virus infection requires the complement system, which suggests that this system may also protect against smallpox infection.
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32
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Nepomnyashchikh TS, Shchelkunov SN. Poxviral immunomodulating proteins: New tools for immunity correction. Mol Biol 2008. [DOI: 10.1134/s0026893308050178] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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33
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Lambris JD, Ricklin D, Geisbrecht BV. Complement evasion by human pathogens. Nat Rev Microbiol 2008; 6:132-42. [PMID: 18197169 DOI: 10.1038/nrmicro1824] [Citation(s) in RCA: 542] [Impact Index Per Article: 33.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The human immune system has developed an elaborate network of cascades for dealing with microbial intruders. Owing to its ability to rapidly recognize and eliminate microorganisms, the complement system is an essential and efficient component of this machinery. However, many pathogenic organisms have found ways to escape the attack of complement through a range of different mechanisms. Recent discoveries in this field have provided important insights into these processes on a molecular level. These vital developments could augment our knowledge of the pathology and treatment of infectious and inflammatory diseases.
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Affiliation(s)
- John D Lambris
- Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine, 422 Curie Boulevard, Philadelphia, Pennsylvania 19104, USA.
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Eisenlohr LC, Rothstein JL. Oncogenic inflammation and autoimmune disease. Autoimmun Rev 2006; 6:107-14. [PMID: 17138254 DOI: 10.1016/j.autrev.2006.04.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2006] [Accepted: 04/14/2006] [Indexed: 01/12/2023]
Abstract
Many models exist to explain the induction and perpetuation of autoimmune diseases. Despite their validation in a variety of animal models, the basis for autoimmune disease in humans remains unknown. Here, we propose that an important aspect of autoimmune disease is the active participation of the target organ due to endogenously produced co-stimulatory factors that cause prolonged antigen presentation and lymphocyte activation. Evidence suggests that a major source of such endogenous signaling comes from newly transformed cells within the target organ that produce pro-inflammatory factors.
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Affiliation(s)
- Laurence C Eisenlohr
- Departments of Microbiology/Immunology and Otolaryngology-HNS, Kimmel Cancer Center, Thomas Jefferson University, 233 South 10th Street, Philadelphia, PA 19107, USA
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35
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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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36
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Likos AM, Sammons SA, Olson VA, Frace AM, Li Y, Olsen-Rasmussen M, Davidson W, Galloway R, Khristova ML, Reynolds MG, Zhao H, Carroll DS, Curns A, Formenty P, Esposito JJ, Regnery RL, Damon IK. A tale of two clades: monkeypox viruses. J Gen Virol 2005; 86:2661-2672. [PMID: 16186219 DOI: 10.1099/vir.0.81215-0] [Citation(s) in RCA: 429] [Impact Index Per Article: 22.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Human monkeypox was first recognized outside Africa in 2003 during an outbreak in the USA that was traced to imported monkeypox virus (MPXV)-infected West African rodents. Unlike the smallpox-like disease described in the Democratic Republic of the Congo (DRC; a Congo Basin country), disease in the USA appeared milder. Here, analyses compared clinical, laboratory and epidemiological features of confirmed human monkeypox case-patients, using data from outbreaks in the USA and the Congo Basin, and the results suggested that human disease pathogenicity was associated with the viral strain. Genomic sequencing of USA, Western and Central African MPXV isolates confirmed the existence of two MPXV clades. A comparison of open reading frames between MPXV clades permitted prediction of viral proteins that could cause the observed differences in human pathogenicity between these two clades. Understanding the molecular pathogenesis and clinical and epidemiological properties of MPXV can improve monkeypox prevention and control.
