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Vezzani G, Pimazzoni S, Ferranti R, Calò S, Monda G, Amendola D, Frigimelica E, Maione D, Cortese M, Merola M. Human immunoglobulins are transported to HCMV viral envelope by viral Fc gamma receptors-dependent and independent mechanisms. Front Microbiol 2023; 13:1106401. [PMID: 36726564 PMCID: PMC9885202 DOI: 10.3389/fmicb.2022.1106401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Accepted: 12/20/2022] [Indexed: 01/18/2023] Open
Abstract
Human cytomegaloviruses (HCMVs) employ many different mechanisms to escape and subvert the host immune system, including expression of the viral IgG Fcγ receptors (vFcγRs) RL11 (gp34), RL12 (gp95), RL13 (gpRL13), and UL119 (gp68) gene products. The role of vFcγRs in HCMV pathogenesis has been reported to operate in infected cells by interfering with IgG-mediated effector functions. We found that gp34 and gp68 are envelope proteins that bind and internalize human IgGs on the surface of infected cells. Internalized IgGs are then transported on the envelope of viral particles in a vFcR-dependent mechanism. This mechanism is also responsible for the incorporation on the virions of the anti-gH neutralizing antibody MSL-109. Intriguingly, we show that gp68 is responsible for MSL-109 incorporation, but it is dispensable for other anti-HCMV antibodies that do not need this function to be transported on mature virions. HCMV-infected cells grown in presence of anti-HCMV monoclonal antibodies generate a viral progeny still infective and possible to be neutralized. This is the first example of a virus carrying neutralizing IgGs on its surface and their possible role is discussed.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Mirko Cortese
- GSK, Siena, Italy,Department of Environmental Biological and Pharmaceutical Sciences and Technologies, University of Campania “Luigi Vanvitelli”, Caserta, Italy,Mirko Cortese, ✉
| | - Marcello Merola
- GSK, Siena, Italy,Department of Biology, University of Naples Federico II, Naples, Italy,*Correspondence: Marcello Merola, ✉
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Petrini S, Martucciello A, Righi C, Cappelli G, Torresi C, Grassi C, Scoccia E, Costantino G, Casciari C, Sabato R, Giammarioli M, De Carlo E, Feliziani F. Assessment of Different Infectious Bovine Rhinotracheitis Marker Vaccines in Calves. Vaccines (Basel) 2022; 10:vaccines10081204. [PMID: 36016092 PMCID: PMC9412430 DOI: 10.3390/vaccines10081204] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2022] [Revised: 07/25/2022] [Accepted: 07/26/2022] [Indexed: 01/27/2023] Open
Abstract
Three commercially available infectious bovine rhinotracheitis (IBR) live marker vaccines were evaluated for their ability to provide clinical protection to vaccinated calves against wild-type (wt) Bovine alphaherpesvirus-1 (BoHV-1) challenge and their possible effect on wt BoHV-1 latency reactivation following the challenge. On 35 post-vaccination days (PVDs), all animals were challenged with wt BoHV-1. Only the calves in the control group developed severe forms of IBR. The reactivation of latent BoHV-1 was induced by dexamethasone (DMS) treatment on 28 post-challenge days (PCDs). All animals showed IBR clinical signs on three post-DMS treatment days (PDTDs). On PVD 14, all vaccinated animals developed neutralizing antibodies (NAs), whereas in control animals, the NAs appeared post-challenge. The positivity for glycoprotein-B (gB) was detected using real-time polymerase chain reactions in all animals from PCDs 1 to 7. In contrast, the gB-positivity was observed in the immunized calves from PDTDs 3 to 10. Positive expression of gD and gE was observed in nasal swabs of all calves on PDTD 7. These findings suggested that the IBR marker vaccines evaluated in this study protected against wt BoHV-1-induced disease but not against wt BoHV-1-induced latency reactivation, indicating the necessity of developing new products to protect animals from wt BoHV-1-induced latency.
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Affiliation(s)
- Stefano Petrini
- National Reference Centre for Infectious Bovine Rhinotracheitis (IBR), Istituto Zooprofilattico Sperimentale Umbria-Marche, “Togo Rosati,” 06126 Perugia, Italy; (C.R.); (C.T.); (E.S.); (G.C.); (C.C.); (R.S.); (M.G.); (F.F.)
- Correspondence: ; Tel.: +39-075-343-3069
| | - Alessandra Martucciello
- National Reference Centre for Hygiene and Technology of Breeding and Buffalo Production, Istituto Zooprofilattico Sperimentale del Mezzogiorno, 84131 Salerno, Italy; (A.M.); (G.C.); (C.G.); (E.D.C.)
| | - Cecilia Righi
- National Reference Centre for Infectious Bovine Rhinotracheitis (IBR), Istituto Zooprofilattico Sperimentale Umbria-Marche, “Togo Rosati,” 06126 Perugia, Italy; (C.R.); (C.T.); (E.S.); (G.C.); (C.C.); (R.S.); (M.G.); (F.F.)
| | - Giovanna Cappelli
- National Reference Centre for Hygiene and Technology of Breeding and Buffalo Production, Istituto Zooprofilattico Sperimentale del Mezzogiorno, 84131 Salerno, Italy; (A.M.); (G.C.); (C.G.); (E.D.C.)
| | - Claudia Torresi
- National Reference Centre for Infectious Bovine Rhinotracheitis (IBR), Istituto Zooprofilattico Sperimentale Umbria-Marche, “Togo Rosati,” 06126 Perugia, Italy; (C.R.); (C.T.); (E.S.); (G.C.); (C.C.); (R.S.); (M.G.); (F.F.)
| | - Carlo Grassi
- National Reference Centre for Hygiene and Technology of Breeding and Buffalo Production, Istituto Zooprofilattico Sperimentale del Mezzogiorno, 84131 Salerno, Italy; (A.M.); (G.C.); (C.G.); (E.D.C.)
| | - Eleonora Scoccia
- National Reference Centre for Infectious Bovine Rhinotracheitis (IBR), Istituto Zooprofilattico Sperimentale Umbria-Marche, “Togo Rosati,” 06126 Perugia, Italy; (C.R.); (C.T.); (E.S.); (G.C.); (C.C.); (R.S.); (M.G.); (F.F.)
| | - Giulia Costantino
- National Reference Centre for Infectious Bovine Rhinotracheitis (IBR), Istituto Zooprofilattico Sperimentale Umbria-Marche, “Togo Rosati,” 06126 Perugia, Italy; (C.R.); (C.T.); (E.S.); (G.C.); (C.C.); (R.S.); (M.G.); (F.F.)
| | - Cristina Casciari
- National Reference Centre for Infectious Bovine Rhinotracheitis (IBR), Istituto Zooprofilattico Sperimentale Umbria-Marche, “Togo Rosati,” 06126 Perugia, Italy; (C.R.); (C.T.); (E.S.); (G.C.); (C.C.); (R.S.); (M.G.); (F.F.)
| | - Roberto Sabato
- National Reference Centre for Infectious Bovine Rhinotracheitis (IBR), Istituto Zooprofilattico Sperimentale Umbria-Marche, “Togo Rosati,” 06126 Perugia, Italy; (C.R.); (C.T.); (E.S.); (G.C.); (C.C.); (R.S.); (M.G.); (F.F.)
| | - Monica Giammarioli
- National Reference Centre for Infectious Bovine Rhinotracheitis (IBR), Istituto Zooprofilattico Sperimentale Umbria-Marche, “Togo Rosati,” 06126 Perugia, Italy; (C.R.); (C.T.); (E.S.); (G.C.); (C.C.); (R.S.); (M.G.); (F.F.)
| | - Esterina De Carlo
- National Reference Centre for Hygiene and Technology of Breeding and Buffalo Production, Istituto Zooprofilattico Sperimentale del Mezzogiorno, 84131 Salerno, Italy; (A.M.); (G.C.); (C.G.); (E.D.C.)
| | - Francesco Feliziani
- National Reference Centre for Infectious Bovine Rhinotracheitis (IBR), Istituto Zooprofilattico Sperimentale Umbria-Marche, “Togo Rosati,” 06126 Perugia, Italy; (C.R.); (C.T.); (E.S.); (G.C.); (C.C.); (R.S.); (M.G.); (F.F.)
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The Structures and Functions of VZV Glycoproteins. Curr Top Microbiol Immunol 2021; 438:25-58. [PMID: 34731265 DOI: 10.1007/82_2021_243] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
The virions of all enveloped viruses, including those of the Herpesviridae, must bind to the cell surface then undergo a process of membrane fusion between the cell plasma membrane and the virus particle envelope. As for all herpesviruses, glycoproteins in the virion envelope are the modus operandi of these events.
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Evaluation of Recombinant Herpes Zoster Vaccine for Primary Immunization of Varicella-seronegative Transplant Recipients. Transplantation 2021; 105:2316-2323. [PMID: 33528118 DOI: 10.1097/tp.0000000000003621] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
BACKGROUND Immunization of VZV-seronegative solid organ transplant (SOT) patients using the live-attenuated varicella vaccine is generally contraindicated, leaving no widely applicable immunization option. The recombinant subunit herpes zoster vaccine (RZV) is indicated for VZV seropositive persons to prevent shingles but could potentially also protect VZV-seronegative persons against varicella. We performed a safety and immunogenicity evaluation of RZV in VZV-seronegative SOT recipients as an option for protection. METHODS VZV-seronegative adult SOT patients with no history of varicella/shingles vaccine or disease were given 2 doses of RZV vaccine 2-6 months apart. Blood was drawn prevaccination (V1), prior to the second dose (V2) and 4 weeks after second dose (V3). Humoral (anti-gE) and cell-mediated immunity was evaluated, with polyfunctional cells defined as cells producing ≥2 cytokines. RESULTS Among 31 eligible VZV-seronegative SOT patients screened, 23 were enrolled. Median age was 38 years and median time since transplant procedure was 38 years. The most frequent transplant types were liver (35%) and lung (30%). Median anti-gE levels significantly increased from V1 to V3 (p=0001) and V2 to V3 (p<0001), even though only 55% had a positive seroresponse. Median polyfunctional CD4 T-cells counts increased from V1 to V2 (54/10 vs 104/10 cells; p=0041), and from V2 to V3 (380/10; p=0002). Most adverse events were mild with no rejection episodes. CONCLUSION RZV was safe and elicited significant humoral and cellular responses in VZV-seronegative SOT patients, and has the potential to be considered as a preventive strategy against primary varicella.
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Pseudorabies virus glycoprotein gE suppresses interferon-β production via CREB-binding protein degradation. Virus Res 2020; 291:198220. [PMID: 33152381 DOI: 10.1016/j.virusres.2020.198220] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Revised: 10/27/2020] [Accepted: 10/28/2020] [Indexed: 12/24/2022]
Abstract
Cyclic GMP-AMP synthase (cGAS) is a main sensor used to detect microbial DNA in the cytoplasm, which subsequently induces the production of interferon (IFN) via the cGAS/STING/IRF3 signaling pathway, leading to an antiviral response. However, some viruses have evolved multiple strategies to escape this process. Pseudorabies virus (PRV) is a double-stranded DNA virus belonging to the Alphaherpesvirinae subfamily, which can cause serious damage to the porcine industry. Many herpesvirus components have been reported to counteract IFN production, whereas little is known of PRV. In the present study, we found that PRV glycoprotein E (gE) was involved in counteracting cGAS/STING-mediated IFN production. Ectopic expression of gE decreased cGAS/STING-mediated IFN-β promoter activity and the level of mRNA expression. Moreover, gE targeted at or downstream of IRF3 was found to inhibit IFN-β production. However, gE did not affect the phosphorylation, dimerization and nuclear translocation of IRF3. Furthermore, gE is located on the nuclear membrane and could subsequently degrade CREB-binding protein (CBP). MG132, a proteasome inhibitor, decreased CBP degradation and restored the IFN-β production induced by gE. Finally, gE-deleted PRV induced a higher level of IFN-β production and reduced CBP degradation compared to wild-type PRV. Together, these results demonstrate that PRV gE can inhibit cGAS/STING-mediated IFN-β production by degrading CBP to interrupt the enhanced assembly of IRF3 and CBP.
