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Hutson CL, Kondas AV, Ritter JM, Reed Z, Ostergaard SD, Morgan CN, Gallardo-Romero N, Tansey C, Mauldin MR, Salzer JS, Hughes CM, Goldsmith CS, Carroll D, Olson VA. Teaching a new mouse old tricks: Humanized mice as an infection model for Variola virus. PLoS Pathog 2021; 17:e1009633. [PMID: 34547055 PMCID: PMC8454956 DOI: 10.1371/journal.ppat.1009633] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Accepted: 05/11/2021] [Indexed: 01/12/2023] Open
Abstract
Smallpox, caused by the solely human pathogen Variola virus (VARV), was declared eradicated in 1980. While known VARV stocks are secure, smallpox remains a bioterrorist threat agent. Recent U.S. Food and Drug Administration approval of the first smallpox anti-viral (tecovirimat) therapeutic was a successful step forward in smallpox preparedness; however, orthopoxviruses can become resistant to treatment, suggesting a multi-therapeutic approach is necessary. Animal models are required for testing medical countermeasures (MCMs) and ideally MCMs are tested directly against the pathogen of interest. Since VARV only infects humans, a representative animal model for testing therapeutics directly against VARV remains a challenge. Here we show that three different humanized mice strains are highly susceptible to VARV infection, establishing the first small animal model using VARV. In comparison, the non-humanized, immunosuppressed background mouse was not susceptible to systemic VARV infection. Following an intranasal VARV challenge that mimics the natural route for human smallpox transmission, the virus spread systemically within the humanized mouse before mortality (~ 13 days post infection), similar to the time from exposure to symptom onset for ordinary human smallpox. Our identification of a permissive/representative VARV animal model can facilitate testing of MCMs in a manner consistent with their intended use.
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Affiliation(s)
- Christina L. Hutson
- Poxvirus and Rabies Branch, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Ashley V. Kondas
- Poxvirus and Rabies Branch, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Jana M. Ritter
- Infectious Diseases Pathology Branch, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Zachary Reed
- Poxvirus and Rabies Branch, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Sharon Dietz Ostergaard
- Comparative Medicine Branch, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Clint N. Morgan
- Poxvirus and Rabies Branch, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Nadia Gallardo-Romero
- Poxvirus and Rabies Branch, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Cassandra Tansey
- Comparative Medicine Branch, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Matthew R. Mauldin
- Poxvirus and Rabies Branch, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Johanna S. Salzer
- Poxvirus and Rabies Branch, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Christine M. Hughes
- Poxvirus and Rabies Branch, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Cynthia S. Goldsmith
- Infectious Diseases Pathology Branch, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Darin Carroll
- Poxvirus and Rabies Branch, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Victoria A. Olson
- Poxvirus and Rabies Branch, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
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Sinkovits G, Mező B, Réti M, Müller V, Iványi Z, Gál J, Gopcsa L, Reményi P, Szathmáry B, Lakatos B, Szlávik J, Bobek I, Prohászka ZZ, Förhécz Z, Csuka D, Hurler L, Kajdácsi E, Cervenak L, Kiszel P, Masszi T, Vályi-Nagy I, Prohászka Z. Complement Overactivation and Consumption Predicts In-Hospital Mortality in SARS-CoV-2 Infection. Front Immunol 2021; 12:663187. [PMID: 33841446 PMCID: PMC8027327 DOI: 10.3389/fimmu.2021.663187] [Citation(s) in RCA: 77] [Impact Index Per Article: 25.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Accepted: 03/05/2021] [Indexed: 12/30/2022] Open
Abstract
Objectives Uncontrolled thromboinflammation plays an important role in the pathogenesis of coronavirus disease (COVID-19) caused by SARS-CoV-2 virus. Complement was implicated as key contributor to this process, therefore we hypothesized that markers of the complement profile, indicative for the activation state of the system, may be related to the severity and mortality of COVID-19. Methods In this prospective cohort study samples of 102 hospitalized and 26 outpatients with PCR-confirmed COVID-19 were analyzed. Primary outcome was in-hospital, COVID-19 related mortality, and secondary outcome was COVID-19 severity as assessed by the WHO ordinal scale. Complement activity of alternative and classical pathways, its factors, regulators, and activation products were measured by hemolytic titration, turbidimetry, or enzyme-immunoassays. Clinical covariates and markers of inflammation were extracted from hospital records. Results Increased complement activation was characteristic for hospitalized COVID-19 patients. Complement activation was significantly associated with markers of inflammation, such as interleukin-6, C-reactive protein, and ferritin. Twenty-five patients died during hospital stay due to COVID-19 related illness. Patients with uncontrolled complement activation leading to consumption of C3 and decrease of complement activity were more likely to die, than those who had complement activation without consumption. Cox models identified anaphylatoxin C3a, and C3 overactivation and consumption (ratio of C3a/C3) as predictors of in-hospital mortality [HR of 3.63 (1.55–8.45, 95% CI) and 6.1 (2.1–17.8), respectively]. Conclusion Increased complement activation is associated with advanced disease severity of COVID-19. Patients with SARS-CoV-2 infection are more likely to die when the disease is accompanied by overactivation and consumption of C3. These results may provide observational evidence and further support to studies on complement inhibitory drugs for the treatment of COVID-19.