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Affiliation(s)
- Anna M Likos
- National Center for Infectious Disease, Centers for Disease Control and Prevention, 1600 Clifton Road NE, Mailstop G43, Atlanta, GA 30333, USA
| | - Scott A Sammons
- National Center for Infectious Disease, Centers for Disease Control and Prevention, 1600 Clifton Road NE, Mailstop G43, Atlanta, GA 30333, USA
| | - Victoria A Olson
- National Center for Infectious Disease, Centers for Disease Control and Prevention, 1600 Clifton Road NE, Mailstop G43, Atlanta, GA 30333, USA
| | - A Michael Frace
- National Center for Infectious Disease, Centers for Disease Control and Prevention, 1600 Clifton Road NE, Mailstop G43, Atlanta, GA 30333, USA
| | - Yu Li
- National Center for Infectious Disease, Centers for Disease Control and Prevention, 1600 Clifton Road NE, Mailstop G43, Atlanta, GA 30333, USA
| | - Melissa Olsen-Rasmussen
- National Center for Infectious Disease, Centers for Disease Control and Prevention, 1600 Clifton Road NE, Mailstop G43, Atlanta, GA 30333, USA
| | - Whitni Davidson
- National Center for Infectious Disease, Centers for Disease Control and Prevention, 1600 Clifton Road NE, Mailstop G43, Atlanta, GA 30333, USA
| | - Renee Galloway
- National Center for Infectious Disease, Centers for Disease Control and Prevention, 1600 Clifton Road NE, Mailstop G43, Atlanta, GA 30333, USA
| | - Marina L Khristova
- National Center for Infectious Disease, Centers for Disease Control and Prevention, 1600 Clifton Road NE, Mailstop G43, Atlanta, GA 30333, USA
| | - Mary G Reynolds
- National Center for Infectious Disease, Centers for Disease Control and Prevention, 1600 Clifton Road NE, Mailstop G43, Atlanta, GA 30333, USA
| | - Hui Zhao
- National Center for Infectious Disease, Centers for Disease Control and Prevention, 1600 Clifton Road NE, Mailstop G43, Atlanta, GA 30333, USA
| | - Darin S Carroll
- National Center for Infectious Disease, Centers for Disease Control and Prevention, 1600 Clifton Road NE, Mailstop G43, Atlanta, GA 30333, USA
| | - Aaron Curns
- National Center for Infectious Disease, Centers for Disease Control and Prevention, 1600 Clifton Road NE, Mailstop G43, Atlanta, GA 30333, USA
| | | | - Joseph J Esposito
- National Center for Infectious Disease, Centers for Disease Control and Prevention, 1600 Clifton Road NE, Mailstop G43, Atlanta, GA 30333, USA
| | - Russell L Regnery
- National Center for Infectious Disease, Centers for Disease Control and Prevention, 1600 Clifton Road NE, Mailstop G43, Atlanta, GA 30333, USA
| | - Inger K Damon
- National Center for Infectious Disease, Centers for Disease Control and Prevention, 1600 Clifton Road NE, Mailstop G43, Atlanta, GA 30333, USA
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37
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Chen N, Li G, Liszewski MK, Atkinson JP, Jahrling PB, Feng Z, Schriewer J, Buck C, Wang C, Lefkowitz EJ, Esposito JJ, Harms T, Damon IK, Roper RL, Upton C, Buller RML. Virulence differences between monkeypox virus isolates from West Africa and the Congo basin. Virology 2005; 340:46-63. [PMID: 16023693 PMCID: PMC9534023 DOI: 10.1016/j.virol.2005.05.030] [Citation(s) in RCA: 278] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2005] [Revised: 04/23/2005] [Accepted: 05/25/2005] [Indexed: 11/28/2022]
Abstract
Studies indicate that West African and Congo basin isolates of monkeypox virus (MPXV) are genetically distinct. Here, we show Congo basin MPXV-ZAI-V79 is more virulent for cynomolgus monkeys as compared to presumed West African MPXV-COP-58. This finding may explain the lack of case-fatalities in the U.S. 2003 monkeypox outbreak, which was caused by a West African virus. Virulence differences between West African and Congo basin MPXV are further supported by epidemiological analyses that observed a similar prevalence of antibodies in non-vaccinated humans in both regions, while >90% of reported cases occurred in the Congo basin, and no fatal cases were observed outside of this region. To determine the basis for this difference in virulence, we sequenced the genomes of one human West African isolate, and two presumed West African isolates and compared the sequences to Congo basin MPXV-ZAI-96-I-16. The analysis identified D10L, D14L, B10R, B14R, and B19R as possible virulence genes, with D14L (ortholog of vaccinia complement protein) as a leading candidate.