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Abstract
The continuous interactions between host and pathogens during their coevolution have shaped both the immune system and the countermeasures used by pathogens. Natural killer (NK) cells are innate lymphocytes that are considered central players in the antiviral response. Not only do they express a variety of inhibitory and activating receptors to discriminate and eliminate target cells but they can also produce immunoregulatory cytokines to alert the immune system. Reciprocally, several unrelated viruses including cytomegalovirus, human immunodeficiency virus, influenza virus, and dengue virus have evolved a multitude of mechanisms to evade NK cell function, such as the targeting of pathways for NK cell receptors and their ligands, apoptosis, and cytokine-mediated signaling. The studies discussed in this article provide further insights into the antiviral function of NK cells and the pathways involved, their constituent proteins, and ways in which they could be manipulated for host benefit.
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Affiliation(s)
- Mathieu Mancini
- Department of Human Genetics, McGill University, Montreal, Quebec H3A 0C7, Canada;,
- McGill University Research Centre on Complex Traits, McGill University, Montreal, Quebec H3G 0B1, Canada
| | - Silvia M. Vidal
- Department of Human Genetics, McGill University, Montreal, Quebec H3A 0C7, Canada;,
- McGill University Research Centre on Complex Traits, McGill University, Montreal, Quebec H3G 0B1, Canada
- Department of Medicine, McGill University, Montreal, Quebec H4A 3J1, Canada
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Recombinant Glycoprotein E of Varicella Zoster Virus Contains Glycan-Peptide Motifs That Modulate B Cell Epitopes into Discrete Immunological Signatures. Int J Mol Sci 2019; 20:ijms20040954. [PMID: 30813247 PMCID: PMC6412795 DOI: 10.3390/ijms20040954] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Revised: 02/18/2019] [Accepted: 02/19/2019] [Indexed: 12/18/2022] Open
Abstract
A recombinant subunit vaccine (Shingrix®) was recently licensed for use against herpes zoster. This vaccine is based on glycoprotein E (gE) of varicella zoster virus (VZV), the most abundantly expressed protein of VZV, harboring sites for N- and O-linked glycosylation. The subunit vaccine elicits stronger virus-specific CD4+ T cell response as well as antibody B cell response to gE, compared to the currently used live attenuated vaccine (Zostavax®). This situation is at variance with the current notion since a live vaccine, causing an active virus infection, should be far more efficient than a subunit vaccine based on only one single viral glycoprotein. We previously found gE to be heavily glycosylated, not least by numerous clustered O-linked glycans, when it was produced in human fibroblasts. However, in contrast to Zostavax®, which is produced in fibroblasts, the recombinant gE of Shingrix® is expressed in Chinese hamster ovary (CHO) cells. Hence, the glycan occupancy and glycan structures of gE may differ considerably between the two vaccine types. Here, we aimed at (i) defining the glycan structures and positions of recombinant gE and (ii) identifying possible features of the recombinant gE O-glycosylation pattern contributing to the vaccine efficacy of Shingrix®. Firstly, recombinant gE produced in CHO cells (“Shingrix situation”) is more scarcely decorated by O-linked glycans than gE from human fibroblasts (“Zostavax situation”), with respect to glycan site occupancy. Secondly, screening of immunodominant B cell epitopes of gE, using a synthetic peptide library against serum samples from VZV-seropositive individuals, revealed that the O-linked glycan signature promoted binding of IgG antibodies via a decreased number of interfering O-linked glycans, but also via specific O-linked glycans enhancing antibody binding. These findings may, in part, explain the higher protective efficacy of Shingrix®, and can also be of relevance for development of subunit vaccines to other enveloped viruses.
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Petrini S, Iscaro C, Righi C. Antibody Responses to Bovine Alphaherpesvirus 1 (BoHV-1) in Passively Immunized Calves. Viruses 2019; 11:v11010023. [PMID: 30609738 PMCID: PMC6356344 DOI: 10.3390/v11010023] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Revised: 11/28/2018] [Accepted: 11/29/2018] [Indexed: 12/30/2022] Open
Abstract
To date, in countries where infectious bovine rhinotracheitis (IBR) is widespread, its control is associated with deleted marker vaccines. These products lack one or more genes responsible for the synthesis of glycoproteins or enzymes. In Europe, the most widely used marker vaccine is one in which glycoprotein E (gE-) is deleted, and it is marketed in a killed or modified-live form. Using this type of immunization, it is possible to differentiate vaccinated animals (gE-) from those infected or injected with non-deleted (gE+) products using diagnostic tests specific for gE. The disadvantage of using modified-live gE-products is that they may remain latent in immunized animals and be reactivated or excreted following an immunosuppressive stimulus. For this reason, in the last few years, a new marker vaccine became commercially available containing a double deletion related to genes coding for gE and the synthesis of the thymidine-kinase (tk) enzyme, the latter being associated with the reduction of the neurotropism, latency, and reactivation of the vaccine virus. Intramuscularly and intranasally administered marker products induce a humoral immune response; however, the mother-to-calf antibody kinetics after vaccination with marker vaccines is poorly understood. This review discusses several published articles on this topic.
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Affiliation(s)
- Stefano Petrini
- National Reference Laboratory for Infectious Bovine Rhinotracheitis (IBR), Istituto Zooprofilattico Sperimentale Umbria-Marche "Togo Rosati", 06126 Perugia, Italy.
| | - Carmen Iscaro
- National Reference Laboratory for Infectious Bovine Rhinotracheitis (IBR), Istituto Zooprofilattico Sperimentale Umbria-Marche "Togo Rosati", 06126 Perugia, Italy.
| | - Cecilia Righi
- National Reference Laboratory for Infectious Bovine Rhinotracheitis (IBR), Istituto Zooprofilattico Sperimentale Umbria-Marche "Togo Rosati", 06126 Perugia, Italy.
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Vallbracht M, Fuchs W, Klupp BG, Mettenleiter TC. Functional Relevance of the Transmembrane Domain and Cytoplasmic Tail of the Pseudorabies Virus Glycoprotein H for Membrane Fusion. J Virol 2018; 92:e00376-18. [PMID: 29618646 PMCID: PMC5974499 DOI: 10.1128/jvi.00376-18] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Accepted: 03/29/2018] [Indexed: 12/18/2022] Open
Abstract
Herpesvirus membrane fusion depends on the core fusion machinery, comprised of glycoproteins B (gB) and gH/gL. Although gB structurally resembles autonomous class III fusion proteins, it strictly depends on gH/gL to drive membrane fusion. Whether the gH/gL complex needs to be membrane anchored to fulfill its function and which role the gH cytoplasmic (CD) and transmembrane domains (TMD) play in fusion is unclear. While the gH CD and TMD play an important role during infection, soluble gH/gL of herpes simplex virus 1 (HSV-1) seems to be sufficient to mediate cell-cell fusion in transient assays, arguing against an essential contribution of the CD and TMD. To shed more light on this apparent discrepancy, we investigated the role of the CD and TMD of the related alphaherpesvirus pseudorabies virus (PrV) gH. For this purpose, we expressed C-terminally truncated and soluble gH and replaced the TMD with a glycosylphosphatidylinositol (gpi) anchor. We also generated chimeras containing the TMD and/or CD of PrV gD or HSV-1 gH. Proteins were characterized in cell-based fusion assays and during virus infection. Although truncation of the CD resulted in decreased membrane fusion activity, the mutant proteins still supported replication of gH-negative PrV, indicating that the PrV gH CD is dispensable for viral replication. In contrast, PrV gH lacking the TMD, membrane-anchored via a lipid linker, or comprising the PrV gD TMD were nonfunctional, highlighting the essential role of the gH TMD for function. Interestingly, despite low sequence identity, the HSV-1 gH TMD could substitute for the PrV gH TMD, pointing to functional conservation.IMPORTANCE Enveloped viruses depend on membrane fusion for virus entry. While this process can be mediated by only one or two proteins, herpesviruses depend on the concerted action of at least three different glycoproteins. Although gB has features of bona fide fusion proteins, it depends on gH and its complex partner, gL, for fusion. Whether gH/gL prevents premature fusion or actively triggers gB-mediated fusion is unclear, and there are contradictory results on whether gH/gL function requires stable membrane anchorage or whether the ectodomains alone are sufficient. Our results show that in pseudorabies virus gH, the transmembrane anchor plays an essential role for gB-mediated fusion while the cytoplasmic tail is not strictly required.
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Affiliation(s)
- Melina Vallbracht
- Institute of Molecular Virology and Cell Biology, Friedrich-Loeffler-Institut, Greifswald-Insel Riems, Germany
| | - Walter Fuchs
- Institute of Molecular Virology and Cell Biology, Friedrich-Loeffler-Institut, Greifswald-Insel Riems, Germany
| | - Barbara G Klupp
- Institute of Molecular Virology and Cell Biology, Friedrich-Loeffler-Institut, Greifswald-Insel Riems, Germany
| | - Thomas C Mettenleiter
- Institute of Molecular Virology and Cell Biology, Friedrich-Loeffler-Institut, Greifswald-Insel Riems, Germany
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Abstract
Natural killer (NK) cells play an important role in the host response against viral infections and cancer development. They are able to kill virus-infected and tumor cells, and they produce different important cytokines that stimulate the antiviral and antitumor adaptive immune response, particularly interferon gamma. NK cells are of particular importance in herpesvirus infections, which is illustrated by systemic and life-threatening herpesvirus disease symptoms in patients with deficiencies in NK cell activity and by the myriad of reports describing herpesvirus NK cell evasion strategies. The latter is particularly obvious for cytomegaloviruses, but increasing evidence indicates that most, if not all, members of the herpesvirus family suppress NK cell activity to some extent. This review discusses the different NK cell evasion strategies described for herpesviruses and how this knowledge may translate to clinical applications.
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Boesch AW, Kappel JH, Mahan AE, Chu TH, Crowley AR, Osei-Owusu NY, Alter G, Ackerman ME. Enrichment of high affinity subclasses and glycoforms from serum-derived IgG using FcγRs as affinity ligands. Biotechnol Bioeng 2018; 115:1265-1278. [PMID: 29315477 DOI: 10.1002/bit.26545] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Revised: 12/18/2017] [Accepted: 01/03/2018] [Indexed: 12/26/2022]
Abstract
As antibodies continue to gain predominance in drug discovery and development pipelines, efforts to control and optimize their activity in vivo have matured to incorporate sophisticated abilities to manipulate engagement of specific Fc binding partners. Such efforts to promote diverse functional outcomes include modulating IgG-Fc affinity for FcγRs to alternatively potentiate or reduce effector functions, such as antibody-dependent cellular cytotoxicity and phagocytosis. While a number of natural and engineered Fc features capable of eliciting variable effector functions have been demonstrated in vitro and in vivo, elucidation of these important functional relationships has taken significant effort through use of diverse genetic, cellular and enzymatic techniques. As an orthogonal approach, we demonstrate use of FcγR as chromatographic affinity ligands to enrich and therefore simultaneously identify favored binding species from a complex mixture of serum-derived pooled polycloncal human IgG, a load material that contains the natural repertoire of Fc variants and post-translational modifications. The FcγR-enriched IgG was characterized for subclass and glycoform composition and the impact of this bioseparation step on antibody activity was measured in cell-based effector function assays including Natural Killer cell activation and monocyte phagocytosis. This work demonstrates a tractable means to rapidly distinguish complex functional relationships between two or more interacting biological agents by leveraging affinity chromatography followed by secondary analysis with high-resolution biophysical and functional assays and emphasizes a platform capable of surveying diverse natural post-translational modifications that may not be easily produced with high purity or easily accessible with recombinant expression techniques.