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Affiliation(s)
- György Sinkovits
- Department of Internal Medicine and Haematology, Semmelweis University, Budapest, Hungary
| | - Blanka Mező
- Department of Internal Medicine and Haematology, Semmelweis University, Budapest, Hungary.,Research Group for Immunology and Haematology, Semmelweis University-Eötvös Loránd Research Network (Office for Supported Research Groups), Budapest, Hungary
| | - Marienn Réti
- Department of Haematology and Stem Cell Transplantation, Central Hospital of Southern Pest National Institute of Haematology and Infectious Diseases, Budapest, Hungary
| | - Veronika Müller
- Department of Pulmonology, Semmelweis University, Budapest, Hungary
| | - Zsolt Iványi
- Department of Anaesthesiology and Intensive Therapy, Semmelweis University, Budapest, Hungary
| | - János Gál
- Department of Anaesthesiology and Intensive Therapy, Semmelweis University, Budapest, Hungary
| | - László Gopcsa
- Department of Haematology and Stem Cell Transplantation, Central Hospital of Southern Pest National Institute of Haematology and Infectious Diseases, Budapest, Hungary
| | - Péter Reményi
- Department of Haematology and Stem Cell Transplantation, Central Hospital of Southern Pest National Institute of Haematology and Infectious Diseases, Budapest, Hungary
| | - Beáta Szathmáry
- Department of Infectology, Central Hospital of Southern Pest National Institute of Haematology and Infectious Diseases, Budapest, Hungary
| | - Botond Lakatos
- Department of Infectology, Central Hospital of Southern Pest National Institute of Haematology and Infectious Diseases, Budapest, Hungary
| | - János Szlávik
- Department of Infectology, Central Hospital of Southern Pest National Institute of Haematology and Infectious Diseases, Budapest, Hungary
| | - Ilona Bobek
- Department of Anaesthesiology and Intensive Therapy, Central Hospital of Southern Pest National Institute of Haematology and Infectious Diseases, Budapest, Hungary
| | - Zita Z Prohászka
- Department of Internal Medicine and Haematology, Semmelweis University, Budapest, Hungary
| | - Zsolt Förhécz
- Department of Internal Medicine and Haematology, Semmelweis University, Budapest, Hungary
| | - Dorottya Csuka
- Department of Internal Medicine and Haematology, Semmelweis University, Budapest, Hungary
| | - Lisa Hurler
- Department of Internal Medicine and Haematology, Semmelweis University, Budapest, Hungary
| | - Erika Kajdácsi
- Department of Internal Medicine and Haematology, Semmelweis University, Budapest, Hungary
| | - László Cervenak
- Department of Internal Medicine and Haematology, Semmelweis University, Budapest, Hungary
| | - Petra Kiszel
- Research Group for Immunology and Haematology, Semmelweis University-Eötvös Loránd Research Network (Office for Supported Research Groups), Budapest, Hungary
| | - Tamás Masszi
- Department of Internal Medicine and Haematology, Semmelweis University, Budapest, Hungary
| | - István Vályi-Nagy
- Department of Infectology, Central Hospital of Southern Pest National Institute of Haematology and Infectious Diseases, Budapest, Hungary.,Department of Anaesthesiology and Intensive Therapy, Central Hospital of Southern Pest National Institute of Haematology and Infectious Diseases, Budapest, Hungary
| | - Zoltán Prohászka
- Department of Internal Medicine and Haematology, Semmelweis University, Budapest, Hungary.,Research Group for Immunology and Haematology, Semmelweis University-Eötvös Loránd Research Network (Office for Supported Research Groups), Budapest, Hungary
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Babkin IV, Babkina IN. The origin of the variola virus. Viruses 2015; 7:1100-12. [PMID: 25763864 PMCID: PMC4379562 DOI: 10.3390/v7031100] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2014] [Revised: 01/14/2015] [Accepted: 02/26/2015] [Indexed: 11/16/2022] Open
Abstract