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Affiliation(s)
- Nanhai Chen
- Department of Molecular Microbiology and Immunology, Saint Louis University Health Sciences Center, M432, St. Louis, MO 63104, USA
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38
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Uvarova EA, Totmenin AV, Sandakhchiev LS, Shchelkunov SN. The gene of the complement-binding protein, an important anti-inflammatory factor of orthopoxviruses, is deleted from the genome of Western African strains of monkeypox virus. DOKL BIOCHEM BIOPHYS 2005; 400:14-6. [PMID: 15846974 DOI: 10.1007/s10628-005-0021-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Affiliation(s)
- E A Uvarova
- Vector Scientific and Research Center of Virology and Biotechnology, Kol'tsovo, Novosibirsk oblast, 630559 Russia
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39
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Johnston JB, McFadden G. Technical knockout: understanding poxvirus pathogenesis by selectively deleting viral immunomodulatory genes. Cell Microbiol 2004; 6:695-705. [PMID: 15236637 DOI: 10.1111/j.1462-5822.2004.00423.x] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The study of viral pathogens with genomes as large and complex as poxviruses represents a constant experimental challenge. Advances in recombinant DNA technologies have provided sophisticated methods to produce mutants defective in one or more viral genes, termed knockout (KO) viruses, thereby facilitating research into the impact of specific gene products on viral pathogenesis. Such strategies have rapidly advanced the systematic mining of many poxvirus genomes and enabled researchers to identify and characterize poxvirus genes whose functions represent the culmination of host and pathogen coevolution. Of particular interest are the multiple classes of virus-encoded immunomodulatory proteins that have evolved specifically to allow poxviruses to evade, obstruct or subvert critical elements within the host innate and acquired immune responses. Functional characterization of these viral genes by generating KO viruses and investigating the phenotypic changes that result is an important tool for understanding the molecular mechanisms underlying poxvirus replication and pathogenesis. Moreover, the insights gained have led to new developments in basic and clinical virology, provided a basis for the design of new vaccines and antivirals, and increased the potential application of poxviruses as investigative tools and sources of biotherapeutics for the treatment of human diseases.
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Affiliation(s)
- J B Johnston
- Biotherapeutics Research Group, Robarts Research Institute and Department of Microbiology and Immunology, University of Western Ontario, London, Canada
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40
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Quenelle DC, Collins DJ, Kern ER. Efficacy of multiple- or single-dose cidofovir against vaccinia and cowpox virus infections in mice. Antimicrob Agents Chemother 2004; 47:3275-80. [PMID: 14506041 PMCID: PMC201130 DOI: 10.1128/aac.47.10.3275-3280.2003] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Orthopoxviruses, including variola and monkeypox, pose risks to human health through natural transmission or potential bioterrorist activities. Since vaccination has not recently been utilized for control of these infections, there is renewed effort in the development of antiviral agents not only for postexposure smallpox therapy but also for treatment of adverse reactions following vaccination. The objectives of this study were to expand on the results of others that cidofovir (CDV) is effective in mice inoculated with cowpox virus (CV) or vaccinia virus (VV) and to document the efficacy of single and interval dosing beginning prior to or after infection, particularly including evaluations using suboptimal doses of CDV. We utilized BALB/c or SCID mice inoculated with CV or VV as models for systemic poxvirus infections. BALB/c mice were inoculated intranasally with CV or VV and treated with CDV prior to or after virus inoculation. CDV, at concentrations as low as 0.7 to 6.7 mg/kg of body weight/day for 5 days, conferred significant protection when treatment was initiated as late as 72 to 96 h postinfection. A single-dose pretreatment or posttreatment with CDV at 3 to 100 mg/kg was effective when given as early as 5 days prior to infection or as late as 3 days after infection with either VV or CV. Interval treatments given every third day beginning 72 h postinfection using 6.7 or 2 mg of CDV/kg also proved effective against CV infections. When SCID mice were inoculated intraperitoneally with CV or VV and treated for 7 to 30 days with CDV, all the mice eventually died during or after cessation of treatment; however, significant delays in time to death and reduction of virus replication in organs occurred in most treated groups, and no resistance to CDV was detected.