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Affiliation(s)
- Austin W Boesch
- Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire
- Zepteon, Inc., Boston, Massachusetts
| | - James H Kappel
- Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire
| | - Alison E Mahan
- Ragon Institute of MGH, MIT, and Harvard University, Cambridge, Massachusetts
| | - Thach H Chu
- Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire
| | - Andrew R Crowley
- Department of Microbiology and Immunology, Geisel School of Medicine, Hanover, New Hampshire
| | - Nana Y Osei-Owusu
- Department of Microbiology and Immunology, Geisel School of Medicine, Hanover, New Hampshire
| | - Galit Alter
- Ragon Institute of MGH, MIT, and Harvard University, Cambridge, Massachusetts
| | - Margaret E Ackerman
- Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire
- Department of Microbiology and Immunology, Geisel School of Medicine, Hanover, New Hampshire
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12
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Dai HS, Griffin N, Bolyard C, Mao HC, Zhang J, Cripe TP, Suenaga T, Arase H, Nakano I, Chiocca EA, Kaur B, Yu J, Caligiuri MA. The Fc Domain of Immunoglobulin Is Sufficient to Bridge NK Cells with Virally Infected Cells. Immunity 2017; 47:159-170.e10. [PMID: 28723548 DOI: 10.1016/j.immuni.2017.06.019] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Revised: 05/23/2017] [Accepted: 06/26/2017] [Indexed: 12/11/2022]
Abstract
Clearance of pathogens or tumor cells by antibodies traditionally requires both Fab and Fc domains of IgG. Here, we show the Fc domain of IgG alone mediates recognition and clearance of herpes simplex virus (HSV1)-infected cells. The human natural killer (NK) cell surface is naturally coated with IgG bound by its Fc domain to the Fcγ receptor CD16a. NK cells utilize the Fc domain of bound IgG to recognize gE, an HSV1-encoded glycoprotein that also binds the Fc domain of IgG but at a site distinct from CD16a. The bridge formed by the Fc domain between the HSV1-infected cell and the NK cell results in NK cell activation and lysis of the HSV1-infected cell in the absence of HSV1-specific antibody in vitro and prevents fatal HSV1 infection in vivo. This mechanism also explains how bacterial IgG-binding proteins regulate NK cell function and may be broadly applicable to Fcγ-receptor-bearing cells.
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Affiliation(s)
- Hong-Sheng Dai
- The Ohio State University Comprehensive Cancer Center, The James Cancer Hospital and Solove Research Institute, Columbus, OH 43210, USA; Division of Hematology, Department of Internal Medicine, College of Medicine, The Ohio State University, Columbus, OH 43205, USA.
| | - Nathaniel Griffin
- The Ohio State University Comprehensive Cancer Center, The James Cancer Hospital and Solove Research Institute, Columbus, OH 43210, USA; Division of Hematology, Department of Internal Medicine, College of Medicine, The Ohio State University, Columbus, OH 43205, USA
| | - Chelsea Bolyard
- Department of Neurological Surgery, The Ohio State University, Columbus, OH 43205, USA
| | - Hsiaoyin Charlene Mao
- The Ohio State University Comprehensive Cancer Center, The James Cancer Hospital and Solove Research Institute, Columbus, OH 43210, USA; Division of Hematology, Department of Internal Medicine, College of Medicine, The Ohio State University, Columbus, OH 43205, USA
| | - Jianying Zhang
- Center for Biostatistics, The Ohio State University, Columbus, OH 43205, USA
| | - Timothy P Cripe
- Center for Childhood Cancer and Blood Diseases, Nationwide Children's Hospital, The Ohio State University, Columbus, OH 43205, USA; Division of Hematology/Oncology/Blood and Marrow Transplantation, Nationwide Children's Hospital, The Ohio State University, Columbus, OH 43205, USA
| | - Tadahiro Suenaga
- Laboratory of Immunochemistry, WPI Immunology Frontier Research Center and Department of Immunochemistry, Research Institute for Microbial Diseases, Osaka University, Osaka 565-0871, Japan
| | - Hisashi Arase
- Laboratory of Immunochemistry, WPI Immunology Frontier Research Center and Department of Immunochemistry, Research Institute for Microbial Diseases, Osaka University, Osaka 565-0871, Japan
| | - Ichiro Nakano
- Neurosurgery, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - E A Chiocca
- Department of Neurosurgery, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Balveen Kaur
- Department of Neurological Surgery, The Ohio State University, Columbus, OH 43205, USA
| | - Jianhua Yu
- The Ohio State University Comprehensive Cancer Center, The James Cancer Hospital and Solove Research Institute, Columbus, OH 43210, USA; Division of Hematology, Department of Internal Medicine, College of Medicine, The Ohio State University, Columbus, OH 43205, USA
| | - Michael A Caligiuri
- The Ohio State University Comprehensive Cancer Center, The James Cancer Hospital and Solove Research Institute, Columbus, OH 43210, USA; Division of Hematology, Department of Internal Medicine, College of Medicine, The Ohio State University, Columbus, OH 43205, USA.
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Bagdonaite I, Nordén R, Joshi HJ, King SL, Vakhrushev SY, Olofsson S, Wandall HH. Global Mapping of O-Glycosylation of Varicella Zoster Virus, Human Cytomegalovirus, and Epstein-Barr Virus. J Biol Chem 2016; 291:12014-28. [PMID: 27129252 DOI: 10.1074/jbc.m116.721746] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2016] [Indexed: 12/27/2022] Open
Abstract
Herpesviruses are among the most complex and widespread viruses, infection and propagation of which depend on envelope proteins. These proteins serve as mediators of cell entry as well as modulators of the immune response and are attractive vaccine targets. Although envelope proteins are known to carry glycans, little is known about the distribution, nature, and functions of these modifications. This is particularly true for O-glycans; thus we have recently developed a "bottom up" mass spectrometry-based technique for mapping O-glycosylation sites on herpes simplex virus type 1. We found wide distribution of O-glycans on herpes simplex virus type 1 glycoproteins and demonstrated that elongated O-glycans were essential for the propagation of the virus. Here, we applied our proteome-wide discovery platform for mapping O-glycosites on representative and clinically significant members of the herpesvirus family: varicella zoster virus, human cytomegalovirus, and Epstein-Barr virus. We identified a large number of O-glycosites distributed on most envelope proteins in all viruses and further demonstrated conserved patterns of O-glycans on distinct homologous proteins. Because glycosylation is highly dependent on the host cell, we tested varicella zoster virus-infected cell lysates and clinically isolated virus and found evidence of consistent O-glycosites. These results present a comprehensive view of herpesvirus O-glycosylation and point to the widespread occurrence of O-glycans in regions of envelope proteins important for virus entry, formation, and recognition by the host immune system. This knowledge enables dissection of specific functional roles of individual glycosites and, moreover, provides a framework for design of glycoprotein vaccines with representative glycosylation.
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Affiliation(s)
- Ieva Bagdonaite
- From the Copenhagen Center for Glycomics, Department of Cellular and Molecular Medicine, University of Copenhagen, 2200 Copenhagen, Denmark and
| | - Rickard Nordén
- the Department of Infectious Diseases, Institute of Biomedicine, University of Gothenburg, 413 45 Gothenburg, Sweden
| | - Hiren J Joshi
- From the Copenhagen Center for Glycomics, Department of Cellular and Molecular Medicine, University of Copenhagen, 2200 Copenhagen, Denmark and
| | - Sarah L King
- From the Copenhagen Center for Glycomics, Department of Cellular and Molecular Medicine, University of Copenhagen, 2200 Copenhagen, Denmark and
| | - Sergey Y Vakhrushev
- From the Copenhagen Center for Glycomics, Department of Cellular and Molecular Medicine, University of Copenhagen, 2200 Copenhagen, Denmark and
| | - Sigvard Olofsson
- the Department of Infectious Diseases, Institute of Biomedicine, University of Gothenburg, 413 45 Gothenburg, Sweden
| | - Hans H Wandall
- From the Copenhagen Center for Glycomics, Department of Cellular and Molecular Medicine, University of Copenhagen, 2200 Copenhagen, Denmark and
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Modulation of host CD59 expression by varicella-zoster virus in human xenografts in vivo. Virology 2016; 491:96-105. [PMID: 26891237 DOI: 10.1016/j.virol.2016.01.019] [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] [Received: 06/26/2015] [Revised: 01/13/2016] [Accepted: 01/26/2016] [Indexed: 01/06/2023]
Abstract
Varicella-zoster virus (VZV) is the causative agent of both chickenpox (varicella) and shingles (zoster). VZV survives host defenses, even with an intact immune system, and disseminates in the host before causing disease. To date, several diverse immunomodulatory strategies used by VZV to undermine host immunity have been identified; however, few studies have addressed the complement evasion strategies used by this virus. Here, we show that expression of CD59, which is a key member of host regulators of complement activation (RCA), is significantly upregulated in response to VZV infection in human T cells and dorsal root ganglia (DRG) but not in human skin xenografts in SCID-hu mice in vivo. This is the first report demonstrating that VZV infection upregulates host CD59 expression in a tissue-specific manner in vivo, which may aid VZV in complement evasion and pathogenesis.
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Suenaga T, Matsumoto M, Arisawa F, Kohyama M, Hirayasu K, Mori Y, Arase H. Sialic Acids on Varicella-Zoster Virus Glycoprotein B Are Required for Cell-Cell Fusion. J Biol Chem 2015; 290:19833-43. [PMID: 26105052 DOI: 10.1074/jbc.m114.635508] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Indexed: 12/28/2022] Open
Abstract
Varicella-zoster virus (VZV) is a member of the human Herpesvirus family that causes varicella (chicken pox) and zoster (shingles). VZV latently infects sensory ganglia and is also responsible for encephalomyelitis. Myelin-associated glycoprotein (MAG), a member of the sialic acid (SA)-binding immunoglobulin-like lectin family, is mainly expressed in neural tissues. VZV glycoprotein B (gB) associates with MAG and mediates membrane fusion during VZV entry into host cells. The SA requirements of MAG when associating with its ligands vary depending on the specific ligand, but it is unclear whether the SAs on gB are involved in the association with MAG. In this study, we found that SAs on gB are essential for the association with MAG as well as for membrane fusion during VZV infection. MAG with a point mutation in the SA-binding site did not bind to gB and did not mediate cell-cell fusion or VZV entry. Cell-cell fusion and VZV entry mediated by the gB-MAG interaction were blocked by sialidase treatment. N-glycosylation or O-glycosylation inhibitors also inhibited the fusion and entry mediated by gB-MAG interaction. Furthermore, gB with mutations in N-glycosylation sites, i.e. asparagine residues 557 and 686, did not associate with MAG, and the cell-cell fusion efficiency was low. Fusion between the viral envelope and cellular membrane is essential for host cell entry by herpesviruses. Therefore, these results suggest that SAs on gB play important roles in MAG-mediated VZV infection.