The question of the origin of smallpox, one of the major menaces to humankind, is a constant concern for the scientific community. Smallpox is caused by the agent referred to as the variola virus (VARV), which belongs to the genus Orthopoxvirus. In the last century, smallpox was declared eradicated from the human community; however, the mechanisms responsible for the emergence of new dangerous pathogens have yet to be unraveled. Evolutionary analyses of the molecular biological genomic data of various orthopoxviruses, involving a wide range of epidemiological and historical information about smallpox, have made it possible to date the emergence of VARV. Comparisons of the VARV genome to the genomes of the most closely related orthopoxviruses and the examination of the distribution their natural hosts' ranges suggest that VARV emerged 3000 to 4000 years ago in the east of the African continent. The VARV evolution rate has been estimated to be approximately 2 × 10-6 substitutions/site/year for the central conserved genomic region and 4 × 10-6 substitutions/site/year for the synonymous substitutions in the genome. Presumably, the introduction of camels to Africa and the concurrent changes to the climate were the particular factors that triggered the divergent evolution of a cowpox-like ancestral virus and thereby led to the emergence of VARV.
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Affiliation(s)
- Igor V Babkin
- Laboratory of Molecular Microbiology, Institute of Chemical Biology and Fundamental Medicine, Novosibirsk 630090, Russia.
| | - Irina N Babkina
- Laboratory of Molecular Microbiology, Institute of Chemical Biology and Fundamental Medicine, Novosibirsk 630090, Russia.
- JSC VECTOR-BEST, Novosibirsk 630559, Russia.
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Interplay between Kaposi's sarcoma-associated herpesvirus and the innate immune system. Cytokine Growth Factor Rev 2014; 25:597-609. [PMID: 25037686 DOI: 10.1016/j.cytogfr.2014.06.001] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2014] [Accepted: 06/16/2014] [Indexed: 02/04/2023]
Abstract
Understanding of the innate immune response to viral infections is rapidly progressing, especially with regards to the detection of DNA viruses. Kaposi's sarcoma-associated herpesvirus (KSHV) is a large dsDNA virus that is responsible for three human diseases: Kaposi's sarcoma, primary effusion lymphoma and multicentric Castleman's disease. The major target cells of KSHV (B cells and endothelial cells) express a wide range of pattern recognition receptors (PRRs) and play a central role in mobilizing inflammatory responses. On the other hand, KSHV encodes an array of immune evasion genes, including several pirated host genes, which interfere with multiple aspects of the immune response. This review summarizes current understanding of innate immune recognition of KSHV and the role of immune evasion genes that shape the antiviral and inflammatory responses.
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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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Lepiller Q, Aziz Khan K, Di Martino V, Herbein G. Cytomegalovirus and tumors: two players for one goal-immune escape. Open Virol J 2011; 5:60-9. [PMID: 21760870 PMCID: PMC3134960 DOI: 10.2174/1874357901105010060] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2011] [Revised: 04/10/2011] [Accepted: 04/12/2011] [Indexed: 12/22/2022] Open
Abstract
Cytomegalovirus (CMV) and the human tumor cell share the same objectives: escape the recognition and destruction by the immune system and establish a state of immune tolerance conducive for their development. For early tumor development, the escape of the first lines of defense of the immune surveillance is a critical step which determines survival or destruction. The presence of CMV on the tumor site and its involvement in carcinogenesis as initiator or promoter is increasingly documented. In this article, we highlight the similarity between mechanisms used by tumors and CMV to circumvent the immune defenses and evade from immune surveillance. We suggest that CMV and tumors help one another for their common objective. CMV gets shelter in immunologically poor environment of the tumor cells. In return CMV, by acting directly on the cancer cell and/or on the tumor microenvironment, provides the tumor cell the ways to promote its immune escape and development of immune tolerance.