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Affiliation(s)
- Debra C Quenelle
- The University of Alabama School of Medicine, Birmingham, Alabama 35233, USA
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41
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Dabo SM, Confer AW, Quijano-Blas RA. Molecular and immunological characterization of Pasteurella multocida serotype A:3 OmpA: evidence of its role in P. multocida interaction with extracellular matrix molecules. Microb Pathog 2003; 35:147-57. [PMID: 12946327 DOI: 10.1016/s0882-4010(03)00098-6] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Pasteurella multocida OmpA-like gene (PmOmpA) was cloned and characterized. The mature protein had a molecular mass of 35,075 Da and significant similarity with Escherichia coli (E. coli) OmpA proteins. Membrane topology analyses predict that like E. coli OmpA, the N-terminal half of PmOmpA exists as an eight-stranded transmembrane antiparallel beta-barrel that displays four variable hydrophilic and surface-exposed regions with predicted antigenic peaks that may be involved in serum resistance or adherence. In addition, the Ala-Pro repeat region between the N-terminal beta-barrel and C-terminal periplasmic domains is completely missing in PmOmpA. PmOmpA was expressed in E. coli and immunoblots analysis revealed that the recombinant PmOmpA was immunogenic, and expressed in vivo. The binding of PmOmpA to biotinylated Madin Darby bovine kidney (MDBK) cells surface proteins, fibronectin and heparin was demonstrated. Furthermore, PmOmpA binds MDBK monolayers and pre-treatment of P. multocida whole cells with anti-PmOmpA significantly reduced adherence to fibronectin. Ligand blot analysis revealed that fibronectin binds to the native and heat modified forms of PmOmpA when heated at 37 and 100 degrees C, respectively. Collectively these data indicate that PmOmpA may be involved in P. multocida 232 adherence to host cells via heparin and/or fibronectin bridging.
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Affiliation(s)
- S M Dabo
- Department of Veterinary Pathobiology, Oklahoma State University, Stillwater, OK 74078-2007, USA.
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42
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Hassett DE. Smallpox infections during pregnancy, lessons on pathogenesis from nonpregnant animal models of infection. J Reprod Immunol 2003; 60:13-24. [PMID: 14568674 DOI: 10.1016/s0165-0378(03)00038-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: 11/21/2022]
Abstract
Both vaccinated and unvaccinated women during pregnancy who contract variola virus, the causative agent of smallpox, suffer much higher mortality rates than nonpregnants. Furthermore, acute maternal smallpox leads to spontaneous abortion, premature termination of pregnancy and early postnatal infant mortality. The mechanisms governing the abortifacient activity of smallpox, as well as the enhanced susceptibility of gestating women to lethal disease, have remained largely unexamined. Experimental poxvirus infections in nonpregnant small animal models have revealed that T helper type 1 (TH1) cytokines promote efficient resolution of these infections whereas type 2 (TH2) cytokines enhance viral pathogenesis. These data, combined with recent understanding of how the immune system is modulated by pregnancy, may offer important clues as to the increased pathogenesis of variola in pregnant women. The aim of this review is to bring together the current literature on the effects of poxvirus infections in nonpregnant hosts, as well as the effects of pregnancy on the immune system, in order to develop unifying concepts that may provide insight into the pathogenesis of variola during pregnancy and why prior vaccination with vaccinia virus the live anti-variola vaccine offers less protection to pregnant women and their unborn children.
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Affiliation(s)
- Daniel E Hassett
- The Scripps Research Institute CVN-9, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA.