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Affiliation(s)
- Tadahiro Suenaga
- From the Department of Immunochemistry, Research Institute for Microbial Diseases and Laboratory of Immunochemistry, WPI Immunology Frontier Research Center, Osaka University, Suita, Osaka 565-0871, Japan, and
| | - Maki Matsumoto
- From the Department of Immunochemistry, Research Institute for Microbial Diseases and Laboratory of Immunochemistry, WPI Immunology Frontier Research Center, Osaka University, Suita, Osaka 565-0871, Japan, and
| | - Fuminori Arisawa
- From the Department of Immunochemistry, Research Institute for Microbial Diseases and
| | - Masako Kohyama
- From the Department of Immunochemistry, Research Institute for Microbial Diseases and Laboratory of Immunochemistry, WPI Immunology Frontier Research Center, Osaka University, Suita, Osaka 565-0871, Japan, and
| | - Kouyuki Hirayasu
- From the Department of Immunochemistry, Research Institute for Microbial Diseases and Laboratory of Immunochemistry, WPI Immunology Frontier Research Center, Osaka University, Suita, Osaka 565-0871, Japan, and
| | - Yasuko Mori
- the Division of Clinical Virology, Center for Infectious Diseases, Kobe University Graduate School of Medicine, Kobe, Hyogo, 650-0017, Japan
| | - Hisashi Arase
- From the Department of Immunochemistry, Research Institute for Microbial Diseases and Laboratory of Immunochemistry, WPI Immunology Frontier Research Center, Osaka University, Suita, Osaka 565-0871, Japan, and
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16
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The herpes virus Fc receptor gE-gI mediates antibody bipolar bridging to clear viral antigens from the cell surface. PLoS Pathog 2014; 10:e1003961. [PMID: 24604090 PMCID: PMC3946383 DOI: 10.1371/journal.ppat.1003961] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2013] [Accepted: 01/16/2014] [Indexed: 11/19/2022] Open
Abstract
The Herpes Simplex Virus 1 (HSV-1) glycoprotein gE-gI is a transmembrane Fc receptor found on the surface of infected cells and virions that binds human immunoglobulin G (hIgG). gE-gI can also participate in antibody bipolar bridging (ABB), a process by which the antigen-binding fragments (Fabs) of the IgG bind a viral antigen while the Fc binds to gE-gI. IgG Fc binds gE-gI at basic, but not acidic, pH, suggesting that IgG bound at extracellular pH by cell surface gE-gI would dissociate and be degraded in acidic endosomes/lysosomes if endocytosed. The fate of viral antigens associated with gE-gI-bound IgG had been unknown: they could remain at the cell surface or be endocytosed with IgG. Here, we developed an in vitro model system for ABB and investigated the trafficking of ABB complexes using 4-D confocal fluorescence imaging of ABB complexes with transferrin or epidermal growth factor, well-characterized intracellular trafficking markers. Our data showed that cells expressing gE-gI and the viral antigen HSV-1 gD endocytosed anti-gD IgG and gD in a gE-gI-dependent process, resulting in lysosomal localization. These results suggest that gE-gI can mediate clearance of infected cell surfaces of anti-viral host IgG and viral antigens to evade IgG-mediated responses, representing a general mechanism for viral Fc receptors in immune evasion and viral pathogenesis.
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Cortese M, Calò S, D'Aurizio R, Lilja A, Pacchiani N, Merola M. Recombinant human cytomegalovirus (HCMV) RL13 binds human immunoglobulin G Fc. PLoS One 2012; 7:e50166. [PMID: 23226246 PMCID: PMC3511460 DOI: 10.1371/journal.pone.0050166] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2012] [Accepted: 10/22/2012] [Indexed: 01/05/2023] Open
Abstract
The human cytomegalovirus (HCMV) protein RL13 has recently been described to be present in all primary isolates but rapidly mutated in culture adapted viruses. Although these data suggest a crucial role for this gene product in HCMV primary infection, no function has so far been assigned to this protein. Working with RL13 expressed in isolation in transfected human epithelial cells, we demonstrated that recombinant RL13 from the clinical HCMV isolates TR and Merlin have selective human immunoglobulin (Ig)-binding properties towards IgG1 and IgG2 subtypes. An additional Fc binding protein, RL12, was also identified as an IgG1 and IgG2 binding protein but not further characterized. The glycoprotein RL13 trafficked to the plasma membrane where it bound and internalized exogenous IgG or its constant fragment (Fcγ). Analysis of RL13 ectodomain mutants suggested that the RL13 Ig-like domain is responsible for the Fc binding activity. Ligand-dependent internalization relied on a YxxL endocytic motif located in the C-terminal tail of RL13. Additionally, we showed that the tyrosine residue could be replaced by phenylalanine but not by alanine, indicating that the internalization signal was independent from phosphorylation events. In sum, RL13 binds human IgG and may contribute to HCMV immune evasion in the infected host, but this function does not readily explain the instability of the RL13 gene during viral propagation in cultured cells.
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Affiliation(s)
| | | | | | - Anders Lilja
- Novartis Vaccines and Diagnostics, Cambridge, Massachusetts, United States of America
| | | | - Marcello Merola
- Novartis Vaccines and Diagnostics, Siena, Italy
- Department of Structural and Functional Biology, University of Naples “Federico II”, Naples, Italy
- * E-mail:
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Simian varicella virus gene expression during acute and latent infection of rhesus macaques. J Neurovirol 2011; 17:600-12. [PMID: 22052378 DOI: 10.1007/s13365-011-0057-y] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2011] [Revised: 09/26/2011] [Accepted: 10/06/2011] [Indexed: 10/15/2022]
Abstract
Varicella zoster virus (VZV) is a neurotropic α-herpesvirus that causes chickenpox during primary infection and establishes latency in sensory ganglia. Reactivation of VZV results in herpes zoster and other neurological complications. Our understanding of the VZV transcriptome during acute and latent infection in immune competent individuals remains incomplete. Infection of rhesus macaques with the homologous simian varicella virus (SVV) recapitulates the hallmarks of VZV infection. We therefore characterized the SVV transcriptome by quantitative real-time reverse transcriptase PCR during acute infection in bronchial alveolar lavage (BAL) cells and peripheral blood mononuclear cells, and during latency in sensory ganglia obtained from the same rhesus macaques. During acute infection, all known SVV open reading frames (ORFs) were detected, and the most abundantly expressed ORFs are involved in virus replication and assembly such as the transcriptional activator ORF 63 and the structural proteins ORF 41 and ORF 49. In contrast, latent SVV gene expression is highly restricted. ORF 61, a viral transactivator and latency-associated transcript, is the most prevalent transcript detected in sensory ganglia. We also detected ORFs A, B, 4, 10, 63, 64, 65, 66, and 68 though significantly less frequently than ORF 61. This comprehensive analysis has revealed genes that potentially play a role in the establishment and/or maintenance of SVV latency.
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19
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Immunization with a vaccine combining herpes simplex virus 2 (HSV-2) glycoprotein C (gC) and gD subunits improves the protection of dorsal root ganglia in mice and reduces the frequency of recurrent vaginal shedding of HSV-2 DNA in guinea pigs compared to immunization with gD alone. J Virol 2011; 85:10472-86. [PMID: 21813597 DOI: 10.1128/jvi.00849-11] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Attempts to develop a vaccine to prevent genital herpes simplex virus 2 (HSV-2) disease have been only marginally successful, suggesting that novel strategies are needed. Immunization with HSV-2 glycoprotein C (gC-2) and gD-2 was evaluated in mice and guinea pigs to determine whether adding gC-2 to a gD-2 subunit vaccine would improve protection by producing antibodies that block gC-2 immune evasion from complement. Antibodies produced by gC-2 immunization blocked the interaction between gC-2 and complement C3b, and passive transfer of gC-2 antibody protected complement-intact mice but not C3 knockout mice against HSV-2 challenge, indicating that gC-2 antibody is effective, at least in part, because it prevents HSV-2 evasion from complement. Immunization with gC-2 also produced neutralizing antibodies that were active in the absence of complement; however, the neutralizing titers were higher when complement was present, with the highest titers in animals immunized with both antigens. Animals immunized with the gC-2-plus-gD-2 combination had robust CD4+ T-cell responses to each immunogen. Multiple disease parameters were evaluated in mice and guinea pigs immunized with gC-2 alone, gD-2 alone, or both antigens. In general, gD-2 outperformed gC-2; however, the gC-2-plus-gD-2 combination outperformed gD-2 alone, particularly in protecting dorsal root ganglia in mice and reducing recurrent vaginal shedding of HSV-2 DNA in guinea pigs. Therefore, the gC-2 subunit antigen enhances a gD-2 subunit vaccine by stimulating a CD4+ T-cell response, by producing neutralizing antibodies that are effective in the absence and presence of complement, and by blocking immune evasion domains that inhibit complement activation.
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20
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Thomsson E, Persson L, Grahn A, Snäll J, Ekblad M, Brunhage E, Svensson F, Jern C, Hansson GC, Bäckström M, Bergström T. Recombinant glycoprotein E produced in mammalian cells in large-scale as an antigen for varicella-zoster-virus serology. J Virol Methods 2011; 175:53-9. [PMID: 21540058 DOI: 10.1016/j.jviromet.2011.04.014] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2011] [Revised: 04/11/2011] [Accepted: 04/14/2011] [Indexed: 11/25/2022]
Abstract
A recombinant glycoprotein E (gE) from varicella-zoster virus (VZV) was generated and produced in Chinese Hamster Ovary (CHO) cells, in the development of a specific antigen for analysis of IgG antibodies to VZV. Several stable gE-secreting clones were established and one clone was adapted to growth in serum-free suspension culture. When the cells were cultured in a perfusion bioreactor, gE was secreted into the medium, from where it could be easily purified. The recombinant gE was then evaluated as a serological antigen in ELISA. When compared to a conventional whole virus antigen, the VZV gE showed similar results in ELISA-based seroprevalence studies of 854 samples derived from blood donors, students, ischemic stroke patients and their controls, including samples with border-line results in previous analyses. Eight samples (0.9%) were discordant, all being IgG-negative by the VZV gE ELISA and positive by the whole virus ELISA. The sensitivity and specificity of the VZV gE ELISA were 99.9% and 100%, respectively, compared to 100% and 88.9% for the VZV whole virus ELISA. The elderly subjects showed similar reactivities to both antigens, while VZV gE gave lower signals in the younger cohorts, suggesting that antibodies to gE may increase with age. It was concluded that the recombinant VZV gE from CHO cells was suitable as a serological antigen for the detection of IgG antibodies specific for VZV.
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Affiliation(s)
- Elisabeth Thomsson
- Mammalian Protein Expression Core Facility, Sahlgrenska Academy, University of Gothenburg, Box 440, 405 30 Gothenburg, Sweden
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Mutagenesis of varicella-zoster virus glycoprotein I (gI) identifies a cysteine residue critical for gE/gI heterodimer formation, gI structure, and virulence in skin cells. J Virol 2011; 85:4095-110. [PMID: 21345964 DOI: 10.1128/jvi.02596-10] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Varicella-zoster virus (VZV) is the alphaherpesvirus that causes chicken pox (varicella) and shingles (zoster). The two VZV glycoproteins gE and gI form a heterodimer that mediates efficient cell-to-cell spread. Deletion of gI yields a small-plaque-phenotype virus, ΔgI virus, which is avirulent in human skin using the xenograft model of VZV pathogenesis. In the present study, 10 mutant viruses were generated to determine which residues were required for the typical function of gI. Three phosphorylation sites in the cytoplasmic domain of gI were not required for VZV virulence in vivo. Two deletion mutants mapped a gE binding region in gI to residues 105 to 125. A glycosylation site, N116, in this region did not affect virulence. Substitution of four cysteine residues highly conserved in the Alphaherpesvirinae established that C95 is required for gE/gI heterodimer formation. The C95A and Δ105-125 (with residues 105 to 125 deleted) viruses had small-plaque phenotypes with reduced replication kinetics in vitro similar to those of the ΔgI virus. The Δ105-125 virus was avirulent for human skin in vivo. In contrast, the C95A mutant replicated in vivo but with significantly reduced kinetics compared to those of the wild-type virus. In addition to abolished gE/gI heterodimer formation, gI from the C95A or the Δ105-125 mutant was not recognized by monoclonal antibodies that detect the canonical conformation of gI, demonstrating structural disruption of gI in these viruses. This alteration prevented gI incorporation into virus particles. Thus, residues C95 and 105 to 125 are critical for gI structure required for gE/gI heterodimer formation, virion incorporation, and ultimately, effective viral spread in human skin.