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Affiliation(s)
- Quentin Lepiller
- Department of Virology, University of Franche-Comte, UPRES EA 4266, IFR 133, CHU Besancon, F-25030 Besanon, France
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7
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Folly BB, Weffort-Santos AM, Fathman CG, Soares LRB. Dengue-2 structural proteins associate with human proteins to produce a coagulation and innate immune response biased interactome. BMC Infect Dis 2011; 11:34. [PMID: 21281507 PMCID: PMC3037883 DOI: 10.1186/1471-2334-11-34] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2010] [Accepted: 01/31/2011] [Indexed: 11/17/2022] Open
Abstract
Background Dengue virus infection is a public health threat to hundreds of millions of individuals in the tropical regions of the globe. Although Dengue infection usually manifests itself in its mildest, though often debilitating clinical form, dengue fever, life-threatening complications commonly arise in the form of hemorrhagic shock and encephalitis. The etiological basis for the virus-induced pathology in general, and the different clinical manifestations in particular, are not well understood. We reasoned that a detailed knowledge of the global biological processes affected by virus entry into a cell might help shed new light on this long-standing problem. Methods A bacterial two-hybrid screen using DENV2 structural proteins as bait was performed, and the results were used to feed a manually curated, global dengue-human protein interaction network. Gene ontology and pathway enrichment, along with network topology and microarray meta-analysis, were used to generate hypothesis regarding dengue disease biology. Results Combining bioinformatic tools with two-hybrid technology, we screened human cDNA libraries to catalogue proteins physically interacting with the DENV2 virus structural proteins, Env, cap and PrM. We identified 31 interacting human proteins representing distinct biological processes that are closely related to the major clinical diagnostic feature of dengue infection: haemostatic imbalance. In addition, we found dengue-binding human proteins involved with additional key aspects, previously described as fundamental for virus entry into cells and the innate immune response to infection. Construction of a DENV2-human global protein interaction network revealed interesting biological properties suggested by simple network topology analysis. Conclusions Our experimental strategy revealed that dengue structural proteins interact with human protein targets involved in the maintenance of blood coagulation and innate anti-viral response processes, and predicts that the interaction of dengue proteins with a proposed human protein interaction network produces a modified biological outcome that may be behind the hallmark pathologies of dengue infection.
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Affiliation(s)
- Brenda B Folly
- Federal University of Paraná, Pharmaceutical Sciences Post-graduation Program, Av. Pref. Lothário Meissner 632, CEP 80210-170, Curitiba-PR, Brazil
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Zhang Z, Li Y, Xu S, Chen F, Zhang L, Jiang B, Chen X. Fusion to chicken C3d enhances the immunogenicity of the M2 protein of avian influenza virus. Virol J 2010; 7:89. [PMID: 20459691 PMCID: PMC2887435 DOI: 10.1186/1743-422x-7-89] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2010] [Accepted: 05/09/2010] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND Current vaccines to avian influenzae virus (AIV), a highly contagious disease of birds, need to be constantly updated due to the high level of variation in the target antigens. Therefore, a vaccine that could induce broad cross protection against AIV is required. The M2 membrane protein is structurally conserved amongst AIV subtypes but tends in induce a poor immune response, whereas C3d has been shown in many species to enhance immunogenicity. In this study, we investigated the potential of M2-avian C3d fusion proteins to provide effective immunity. RESULTS We fused chicken complement C3d to sM2 (M2 protein with the transmembrane region deleted) of AIV and expressed four fusion proteins, GST (Glutathione S-transferase tagged proteins in pGEX expression vector) -C3d-sM2, GST-C3d-L2-sM2, GST-C3d-L1-C3d-sM2 and GST-C3d-L1-C3d-L2-sM2 were used to immunize mice. In addition, Specific pathogen free (SPF) chickens were inoculated with the plasmids pcDNA-sM2, pcDNA-C3d-L1-C3d-L2-sM2, GST-sM2 and GST-C3d-L1-C3d-L2-sM2. The immune response was monitored by an enzyme-linked immunosorbent assay (ELISA) for sM2 antibody, and all the test animals were challenged with A/chicken/Bei Jing/WD9/98 (H9N2) virus. Results revealed that the anti-sM2 antibody in mice and chickens vaccinated with these proteins was higher than the nonfused forms of sM2, the GST-C3d-L1-C3d-L2-sM2 groups have conferred the highest 30% and 20% protection ratio in mice and chickens respectively. In addition, the pcDNA-C3d-L1-C3d-L2-sM2 also enhances the antibody responses to sM2 compared to pcDNA-sM2 in chickens, and acquired 13.3% protection ratio. CONCLUSION These results indicated that chicken C3d enhanced the humoral immunity against AIV M2 protein either fused proteins expressed by the prokaryotic system or with the DNA vaccine. Nevertheless, in view of the poor protection ratio for these animals, we speculated that this is not a worthy developing of vaccine in these constructs.