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43
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Mullick J, Kadam A, Sahu A. Herpes and pox viral complement control proteins: 'the mask of self'. Trends Immunol 2003; 24:500-7. [PMID: 12967674 DOI: 10.1016/s1471-4906(03)00207-2] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Jayati Mullick
- National Centre for Cell Science, Pune University Campus, Ganeshkhind, Pune 411007, India
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44
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Abstract
Variola virus, the causative agent of smallpox, encodes approximately 200 proteins. Over 80 of these proteins are located in the terminal regions of the genome, where proteins associated with host immune evasion are encoded. To date, only two variola proteins have been characterized. Both are located in the terminal regions and demonstrate immunoregulatory functions. One protein, the smallpox inhibitor of complement enzymes (SPICE), is homologous to a vaccinia virus virulence factor, the vaccinia virus complement-control protein (VCP), which has been found experimentally to be expressed early in the course of vaccinia infection. Both SPICE and VCP are similar in structure and function to the family of mammalian complement regulatory proteins, which function to prevent inadvertent injury to adjacent cells and tissues during complement activation. The second variola protein is the variola virus high-affinity secreted chemokine-binding protein type II (CKBP-II, CBP-II, vCCI), which binds CC-chemokine receptors. The vaccinia homologue of CKBP-II is secreted both early and late in infection. CKBP-II proteins are highly conserved among orthopoxviruses, sharing approximately 85% homology, but are absent in eukaryotes. This characteristic sets it apart from other known virulence factors in orthopoxviruses, which share sequence homology with known mammalian immune regulatory gene products. Future studies of additional variola proteins may help illuminate factors associated with its virulence, pathogenesis and strict human tropism. In addition, these studies may also assist in the development of targeted therapies for the treatment of both smallpox and human immune-related diseases.
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Affiliation(s)
- Lance R Dunlop
- Department of Pathology and Laboratory Medicine, University of Pennsylvania, 220 John Morgan Building, 3620 Hamilton Walk, Philadelphia, PA 19104, USA
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45
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Seet BT, Johnston JB, Brunetti CR, Barrett JW, Everett H, Cameron C, Sypula J, Nazarian SH, Lucas A, McFadden G. Poxviruses and immune evasion. Annu Rev Immunol 2003; 21:377-423. [PMID: 12543935 DOI: 10.1146/annurev.immunol.21.120601.141049] [Citation(s) in RCA: 475] [Impact Index Per Article: 22.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Large DNA viruses defend against hostile assault executed by the host immune system by producing an array of gene products that systematically sabotage key components of the inflammatory response. Poxviruses target many of the primary mediators of innate immunity including interferons, tumor necrosis factors, interleukins, complement, and chemokines. Poxviruses also manipulate a variety of intracellular signal transduction pathways such as the apoptotic response. Many of the poxvirus genes that disrupt these pathways have been hijacked directly from the host immune system, while others have demonstrated no clear resemblance to any known host genes. Nonetheless, the immunological targets and the diversity of strategies used by poxviruses to disrupt these host pathways have provided important insights into diverse aspects of immunology, virology, and inflammation. Furthermore, because of their anti-inflammatory nature, many of these poxvirus proteins hold promise as potential therapeutic agents for acute or chronic inflammatory conditions.
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Affiliation(s)
- Bruce T Seet
- Department of Microbiology and Immunology, University of Western Ontario, London, Canada.
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46
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Smith SA, Sreenivasan R, Krishnasamy G, Judge KW, Murthy KH, Arjunwadkar SJ, Pugh DR, Kotwal GJ. Mapping of regions within the vaccinia virus complement control protein involved in dose-dependent binding to key complement components and heparin using surface plasmon resonance. BIOCHIMICA ET BIOPHYSICA ACTA 2003; 1650:30-9. [PMID: 12922167 DOI: 10.1016/s1570-9639(03)00189-4] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The vaccinia virus complement control protein (VCP) is involved in modulating the host inflammatory response by blocking both pathways of complement activity through its ability to bind C3b and C4b. Other activities arise from VCP's ability to strongly bind heparin. To map regions within VCP involved in binding complement and heparin experimentally, surface plasmon resonance (SPR) and recombinantly expressed VCP (rVCP) constructs were employed. Using C3b or heparin as the immobilized ligand, various rVCP constructs were tested for their ability to bind. Results suggest that VCP is the smallest functional unit able to bind C3b, thereby blocking complement activity, and only a single site, the large basic region near the C-terminus, is involved in heparin binding. Kinetic analysis was also performed to determine the relative binding affinities between rVCP and complement (C3-MA and C4b), as well as rVCP and heparin. rVCP was found to possess a significantly greater affinity for C3-MA than C4b, as indicated by the 1.50e3-fold greater association rate constant (k(a)). This study provides insights for the design of new therapeutic proteins capable of blocking complement activation.