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22
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The herpes simplex virus 1 IgG fc receptor blocks antibody-mediated complement activation and antibody-dependent cellular cytotoxicity in vivo. J Virol 2011; 85:3239-49. [PMID: 21228231 DOI: 10.1128/jvi.02509-10] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Herpes simplex virus 1 (HSV-1) glycoprotein E (gE) mediates cell-to-cell spread and functions as an IgG Fc receptor (FcγR) that blocks the Fc domain of antibody targeting the virus or infected cell. Efforts to assess the functions of the HSV-1 FcγR in vivo have been hampered by difficulties in preparing an FcγR-negative strain that is relatively intact for spread. Here we report the FcγR and spread phenotypes of NS-gE264, which is a mutant strain that has four amino acids inserted after gE residue 264. The virus is defective in IgG Fc binding yet causes zosteriform disease in the mouse flank model that is only minimally reduced compared with wild-type and the rescue strains. The presence of zosteriform disease suggests that NS-gE264 spread functions are well maintained. The HSV-1 FcγR binds the Fc domain of human, but not murine IgG; therefore, to assess FcγR functions in vivo, mice were passively immunized with human IgG antibody to HSV. When antibody was inoculated intraperitoneally 20 h prior to infection or shortly after virus reached the dorsal root ganglia, disease severity was significantly reduced in mice infected with NS-gE264, but not in mice infected with wild-type or rescue virus. Studies of C3 knockout mice and natural killer cell-depleted mice demonstrated that the HSV-1 FcγR blocked both IgG Fc-mediated complement activation and antibody-dependent cellular cytotoxicity. Therefore, the HSV-1 FcγR promotes immune evasion from IgG Fc-mediated activities and likely contributes to virulence at times when antibody is present, such as during recurrent infections.
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The insulin degrading enzyme binding domain of varicella-zoster virus (VZV) glycoprotein E is important for cell-to-cell spread and VZV infectivity, while a glycoprotein I binding domain is essential for infection. Virology 2009; 386:270-9. [PMID: 19233447 DOI: 10.1016/j.virol.2009.01.023] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2008] [Revised: 01/06/2009] [Accepted: 01/09/2009] [Indexed: 11/20/2022]
Abstract
Varicella-zoster virus (VZV) glycoprotein E (gE) interacts with glycoprotein I and with insulin degrading enzyme (IDE), which is a receptor for the virus. We found that a VZV gE deletion mutant could only be grown in cells expressing gE. Expression of VZV gE on the surface of cells did not interfere with VZV infection. HSV deleted for gE is impaired for cell-to-cell spread; VZV gE could not complement this activity in an HSV gE null mutant. VZV lacking the IDE binding domain of gE grew to peak titers nearly equivalent to parental virus; however, it was impaired for cell-to-cell spread and for infectivity with cell-free virus. VZV deleted for a region of gE that binds glycoprotein I could not replicate in cell culture unless grown in cells expressing gE. We conclude that the IDE binding domain is important for efficient cell-to-cell spread and infectivity of cell-free virus.
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Deletion of the first cysteine-rich region of the varicella-zoster virus glycoprotein E ectodomain abolishes the gE and gI interaction and differentially affects cell-cell spread and viral entry. J Virol 2008; 83:228-40. [PMID: 18945783 DOI: 10.1128/jvi.00913-08] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Varicella-zoster virus (VZV) glycoprotein E (gE) is the most abundant glycoprotein in infected cells and, in contrast to those of other alphaherpesviruses, is essential for viral replication. The gE ectodomain contains a unique N-terminal region required for viral replication, cell-cell spread, and secondary envelopment; this region also binds to the insulin-degrading enzyme (IDE), a proposed VZV receptor. To identify new functional domains of the gE ectodomain, the effect of mutagenesis of the first cysteine-rich region of the gE ectodomain (amino acids 208 to 236) was assessed using VZV cosmids. Deletion of this region was compatible with VZV replication in vitro, but cell-cell spread of the rOka-DeltaCys mutant was reduced significantly. Deletion of the cysteine-rich region abolished the binding of the mutant gE to gI but not to IDE. Preventing gE binding to gI altered the pattern of gE expression at the plasma membrane of infected cells and the posttranslational maturation of gI and its incorporation into viral particles. In contrast, deletion of the first cysteine-rich region did not affect viral entry into human tonsil T cells in vitro or into melanoma cells infected with cell-free VZV. These experiments demonstrate that gE/gI heterodimer formation is essential for efficient cell-cell spread and incorporation of gI into viral particles but that it is dispensable for infectious varicella-zoster virion formation and entry into target cells. Blocking gE binding to gI resulted in severe impairment of VZV infection of human skin xenografts in SCIDhu mice in vivo, documenting the importance of cell fusion mediated by this complex for VZV virulence in skin.
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25
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The human cytomegalovirus Fc receptor gp68 binds the Fc CH2-CH3 interface of immunoglobulin G. J Virol 2008; 82:3490-9. [PMID: 18216124 DOI: 10.1128/jvi.01476-07] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Recognition of immunoglobulin G (IgG) by surface receptors for the Fc domain of immunoglobulin G (Fcgamma), FcgammaRs, can trigger both humoral and cellular immune responses. Two human cytomegalovirus (HCMV)-encoded type I transmembrane receptors with Fcgamma-binding properties (vFcgammaRs), gp34 and gp68, have been identified on the surface of HCMV-infected cells and are assumed to confer protection against IgG-mediated immunity. Here we show that Fcgamma recognition by both vFcgammaRs occurs independently of N-linked glycosylation of Fcgamma, in contrast with the properties of host FcgammaRs. To gain further insight into the interaction with Fcgamma, truncation mutants of the vFcgammaR gp68 ectodomain were probed for Fcgamma binding, resulting in localization of the Fcgamma binding site on gp68 to residues 71 to 289, a region including an immunoglobulin-like domain. Gel filtration and biosensor binding experiments revealed that, unlike host FcgammaRs but similar to the herpes simplex virus type 1 (HSV-1) Fc receptor gE-gI, gp68 binds to the C(H)2-C(H)3 interdomain interface of the Fcgamma dimer with a nanomolar affinity and a 2:1 stoichiometry. Unlike gE-gI, which binds Fcgamma at the slightly basic pH of the extracellular milieu but not at the acidic pH of endosomes, the gp68/Fcgamma complex is stable at pH values from 5.6 to pH 8.1. These data indicate that the mechanistic details of Fc binding by HCMV gp68 differ from those of host FcgammaRs and from that of HSV-1 gE-gI, suggesting distinct functional and recognition properties.
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26
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Egress of light particles among filopodia on the surface of Varicella-Zoster virus-infected cells. J Virol 2008; 82:2821-35. [PMID: 18184710 DOI: 10.1128/jvi.01821-07] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Varicella-zoster virus (VZV) is renowned for its very low titer when grown in cultured cells. There remains no single explanation for the low infectivity. In this study, viral particles on the surfaces of infected cells were examined by several imaging technologies. Few surface particles were detected at 48 h postinfection (hpi), but numerous particles were observed at 72 and 96 hpi. At 72 hpi, 75% of the particles resembled light (L) particles, i.e., envelopes without capsids. By 96 hpi, 85% of all particles resembled L particles. Subsequently, the envelopes of complete virions and L particles were investigated to determine their glycoprotein constituents. Glycoproteins gE, gI, and gB were detected in the envelopes of both types of particles in similar numbers; i.e., there appeared to be no difference in the glycoprotein content of the L particles. The viral particles emerged onto the cell surface amid actin-based filopodia, which were present in abundance within viral highways. Viral particles were easily detected at the base of and along the exterior surfaces of the filopodia. VZV particles were not detected within filopodia. In short, these results demonstrate that VZV infection of cultured cells produces a larger proportion of aberrant coreless particles than has been seen with any other previously examined alphaherpesvirus. Further, these results suggested a major disassociation between capsid formation and envelopment as an explanation for the invariably low VZV titer in cultured cells.
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Li Q, Krogmann T, Ali MA, Tang WJ, Cohen JI. The amino terminus of varicella-zoster virus (VZV) glycoprotein E is required for binding to insulin-degrading enzyme, a VZV receptor. J Virol 2007; 81:8525-32. [PMID: 17553876 PMCID: PMC1951364 DOI: 10.1128/jvi.00286-07] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Varicella-zoster virus (VZV) glycoprotein E (gE) is required for VZV infection. Although gE is well conserved among alphaherpesviruses, the amino terminus of VZV gE is unique. Previously, we showed that gE interacts with insulin-degrading enzyme (IDE) and facilitates VZV infection and cell-to-cell spread of the virus. Here we define the region of VZV gE required to bind IDE. Deletion of amino acids 32 to 71 of gE, located immediately after the predicted signal peptide, resulted in loss of the ability of gE to bind IDE. A synthetic peptide corresponding to amino acids 24 to 50 of gE blocked its interaction with IDE in a concentration-dependent manner. However, a chimeric gE in which amino acids 1 to 71 of VZV gE were fused to amino acids 30 to 545 of herpes simplex virus type 2 gE did not show an increased level of binding to IDE compared with that of full-length HSV gE. Thus, amino acids 24 to 71 of gE are required for IDE binding, and the secondary structure of gE is critical for the interaction. VZV gE also forms a heterodimer with glycoprotein gI. Deletion of amino acids 163 to 208 of gE severely reduced its ability to form a complex with gI. The amino portion of IDE, as well an IDE mutant in the catalytic domain of the protein, bound to gE. Therefore, distinct motifs of VZV gE are important for binding to IDE or to gI.
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Affiliation(s)
- Qingxue Li
- Laboratory of Clinical Infectious Diseases, National Institutes of Health, 10 Center Drive, Bethesda, MD 20892, USA
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28
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Al-Mubarak A, Simon J, Coats C, Okemba JD, Burton MD, Chowdhury SI. Glycoprotein E (gE) specified by bovine herpesvirus type 5 (BHV-5) enables trans-neuronal virus spread and neurovirulence without being a structural component of enveloped virions. Virology 2007; 365:398-409. [PMID: 17477950 DOI: 10.1016/j.virol.2007.03.040] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2007] [Revised: 02/26/2007] [Accepted: 03/21/2007] [Indexed: 11/29/2022]
Abstract
Bovine herpesvirus 5 (BHV-5) is a neurovirulent alpha-herpesvirus that causes fatal encephalitis in calves. We previously demonstrated that deletion of a glycine-rich epitope in the gE ectodomain dramatically reduced BHV-5 neurovirulence. To investigate the role of gE cytoplasmic tail sequences in the neuropathogenesis of BHV-5 in rabbits, we constructed a BHV-5gE recombinant virus with a short residual cytoplasmic domain lacking the YXXL motifs and the acidic (BHV-5gEAm480). In vitro, BHV-5gEAm480 produced on the average smaller plaques, compared with wild-type BHV-5, but it produced on the average substantially larger plaques than the gE ORF-deleted BHV-5. The truncated gE was not phosphorylated, and was not endocytosed from the cell surface. Importantly, the truncated gE was not incorporated into enveloped infectious virions, but its glycosylation and interaction with gI were not affected. In a rabbit model of infection, the BHV-5gEAm480 remained highly virulent, while the gE-null virus was avirulent. The gEAm480 mutant virus invaded most of the central nervous system (CNS) structures that are invaded by the wild-type BHV-5. The number of neurons infected by BHV-5gEAm480 was very similar to the number infected by BHV-5 wild-type and gEAm480-rescued viruses. Collectively, the results suggest that gE functions in transsynaptic transmission of BHV-5 and neurovirulence without being a structural component of the virion particle.