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Affiliation(s)
- Zhenhua Zhang
- College of Animal Medicine, China Agricultural University, Beijing 100094, China
- Institute of Animal Husbandry and Veterinary Medicine, Beijing Academy of Agricultural and Forestry Sciences, Beijing 100097, China
| | - Yongqing Li
- Institute of Animal Husbandry and Veterinary Medicine, Beijing Academy of Agricultural and Forestry Sciences, Beijing 100097, China
| | - Shufang Xu
- Institute of Animal Husbandry and Veterinary Medicine, Beijing Academy of Agricultural and Forestry Sciences, Beijing 100097, China
| | - Fuyong Chen
- College of Animal Medicine, China Agricultural University, Beijing 100094, China
| | - Li Zhang
- Institute of Animal Husbandry and Veterinary Medicine, Beijing Academy of Agricultural and Forestry Sciences, Beijing 100097, China
| | - Beiyu Jiang
- Institute of Animal Husbandry and Veterinary Medicine, Beijing Academy of Agricultural and Forestry Sciences, Beijing 100097, China
| | - Xiaoling Chen
- Institute of Animal Husbandry and Veterinary Medicine, Beijing Academy of Agricultural and Forestry Sciences, Beijing 100097, China
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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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Complement is an essential component of the immune response to adeno-associated virus vectors. J Virol 2008; 82:2727-40. [PMID: 18199646 DOI: 10.1128/jvi.01990-07] [Citation(s) in RCA: 103] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Adeno-associated virus (AAV) vectors are associated with relatively mild host immune responses in vivo. Although AAV induces very weak innate immune responses, neutralizing antibodies against the vector capsid and transgene still occur. To understand further the basis of the antiviral immune response to AAV vectors, studies were performed to characterize AAV interactions with macrophages. Primary mouse macrophages and human THP-1 cells transduced in vitro using an AAV serotype 2 (AAV2) vector encoding green fluorescent protein did not result in measurable transgene expression. An assessment of internalized vector genomes showed that AAV2 vector uptake was enhanced in the presence of normal but not heat-inactivated or C3-depleted mouse/human serum. Enhanced uptake in the presence of serum coincided with increased macrophage activation as determined by the expression of NF-kappaB-dependent genes such as macrophage inflammatory protein 2 (MIP-2), interleukin-1beta (IL-1beta), IL-8, and MIP-1beta. AAV vector serotypes 1 and 8 also activated human and mouse macrophages in a serum-dependent manner. Immunoprecipitation studies demonstrated the binding of iC3b complement protein to the AAV2 capsid in human serum. AAV2 did not activate the alternative pathway of the complement cascade and lacked cofactor activity for factor I-mediated degradation of C3b to iC3b. Instead, our results suggest that the AAV capsid also binds complement regulatory protein factor H. In vivo, complement receptor 1/2- and C3-deficient mice displayed impaired humoral immunity against AAV2 vectors, with a delay in antibody development and significantly lower neutralizing antibody titers. These results show that the complement system is an essential component of the host immune response to AAV.