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Affiliation(s)
- Scott A Smith
- Division of Medical Virology, University of Cape Town Medical School, Anzio Road, Observatory, Cape Town, South Africa
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47
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Affiliation(s)
- J B Johnston
- Robarts Research Institute and Department of Microbiology and Immunology, The University of Western Ontario, London, Canada N6G 2V4
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48
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Spiller OB, Blackbourn DJ, Mark L, Proctor DG, Blom AM. Functional activity of the complement regulator encoded by Kaposi's sarcoma-associated herpesvirus. J Biol Chem 2003; 278:9283-9. [PMID: 12645526 DOI: 10.1074/jbc.m211579200] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Kaposi's sarcoma-associated herpesvirus (KSHV) is closely associated with Kaposi's sarcoma and certain B-cell lymphomas. The fourth open reading frame of the KSHV genome encodes a protein (KSHV complement control protein (KCP, previously termed ORF4)) predicted to have complement-regulating activity. Here, we show that soluble KCP strongly enhanced the decay of classical C3-convertase but not the alternative pathway C3-convertase, when compared with the host complement regulators: factor H, C4b-binding protein, and decay-accelerating factor. The equilibrium affinity constant (KD) of KCP for C3b and C4b was determined by surface plasmon resonance analysis to range between 0.47-10 microM and 0.025-6.1 microM, respectively, depending on NaCl concentration and cation presence. Soluble and cell-associated KCP acted as a cofactor for factor I (FI)-mediated cleavage of both C4b and C3b and induced the cleavage products C4d and iC3b, respectively. In the presence of KCP, FI further cleaved iC3b to C3d, which has never been described before as complement receptor 1 only mediates the production of C3dg by FI. KCP would enhance virus pathogenesis through evading complement attack, opsonization, and anaphylaxis but may also aid in targeting KSHV to one of its host reservoirs since C3d is a ligand for complement receptor 2 on B-cells.
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Affiliation(s)
- O Brad Spiller
- University of Wales College of Medicine, Virus Receptor and Immune Evasion Group, Department of Medical Biochemistry, Heath Park, Cardiff CF14 4XX, United Kingdom
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49
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Abstract
Viruses have evolved elegant mechanisms to evade detection and destruction by the host immune system. One of the evasion strategies that have been adopted by large DNA viruses is to encode homologues of cytokines, chemokines and their receptors--molecules that have a crucial role in control of the immune response. Viruses have captured host genes or evolved genes to target specific immune pathways, and so viral genomes can be regarded as repositories of important information about immune processes, offering us a viral view of the host immune system. The study of viral immunomodulatory proteins might help us to uncover new human genes that control immunity, and their characterization will increase our understanding of not only viral pathogenesis, but also normal immune mechanisms. Moreover, viral proteins indicate strategies of immune modulation that might have therapeutic potential.
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Affiliation(s)
- Antonio Alcami
- Department of Medicine and Division of Virology, University of Cambridge, Addenbrooke's Hospital, Level 5, Box 157, Cambridge CB2 2QQ, UK.
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50
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Abstract
The complement system is a potent innate immune mechanism consisting of cascades of proteins which are designed to fight against and annul intrusion of all the foreign pathogens. Although viruses are smaller in size and have relatively simple structure, they are not immune to complement attack. Thus, activation of the complement system can lead to neutralization of cell-free viruses, phagocytosis of C3b-coated viral particles, lysis of virus-infected cells, and generation of inflammatory and specific immune responses. However, to combat host responses and succeed as pathogens, viruses not only have developed/adopted mechanisms to control complement, but also have turned these interactions to their own advantage. Important examples include poxviruses, herpesviruses, retroviruses, paramyxoviruses and picornaviruses. In this review, we provide information on the various complement evasion strategies that viruses have developed to thwart the complement attack of the host. A special emphasis is given on the interactions between the viral proteins that are involved in molecular mimicry and the complement system.
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Affiliation(s)
- John Bernet
- National Centre for Cell Science, Pune University Campus, 411 007 Ganeshkhind, Pune, India
| | - Jayati Mullick
- National Centre for Cell Science, Pune University Campus, 411 007 Ganeshkhind, Pune, India
| | - Akhilesh K. Singh
- National Centre for Cell Science, Pune University Campus, 411 007 Ganeshkhind, Pune, India
| | - Arvind Sahu
- National Centre for Cell Science, Pune University Campus, 411 007 Ganeshkhind, Pune, India
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