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Affiliation(s)
- A Al-Mubarak
- Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS 66506, USA
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29
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Desplanques AS, Nauwynck HJ, Tilleman K, Deforce D, Favoreel HW. Tyrosine phosphorylation and lipid raft association of pseudorabies virus glycoprotein E during antibody-mediated capping. Virology 2007; 362:60-6. [PMID: 17240415 DOI: 10.1016/j.virol.2006.12.018] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2006] [Revised: 10/04/2006] [Accepted: 12/12/2006] [Indexed: 10/23/2022]
Abstract
In specific cell types infected with the alphaherpesviruses herpes simplex virus and pseudorabies virus (PRV), addition of virus-specific antibodies results in redistribution of cell-surface-anchored viral proteins. This redistribution is triggered by the viral protein gE and consists of the directional movement of the antibody-antigen complexes to one pole of the cell. This viral capping process has been associated with increased antibody-resistant virus spread and strongly resembles immunoreceptor capping, a process that is crucial in activation of different immune cells (e.g. capping of Fcgamma-receptors, B and T cell receptors). Here, we report that the PRV gE-mediated viral capping process results in increased Src kinase-mediated tyrosine phosphorylation of the cytoplasmic domain of gE and that a fraction of gE associates with lipid rafts, all very reminiscent of immunoreceptor capping. These results provide evidence that gE-mediated capping is a viral mimicry of immunoreceptor capping.
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Affiliation(s)
- Ann S Desplanques
- Department of Virology, Parasitology and Immunology, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium.
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30
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Zapata HJ, Nakatsugawa M, Moffat JF. Varicella-zoster virus infection of human fibroblast cells activates the c-Jun N-terminal kinase pathway. J Virol 2006; 81:977-90. [PMID: 17079291 PMCID: PMC1797429 DOI: 10.1128/jvi.01470-06] [Citation(s) in RCA: 218] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The transcription factors ATF-2 and c-Jun are important for transactivation of varicella-zoster virus (VZV) genes. c-Jun is activated by the c-Jun N-terminal kinase (JNK), a member of the mitogen-activated protein kinase pathway that responds to stress and cytokines. To study the effects of VZV on this pathway, confluent human foreskin fibroblasts were infected with cell-associated VZV for 1 to 4 days. Immunoblots showed that phosphorylated JNK and c-Jun levels increased in VZV-infected cells, and kinase assays determined that phospho-JNK was active. Phospho-JNK was detected after 24 h, and levels rose steadily over 4 days in parallel with accumulation of VZV antigen. The two main activators of JNK are MKK4 and MKK7, and levels of their active, phosphorylated forms also increased. The competitive inhibitor of JNK, SP600125, caused a dose-dependent reduction in VZV yield (50% effective concentration, congruent with 8 microM). Specificity was verified by immunoblotting; phospho-c-Jun was eliminated by 18 microM SP600125 in VZV-infected cells. Immunofluorescent confocal microscopy showed that phospho-c-Jun and most of phospho-JNK were in the nuclei of VZV-infected cells; some phospho-JNK was in the cytoplasm. MKK4, MKK7, JNK, and phospho-JNK were detected by immunoblotting in purified preparations of VZV virions, but c-Jun was absent. JNK was located in the virion tegument, as determined by biochemical fractionation and immunogold transmission electron microscopy. Overall, these results demonstrate the importance of the JNK pathway for VZV replication and advance the idea that JNK is a useful drug target against VZV.
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Affiliation(s)
- Heidi J Zapata
- Department of Microbiology and Immunology, State University of New York Upstate Medical University, 750 E. Adams St., Syracuse, NY 13210, USA
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31
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Berarducci B, Ikoma M, Stamatis S, Sommer M, Grose C, Arvin AM. Essential functions of the unique N-terminal region of the varicella-zoster virus glycoprotein E ectodomain in viral replication and in the pathogenesis of skin infection. J Virol 2006; 80:9481-96. [PMID: 16973553 PMCID: PMC1617235 DOI: 10.1128/jvi.00533-06] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Varicella-zoster virus (VZV) glycoprotein E (gE) is a multifunctional protein important for cell-cell spread, envelopment, and possibly entry. In contrast to other alphaherpesviruses, gE is essential for VZV replication. Interestingly, the N-terminal region of gE, comprised of amino acids 1 to 188, was shown not to be conserved in the other alphaherpesviruses by bioinformatics analysis. Mutational analysis was performed to investigate the functions associated with this unique gE N-terminal region. Linker insertions, serine-to-alanine mutations, and deletions were introduced in the gE N-terminal region in the VZV genome, and the effects of these mutations on virus replication and cell-cell spread, gE trafficking and localization, virion formation, and replication in vivo in the skin were analyzed. In summary, mutagenesis of the gE N-terminal region identified a new functional region in the VZV gE ectodomain essential for cell-cell spread and the pathogenesis of VZV skin tropism and demonstrated that different subdomains of the unique N-terminal region had specific roles in viral replication, cell-cell spread, and secondary envelopment.
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Affiliation(s)
- Barbara Berarducci
- Department of Pediatrics and Microbiology, Stanford University School of Medicine, 300 Pasteur Dr., Rm G312, Stanford, CA 94305-5208, USA.
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Favoreel HW, Van Minnebruggen G, Van de Walle GR, Ficinska J, Nauwynck HJ. Herpesvirus interference with virus-specific antibodies: bridging antibodies, internalizing antibodies, and hiding from antibodies. Vet Microbiol 2005; 113:257-63. [PMID: 16326036 DOI: 10.1016/j.vetmic.2005.11.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Herpesviruses have developed different tools to thwart efficient antibody-dependent neutralisation and lysis of virions and elimination of infected cells. This overview will briefly summarize different of these tools, including (i) viral Fc receptors and the resulting process of antibody bridging, (ii) internalization of individual viral proteins and clustered antibody-antigen complexes from the plasma membrane of infected cells, and (iii) directed egress of virus particles to sites of intimate cell-cell contact that are difficult to access for antibodies.
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Affiliation(s)
- Herman W Favoreel
- Laboratory of Virology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium
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Budt M, Reinhard H, Bigl A, Hengel H. Herpesviral Fcgamma receptors: culprits attenuating antiviral IgG? Int Immunopharmacol 2005; 4:1135-48. [PMID: 15251110 PMCID: PMC7173100 DOI: 10.1016/j.intimp.2004.05.020] [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: 03/30/2004] [Revised: 05/17/2004] [Accepted: 05/28/2004] [Indexed: 12/18/2022]
Abstract
Production of IgG in response to virus infection is central to antiviral immune effector functions and a hallmark of B cell memory. Antiviral antibodies (Abs) recognising viral glycoproteins or protein antigen displayed on the surface of virions or virus-infected cells are crucial in rendering the virus noninfectious and in eliminating viruses or infected cells, either acting alone or in conjunction with complement. In many instances, passive transfer of Abs is sufficient to protect from viral infection. Herpesviruses (HV) are equipped with a large array of immunomodulatory functions which increase the efficiency of infection by dampening the antiviral immunity. Members of the α- and β-subfamily of the Herpesviridae are distinct in encoding transmembrane glycoproteins which selectively bind IgG via its Fc domain. The Fc-binding proteins constitute viral Fcγ receptors (vFcγRs) which are expressed on the cell surface of infected cells. Moreover, vFcγRs are abundantly incorporated into the envelope of virions. Despite their molecular and structural heterogeneity, the vFcγRs generally interfere with IgG-mediated effector functions like antibody (Ab)-dependent cellular cytolysis, complement activation and neutralisation of infectivity of virions. vFcγRs may thus contribute to the limited therapeutic potency of antiherpesviral IgG in clinical settings. A detailed molecular understanding of vFcγRs opens up the possibility to design recombinant IgG molecules resisting vFcγRs. Engineering IgG with a better antiviral efficiency represents a new therapeutic option against herpesviral diseases.
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Affiliation(s)
| | | | | | - Hartmut Hengel
- Corresponding author: Tel.: +49-1888-754-2502; fax: +49-1888-754-2328.
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Al-Mubarak A, Chowdhury SI. In the absence of glycoprotein I (gI), gE determines bovine herpesvirus type 5 neuroinvasiveness and neurovirulence. J Neurovirol 2005; 10:233-43. [PMID: 15371153 DOI: 10.1080/13550280490463514] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Bovine herpesvirus type 5 (BHV-5) is an alphaherpesvirus that causes fatal encephalitis in calves. Envelope glycoproteins E (gE) and gI of alphaherpesviruses are important for the pathogenesis in vivo. Previously the authors determined that BHV-5 gE is important for BHV-5 neurovirulence. To determine the role of gI in BHV-5 neurovirulence, the authors have constructed gI-deleted and gI-revertant BHV-5 and analyzed their neuropathogenic properties in a rabbit seizure model. Following intranasal infection, 40% of the rabbits infected with the gI-deleted virus showed severe neurological signs. gI-deleted BHV-5 invaded all the central nervous system (CNS) structures invaded by the gI-revertant BHV-5; however, the number of neurons infected by the gI-deleted virus was similar or slightly reduced (two to four fold). Thus, the gI-deleted virus retained significant neurovirulence and/or neuroinvasive properties when compared with the gE-deleted BHV-5. Pulse-chase analysis revealed that the gE of gI-deleted virus was processed to a larger and a diffused 94- to 100-kDa protein (instead of 94 kDa). The 94- to 100-kDa protein was processed in the Golgi with delayed kinetics but it was endoglycosidase H (EndoH) resistant. In cells infected with gI-deleted virus, there was a reduction in cell-surface gE expression compared to wild-type, which correlated to reduced amount of gE processed in the Golgi. The authors believe that in the absence of gI, BHV-5 gE is sufficient for BHV-5 neurovirulence.
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Affiliation(s)
- A Al-Mubarak
- Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan 66506, USA
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35
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Sauerbrei A, Färber I, Brandstädt A, Schacke M, Wutzler P. Immunofluorescence test for sensitive detection of varicella-zoster virus-specific IgG: an alternative to fluorescent antibody to membrane antigen test. J Virol Methods 2004; 119:25-30. [PMID: 15109817 DOI: 10.1016/j.jviromet.2004.02.012] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2003] [Revised: 02/09/2004] [Accepted: 02/18/2004] [Indexed: 01/11/2023]
Abstract
A highly sensitive indirect fluorescence antibody test (IFAT) has been developed on the basis of varicella-zoster virus (VZV)-infected human lung carcinoma (A549) cells and evaluated for the determination of immunity to VZV. Different serum panels with negative, low, moderate or high anti-VZV IgG levels detected by the fluorescent antibody to membrane antigen (FAMA) assay were investigated. As a result, the sensitivity and the specificity of IFAT were 100% compared to FAMA test. In anti-VZV IgG-positive sera, a significant correlation between the results of FAMA procedure and IFAT could be shown. However, there were considerably higher antibody titers by the IFAT than by FAMA. Whereas the FAMA test had a detection limit of 250 mIU/ml anti-VZV IgG, the limit of detection of IFAT was 50 mIU/ml. In conclusion, the IFAT using VZV-infected A549 cells as antigen allows a highly sensitive, specific, and rapid detection of anti-VZV IgG class antibodies. This simple technique can replace the labor-intensive FAMA procedure for laboratory determination of immunity to VZV.
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Affiliation(s)
- A Sauerbrei
- Institute of Virology and Antiviral Therapy, Friedrich-Schiller University of Jena, Postfach, D-07740 Jena, Germany.