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Zipfel PF, Mihlan M, Skerka C. The alternative pathway of complement: a pattern recognition system. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2007; 598:80-92. [PMID: 17892206 DOI: 10.1007/978-0-387-71767-8_7] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Peter F Zipfel
- Department of Infection Biology, Leibniz Institute for Natural Product Research and Infection Biology, Hans Knöll Institute for Natural Products Research, Jena, Germany.
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12
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Ciulla E, Emery A, Konz D, Krushkal J. Evolutionary history of orthopoxvirus proteins similar to human complement regulators. Gene 2005; 355:40-7. [PMID: 16023794 PMCID: PMC9628764 DOI: 10.1016/j.gene.2005.05.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2004] [Revised: 03/28/2005] [Accepted: 05/10/2005] [Indexed: 11/29/2022]
Abstract
Orthopoxviruses include many important pathogens such as variola major virus, camelpox, buffalopox, monkeypox, cowpox, and variola minor viruses. This group of viruses also includes vaccinia virus, which is extensively used in human vaccine development. Genomes of orthopoxviruses encode proteins with sequences similar to human regulators of complement activation (RCA) that contain tandem short consensus repeats (SCRs). We employed phylogenetic tree analysis to evaluate the structural relationships among SCRs of orthopoxvirus RCA-like proteins and those of human complement regulators. The human complement RCA proteins analyzed were factor H (FH), C4 binding protein alpha chain, membrane cofactor protein (MCP), decay accelerating factor (DAF), and complement receptors type 1 (CR1) and 2 (CR2). Sequences of key poxvirus regulators of complement activation, vaccinia virus complement control protein (VCP), smallpox inhibitor of complement enzymes (SPICE), and cowpox inflammation modulatory protein (IMP) were similar to SCRs 1 through 5 of C4 binding protein, alpha chain, and they were also clustered with other homologous repeats of MCP, DAF, CR1, CR2, and FH. Phylogenetic clustering of RCA sequences suggested that poxvirus complement regulators VCP, SPICE, and IMP arose from a single ancestral sequence that shared similarity with all human regulators of complement activation. Any changes in poxvirus complement regulators leading to the enhancement of their ability to regulate complement activation likely resulted from new mutations in the viral lineages.
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Affiliation(s)
- Emily Ciulla
- Department of Biology and Biotechnology, Worcester Polytechnic Institute, Worcester, MA, USA
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Bernet J, Mullick J, Panse Y, Parab PB, Sahu A. Kinetic analysis of the interactions between vaccinia virus complement control protein and human complement proteins C3b and C4b. J Virol 2004; 78:9446-57. [PMID: 15308738 PMCID: PMC506936 DOI: 10.1128/jvi.78.17.9446-9457.2004] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The vaccinia virus complement control protein (VCP) is an immune evasion protein of vaccinia virus. Previously, VCP has been shown to bind and support inactivation of host complement proteins C3b and C4b and to protect the vaccinia virions from antibody-dependent complement-enhanced neutralization. However, the molecular mechanisms involved in the interaction of VCP with its target proteins C3b and C4b have not yet been elucidated. We have utilized surface plasmon resonance technology to study the interaction of VCP with C3b and C4b. We measured the kinetics of binding of the viral protein to its target proteins and compared it with human complement regulators factor H and sCR1, assessed the influence of immobilization of ligand on the binding kinetics, examined the effect of ionic contacts on these interactions, and sublocalized the binding site on C3b and C4b. Our results indicate that (i) the orientation of the ligand is important for accurate determination of the binding constants, as well as the mechanism of binding; (ii) in contrast to factor H and sCR1, the binding of VCP to C3b and C4b follows a simple 1:1 binding model and does not involve multiple-site interactions as predicted earlier; (iii) VCP has a 4.6-fold higher affinity for C4b than that for C3b, which is also reflected in its factor I cofactor activity; (iv) ionic interactions are important for VCP-C3b and VCP-C4b complex formation; (v) VCP does not bind simultaneously to C3b and C4b; and (vi) the binding site of VCP on C3b and C4b is located in the C3dg and C4c regions, respectively.
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Affiliation(s)
- John Bernet
- National Centre for Cell Science, Pune University Campus, Ganeshkhind, Pune, India
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Affiliation(s)
- Clare E Blue
- Division of Virology, Institute of Biomedical and Life Sciences, University of Glasgow, Glasgow, UK
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