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36
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Al-Mubarak A, Zhou Y, Chowdhury SI. A glycine-rich bovine herpesvirus 5 (BHV-5) gE-specific epitope within the ectodomain is important for BHV-5 neurovirulence. J Virol 2004; 78:4806-16. [PMID: 15078962 PMCID: PMC387723 DOI: 10.1128/jvi.78.9.4806-4816.2004] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The bovine herpesvirus 5 (BHV-5) gE ectodomain contains a glycine-rich epitope coding region (gE5 epitope), residues 204 to 218, that is significantly different from the corresponding gE region of BHV-1. Deletion of the gE epitope significantly reduced the neurovirulence of BHV-5 in rabbits. Pulse-chase analyses revealed that the epitope-deleted and wild-type gE were synthesized as N-glycosylated endoglycosidase H-sensitive precursors with approximate molecular masses of 85 kDa and 86 kDa, respectively. Like the wild-type gE, epitope-deleted gE complexed with gI and was readily transported from the endoplasmic reticulum. Concomitantly, the epitope-deleted and wild-type gE acquired posttranslational modifications in the Golgi leading to an increased apparent molecular mass of 93-kDa (epitope-deleted gE) and 94-kDa (wild-type gE). The kinetics of mutant and wild-type gE processing were similar, and both mature proteins were resistant to endoglycosidase H but sensitive to glycopeptidase F. The gE epitope-deleted BHV-5 formed wild-type-sized plaques in MDBK cells, and the epitope-deleted gE was expressed on the cell surface. However, rabbits infected intranasally with gE epitope-deleted BHV-5 did not develop seizures, and only 20% of the infected rabbits showed mild neurological signs. The epitope-deleted virus replicated efficiently in the olfactory epithelium. However, within the brains of these rabbits there was a 10- to 20-fold reduction in infected neurons compared with the number of infected neurons within the brains of rabbits infected with the gE5 epitope-reverted and wild-type BHV-5. In comparison, 70 to 80% of the rabbits exhibited severe neurological signs when infected with the gE5 epitope-reverted and wild-type BHV-5. These results indicated that anterograde transport of the gE epitope-deleted virus from the olfactory receptor neurons to the olfactory bulb is defective and that, within the central nervous system, the gE5 epitope-coding region was required for expression of the full virulence potential of BHV-5.
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Affiliation(s)
- A Al-Mubarak
- Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, Kansas 66506, USA
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37
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Lin X, Lubinski JM, Friedman HM. Immunization strategies to block the herpes simplex virus type 1 immunoglobulin G Fc receptor. J Virol 2004; 78:2562-71. [PMID: 14963159 PMCID: PMC369259 DOI: 10.1128/jvi.78.5.2562-2571.2004] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Herpes simplex virus type 1 (HSV-1) glycoprotein gE functions as an immunoglobulin G (IgG) Fc receptor (FcgammaR) that promotes immune evasion. When an IgG antibody binds by the F(ab')(2) domain to an HSV antigen, the Fc domain of some of the same antibody molecules binds to the FcgammaR, which blocks Fc-mediated functions. gE is a type 1 membrane glycoprotein with a large ectodomain that is expressed on the virion envelope and infected-cell surface. Our goal was to determine if immunizing with gE protein fragments could produce antibodies that bind by the F(ab')(2) domain to gE and block the FcgammaR, as measured by competitively inhibiting nonimmune human IgG binding to the FcgammaR. Three gE peptides were constructed in baculovirus spanning almost the entire ectodomain and used to immunize mice and rabbits. Two fragments were highly effective at producing antibodies that bind by the F(ab')(2) domain and block the FcgammaR. The most potent of these two antibodies was far more effective at blocking the FcgammaR than antibodies that are only capable of binding by the Fc domains to the FcgammaR, including anti-gC, anti-gD, and nonimmune IgG. These results suggest that immunizing with gE fragments has potential for preventing immune evasion by blocking activities mediated by the HSV-1 FcgammaR.
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Affiliation(s)
- Xiaoqing Lin
- Department of Medicine, Division of Infectious Diseases, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA
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38
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Viau M, Cholley B, Björck L, Zouali M. Down-modulation of the antigen receptor by a superantigen for human B cells. Immunol Lett 2004; 92:91-6. [PMID: 15081532 DOI: 10.1016/j.imlet.2003.10.016] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2003] [Accepted: 10/24/2003] [Indexed: 11/16/2022]
Abstract
B cell superantigens (SAgs) have been implicated in human diseases by demonstrating non-clonotypic expansion of B cells bearing certain immunoglobulin variable region genes. One possibility is that, during infection with microorganisms secreting SAgs, these potent molecules might modulate BcR expression. To test this hypothesis, we investigated the potential effects of a SAg, protein L from Peptostreptococcus magnus, on antigen B cell receptor (BcR) surface expression in vitro. Using fluorescence microscopy, we found that this SAg induced down-regulation of BcR expression. This effect was time-, dose-, and temperature-dependent, and shedding of cell surface IgM molecules into the culture supernatant was not detected. These data demonstrate that SAg-mediated down-regulation of the BcR expression occurs primarily as a result of BcR internalization. In addition, two specific inhibitors of protein tyrosine kinases were found to retard the BcR modulation on the cell surface and inhibit SAg-induced receptor internalization, showing that tyrosine phosphorylation is required for subsequent internalization of mIg-ligand complexes. The down-modulation of BcR expression may have pathological consequences in patients infected with microorganisms secreting SAgs.
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Affiliation(s)
- Muriel Viau
- Institut National de Santé et de Recherche Médicale, Immunopathologie Humaine, 15 rue de l'Ecole de Médecine, 75006 Paris, France
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Sprague ER, Martin WL, Bjorkman PJ. pH dependence and stoichiometry of binding to the Fc region of IgG by the herpes simplex virus Fc receptor gE-gI. J Biol Chem 2004; 279:14184-93. [PMID: 14734541 DOI: 10.1074/jbc.m313281200] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Herpes simplex virus type 1 encodes two glycoproteins, gE and gI, that form a heterodimer on the surface of virions and infected cells. The gE-gI heterodimer has been implicated in cell-to-cell spread of virus and is a receptor for the Fc fragment of IgG. Previous studies localized the gE-gI-binding site on human IgG to a region near the interface between the C(H)2 and C(H)3 domains of Fc, which also serves as the binding site for bacterial and mammalian Fc receptors. Although there are two potential gE-gI-binding sites per Fc homodimer, only one gE-gI heterodimer binds per IgG in gel filtration experiments. Here we report production of recombinant human Fc molecules that contain zero, one, or two potential gE-gI-binding sites and use them in analytical ultracentrifugation experiments to show that two gE-gI heterodimers can bind to each Fc. Further characterization of the gE-gI interaction with Fc reveals a sharp pH dependence of binding, with K(D) values of approximately 340 and approximately 930 nm for the first and second binding events, respectively, at the slightly basic pH of the cell surface (pH 7.4), but undetectable binding at pH 6.0. This strongly pH-dependent interaction suggests a physiological role for gE-gI dissociation from IgG within acidic intracellular compartments, consistent with a mechanism whereby herpes simplex virus promotes intracellular degradation of anti-viral antibodies.
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Affiliation(s)
- Elizabeth R Sprague
- Division of Biology, Howard Hughes Medical Institute, California Institute of Technology, Pasadena, California 91125, USA
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40
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Affiliation(s)
- Roald Nezlin
- Department of Immunology, Weizmann Institute of Science, Rehovot 76100, Israel
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41
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Cole NL, Grose C. Membrane fusion mediated by herpesvirus glycoproteins: the paradigm of varicella-zoster virus. Rev Med Virol 2003; 13:207-22. [PMID: 12820183 DOI: 10.1002/rmv.377] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Varicella-zoster virus (VZV) is well known for its propensity to cause polykaryons (syncytia) in the vesicles within infected skin. Similarly in cultured cells, VZV induces extensive syncytial formation by virus-mediated cell-to-cell fusion. Statistical analyses of fusion parameters demonstrated three-way interactive effects among all three tested variables (incubation temperature, cell type and virus strain). For example, fusion was greatly enhanced at 33 degrees C vs 37 degrees C; also fusion was pronounced in epidermal cells but negligible in fibroblast cells. As with all herpesviruses, VZV gH was a major fusogen. VZV cell fusion was inhibited by antibody to gH, but surprisingly was enhanced by antibody to gE. Other evidence implicating a role for VZV gE in the fusion process was provided by two mutant viruses, in which gE cell surface expression was enhanced. Under transfection conditions, VZV fusion formation occurred after expression of the gH/gL complex; in contrast, pseudorabies virus requires expression of gH, gL and gB, while the herpes simplex virus (HSV) types 1 and 2 require the quartet of gH, gL, gB and gD. VZV has no gD gene and no apparent gD functional homologue. On the other hand, VZV gE exerts a greater effect than HSV gE on membrane fusion. Taken together, the data in this review suggest that VZV has evolved viral glycoprotein machinery more geared toward cell-to-cell fusion (fusion-from-within) than toward virus-to-cell fusion (entry/fusion-from-without), as a means for syncytium formation within the human epidermis.
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Affiliation(s)
- Nancy L Cole
- Departments of Microbiology and Pediatrics, University of Iowa, Iowa City, Iowa, USA
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42
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Rahaus M, Wolff MH. Analyses of the transcriptional pattern of glycoproteins E and I of Varicella-zoster virus and evidence for a monocistronic transcription. J Med Virol 2003; 70 Suppl 1:S51-5. [PMID: 12627488 DOI: 10.1002/jmv.10321] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Glycoproteins I and E of the Varicella-zoster virus, encoded by the neighbouring open reading frames 67 and 68, are transcribed into several transcript species that differ in size. From gI, three transcripts of 1.65, 2.7, and 3.6 kb are known, and from gE, two transcripts of 2.15 and 3.6 kb in size are known. Here, we demonstrate that these various transcript species appear in different amounts at different times post infection. At 12 hr post infection, the transcripts of 1.65 (gI) and 2.15 (gE) were clearly detectable, whereas the other transcripts appeared later on. RT-PCR studies using a set of different primers provided clear evidence that gI and gE are transcribed both, mono- and bicistronically, with predominance on the respective monocistronic transcript. Additional evidence for monocistronic transcription was found in the fact that both glycoproteins contain their own transcriptional start sites. Both promoter regions have their own basal transcription activity and include active TATA-boxes that were recognized by the TATA-box binding protein.
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Affiliation(s)
- Markus Rahaus
- Institute of Microbiology and Virology, University of Witten/Herdecke, Stockumer Strasse 10, D-58448 Witten, Germany
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Van de Walle GR, Favoreel HW, Nauwynck HJ, Pensaert MB. Antibody-induced internalization of viral glycoproteins and gE-gI Fc receptor activity protect pseudorabies virus-infected monocytes from efficient complement-mediated lysis. J Gen Virol 2003; 84:939-947. [PMID: 12655095 DOI: 10.1099/vir.0.18663-0] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Pseudorabies virus (PRV)-infected blood monocytes are able to transport virus throughout the body of vaccination-immune pigs. PRV-infected monocytes express viral glycoproteins in their plasma membrane that can be recognized by virus-specific antibodies. Recently, it has been shown that addition of PRV-specific polyclonal immunoglobulins to PRV-infected monocytes at 37 degrees C induces internalization of the majority of plasma membrane-expressed viral glycoproteins. This study investigated whether this process may interfere with efficient antibody-dependent complement-mediated lysis (ADCML) of infected monocytes. Therefore, an ADCML assay was set up in vitro. A significant decrease in the percentage of cells lysed by ADCML was observed when antibody-induced internalization of PRV glycoproteins occurred (P<0.005). Furthermore, it is shown (i) that the PRV gE-gI complex, which, like certain other alpha herpesvirus orthologues, possesses IgG-binding capacity, aids in avoiding efficient ADCML of PRV-infected monocytes and (ii) that the efficiency of PRV gE-gI-mediated evasion of ADCML can be decreased by the presence of gE-gI-specific antibodies.
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Affiliation(s)
- Gerlinde R Van de Walle
- Laboratory of Virology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, B-9820 Merelbeke, Belgium
| | - Herman W Favoreel
- Laboratory of Virology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, B-9820 Merelbeke, Belgium
| | - Hans J Nauwynck
- Laboratory of Virology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, B-9820 Merelbeke, Belgium
| | - Maurice B Pensaert
- Laboratory of Virology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, B-9820 Merelbeke, Belgium
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Rizvi SM, Raghavan M. Responses of herpes simplex virus type 1-infected cells to the presence of extracellular antibodies: gE-dependent glycoprotein capping and enhancement in cell-to-cell spread. J Virol 2003; 77:701-8. [PMID: 12477873 PMCID: PMC140612 DOI: 10.1128/jvi.77.1.701-708.2003] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Binding of anti-herpes simplex virus (HSV) immunoglobulin G (IgG) to HSV type 1 (HSV-1)-infected HEL and HEp-2 cells causes changes in surface viral glycoprotein distribution, resulting in a capping of all viral glycoproteins towards one pole of the cell. This occurs in a gE-dependent manner. In HEL cells, low concentrations of anti-HSV IgG also enhance cell-to-cell spread of wild-type HSV-1 but not of gE deletion mutant HSV-1. These observations raised the possibility that gE-dependent mechanisms exist that allow some HSV-1-infected cells to respond to the presence of extracellular antibodies by enhancing the antibody-resistant mode of virus transmission.
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Affiliation(s)
- Syed Monem Rizvi
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor 48109-0620, USA
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45
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van der Meulen KM, Nauwynck HJ, Pensaert MB. Absence of viral antigens on the surface of equine herpesvirus-1-infected peripheral blood mononuclear cells: a strategy to avoid complement-mediated lysis. J Gen Virol 2003; 84:93-97. [PMID: 12533704 DOI: 10.1099/vir.0.18864-0] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Equine herpesvirus-1 (EHV-1) may cause abortion in vaccination- and infection-immune horses. EHV-1-infected peripheral blood mononuclear cells (PBMCs) play an important role in virus immune evasion. The mechanisms by which infected PBMCs can avoid destruction by EHV-1-specific antibody and equine complement were examined. The majority of EHV-1-infected PBMCs (68.6 %) lacked surface expression of viral antigens and these cells were not susceptible to complement-mediated lysis. In infected PBMCs with surface expression of viral antigens, 63 % showed focal surface expression, whereas 37 % showed general surface expression. General surface expression rendered infected PBMCs susceptible to lysis by antibody and complement (from 5.4 to 31.2 % lysed cells depending on the concentration of antibody and complement). Infected PBMCs with focal surface expression showed significant lysis only in the presence of high concentrations of antibody and complement. Thus, the absence of surface expression protects infected PBMCs against complement-mediated lysis.
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Affiliation(s)
- Karen M van der Meulen
- Laboratory of Virology, Faculty of Veterinary Medicine, Ghent UniversitySalisburylaan 133, 9820 Merelbeke, Belgium
| | - Hans J Nauwynck
- Laboratory of Virology, Faculty of Veterinary Medicine, Ghent UniversitySalisburylaan 133, 9820 Merelbeke, Belgium
| | - Maurice B Pensaert
- Laboratory of Virology, Faculty of Veterinary Medicine, Ghent UniversitySalisburylaan 133, 9820 Merelbeke, Belgium
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46
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Favoreel HW, Van de Walle GR, Nauwynck HJ, Pensaert MB. Virus complement evasion strategies. J Gen Virol 2003; 84:1-15. [PMID: 12533696 DOI: 10.1099/vir.0.18709-0] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The immune system has a variety of tools at its disposal to combat virus infections. These can be subdivided roughly into two categories: 'first line defence', consisting of the non-specific, innate immune system, and 'adaptive immune response', acquired over time following virus infection or vaccination. During evolution, viruses have developed numerous, and often very ingenious, strategies to counteract efficient recognition of virions or virus-infected cells by both innate and adaptive immunity. This review will focus on the different strategies that viruses use to avoid recognition by one of the components of the immune system: the complement system. Complement evasion is of particular importance for viruses, since complement activation is a crucial component of innate immunity (alternative and mannan-binding lectin activation pathway) as well as of adaptive immunity (classical, antibody-dependent complement activation).
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Affiliation(s)
- Herman W Favoreel
- Laboratory of Virology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, B-9820 Merelbeke, Belgium
| | - Gerlinde R Van de Walle
- Laboratory of Virology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, B-9820 Merelbeke, Belgium
| | - Hans J Nauwynck
- Laboratory of Virology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, B-9820 Merelbeke, Belgium
| | - Maurice B Pensaert
- Laboratory of Virology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, B-9820 Merelbeke, Belgium
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47
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Lubinski JM, Jiang M, Hook L, Chang Y, Sarver C, Mastellos D, Lambris JD, Cohen GH, Eisenberg RJ, Friedman HM. Herpes simplex virus type 1 evades the effects of antibody and complement in vivo. J Virol 2002; 76:9232-41. [PMID: 12186907 PMCID: PMC136467 DOI: 10.1128/jvi.76.18.9232-9241.2002] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Herpes simplex virus type 1 (HSV-1) encodes a complement-interacting glycoprotein, gC, and an immunoglobulin G (IgG) Fc binding glycoprotein, gE, that mediate immune evasion by affecting multiple aspects of innate and acquired immunity, including interfering with complement components C1q, C3, C5, and properdin and blocking antibody-dependent cellular cytotoxicity. Previous studies evaluated the individual contributions of gC and gE to immune evasion. Experiments in a murine model that examines the combined effects of gC and gE immune evasion on pathogenesis are now reported. Virulence of wild-type HSV-1 is compared with mutant viruses defective in gC-mediated C3 binding, gE-mediated IgG Fc binding, or both immune evasion activities. Eliminating both activities greatly increased susceptibility of HSV-1 to antibody and complement neutralization in vitro and markedly reduced virulence in vivo as measured by disease scores, virus titers, and mortality. Studies with C3 knockout mice indicated that other activities attributed to these glycoproteins, such as gC-mediated virus attachment to heparan sulfate or gE-mediated cell-to-cell spread, do not account for the reduced virulence of mutant viruses. The results support the importance of gC and gE immune evasion in vivo and suggest potential new targets for prevention and treatment of HSV disease.
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Affiliation(s)
- John M Lubinski
- Department of Medicine, Division of Infectious Diseases, School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
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48
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Schumacher D, Tischer BK, Reddy SM, Osterrieder N. Glycoproteins E and I of Marek's disease virus serotype 1 are essential for virus growth in cultured cells. J Virol 2001; 75:11307-18. [PMID: 11689611 PMCID: PMC114716 DOI: 10.1128/jvi.75.23.11307-11318.2001] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2001] [Accepted: 08/10/2001] [Indexed: 11/20/2022] Open
Abstract
The role of glycoprotein E (gE) and gI of Marek's disease virus serotype 1 (MDV-1) for growth in cultured cells was investigated. MDV-1 mutants lacking either gE (20DeltagE), gI (20DeltagI), or both gE and gI (20DeltagEI) were constructed by recE/T-mediated mutagenesis of a recently established infectious bacterial artificial chromosome (BAC) clone of MDV-1 (D. Schumacher, B. K. Tischer, W. Fuchs, and N. Osterrieder, J. Virol. 74:11088-11098, 2000). Deletion of either gE or gI, which form a complex in MDV-1-infected cells, resulted in the production of virus progeny that were unable to spread from cell to cell in either chicken embryo fibroblasts or quail muscle cells. This was reflected by the absence of virus plaques and the detection of only single infected cells after transfection, even after coseeding of transfected cells with uninfected cells. In contrast, growth of rescuant viruses, in which the deleted glycoprotein genes were reinserted by homologous recombination, was indistinguishable from that of parental BAC20 virus. In addition, the 20DeltagE mutant virus was able to spread from cell to cell when cotransfected into chicken embryo fibroblasts with an expression plasmid encoding MDV-1 gE, and the 20DeltagI mutant virus exhibited cell-to-cell spread capability after cotransfection with a gI expression plasmid. The 20DeltagEI mutant virus, however, was not able to spread in the presence of either a gE or gI expression plasmid, and only single infected cells were detected by indirect immunofluorescence. The results reported here demonstrate for the first time that both gE and gI are absolutely essential for cell-to-cell spread of a member of the Alphaherpesvirinae.
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Affiliation(s)
- D Schumacher
- Institute of Molecular Biology, Friedrich-Loeffler-Institutes, Federal Research Centre for Virus Diseases of Animals, D-17498 Insel Riems, Germany
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Abstract
Simian varicella virus (SVV) is closely related to human varicella-zoster virus (VZV) and induces a varicella-like disease in nonhuman primates. The SVV genome encodes a glycoprotein E (gE) which is homologous to the gE of VZV and other alphaherpesviruses. The SVV gE was expressed in Escherichia coli and rabbits were immunized with the recombinant gE fusion proteins to generate polyclonal gE antiserum. Immunofluorescence and immunoprecipitation analyses demonstrated that the SVV gE is expressed on the surface and within SVV-infected cells. The gE is also expressed on SVV virions as indicated by serum neutralization assay. The mature SVV gE is glycosylated and is similar in size ( approximately 100 kd) to the mature VZV gE. Immunohistochemical analysis detected gE within skin vesicles and lung tissue of SVV-infected monkeys. Analysis of the humoral immune response to gE in an SVV-infected monkey determined that anti-gE antibody is induced as early as day 9 postinfection and persists at high titer for longer than 4 months. The simian varicella model offers an opportunity to investigate the role of gE in viral pathogenesis and immunity and to evaluate its potential as a varicella vaccine.
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Affiliation(s)
- W L Gray
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, 4301 West Markham Street, Slot 511, Little Rock, AR 72205, USA.
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50
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Antonsson A, Johansson PJH. Binding of human and animal immunoglobulins to the IgG Fc receptor induced by human cytomegalovirus. J Gen Virol 2001; 82:1137-1145. [PMID: 11297688 DOI: 10.1099/0022-1317-82-5-1137] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Human cytomegalovirus (HCMV)-infected cells express a virus-encoded receptor that is able to bind the Fc part of IGG: Some basic binding properties of this Fc receptor (FcR) have been examined. The affinity constant (K(a)) for human IgG Fc fragment in its interaction with acetone-fixed, HCMV-infected human embryonic lung fibroblasts was estimated to be around 2 x 10(8) M(-1) and the number of binding sites was estimated to be around 2 x 10(6) per cell. Of the human IgG, IgA, IgM and IgD classes, only IgG reacted with the receptor, and all four of the IgG subclasses were reactive. IgG from rabbit, hamster, cat, swine and horse exhibited binding to the HCMV FcR, in contrast to IgG from mouse, rat, guinea pig, dog, sheep, goat, cow and chicken. Immunoglobulins with and without HCMV IgG FcR-binding properties, like IgG from rabbit and mouse, can be of value in revealing the functional importance of the receptor. When the immunoglobulins were tested against herpes simplex virus type 1-induced FcR, both similarities and differences in immunoreactivity were seen relative to the HCMV FcR, which makes it unlikely that the binding sites for these two herpesvirus FcRs on the IgG molecule are identical.
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Affiliation(s)
- Annika Antonsson
- Section of Virology, Department of Infectious Diseases and Medical Microbiology, University of Lund, Sölvegatan 23, S-221 85 Lund, Sweden1
| | - P J Hugo Johansson
- Section of Virology, Department of Infectious Diseases and Medical Microbiology, University of Lund, Sölvegatan 23, S-221 85 Lund, Sweden1
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