1
|
Zeng C, Qiao M, Chen Y, Xie H. EBV-positive glycoproteins associated with nasopharyngeal carcinoma. Pathol Res Pract 2024; 260:155427. [PMID: 38936091 DOI: 10.1016/j.prp.2024.155427] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/04/2023] [Revised: 06/15/2024] [Accepted: 06/20/2024] [Indexed: 06/29/2024]
Abstract
Nasopharyngeal carcinoma (NPC) is closely related to Epstein-Barr virus (EBV) infection, and glycosylation of proteins is associated with precancerous lesions and carcinogenesis of NPC, and viral glycoproteins mediates the fusion of viruses with B cells or epithelial cells in the infection stage, promoting the conversion of normal epithelial cells into cancer cells. In the process of occurrence and development of NPC, various glycoproteins in the body promote or inhibit the proliferation, invasion, metastasis, and drug resistance of tumor cells, such as the tumor inhibitory effect of NGX6 and inhibin B (INHBB); the cancer-promoting effect of tenascin-C (TNC), fibronectin 1 (FN1), insulin-like growth factor binding protein-3 (IGFBP3), serglycin, and its core protein; and some effects of glycosylation of immune proteins on immunotherapy in NPC. This article provides an overview of the research progress on the interaction of glycoproteins associated with EBV infection with the occurrence and development of NPC.
Collapse
Affiliation(s)
- Chenlu Zeng
- Key Laboratory of Cancer Cellular and Molecular Pathology in Hunan Province, Cancer Research Institute of Hengyang Medical College, University of South China, Hengyang, Hunan Province 421001, China
| | - Muchuan Qiao
- Key Laboratory of Cancer Cellular and Molecular Pathology in Hunan Province, Cancer Research Institute of Hengyang Medical College, University of South China, Hengyang, Hunan Province 421001, China
| | - Yanhua Chen
- Department of Medical Oncology, the Second Affiliated Hospital of the University of South China, Hengyang, Hunan Province, China
| | - Hailong Xie
- Key Laboratory of Cancer Cellular and Molecular Pathology in Hunan Province, Cancer Research Institute of Hengyang Medical College, University of South China, Hengyang, Hunan Province 421001, China.
| |
Collapse
|
2
|
A Neutralizing Antibody Targeting gH Provides Potent Protection against EBV Challenge In Vivo. J Virol 2022; 96:e0007522. [PMID: 35348362 DOI: 10.1128/jvi.00075-22] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Epstein-Barr virus (EBV) is an oncogenic herpesvirus that is associated with 200,000 new cases of cancer and 140,000 deaths annually. To date, there are no available vaccines or therapeutics for clinical usage. Recently, the viral heterodimer glycoprotein gH/gL has become a promising target for the development of prophylactic vaccines against EBV. Here, we developed the anti-gH antibody 6H2 and its chimeric version C6H2, which had full neutralizing activity in epithelial cells and partial neutralizing activity in B cells. C6H2 exhibited potent protection against lethal EBV challenge in a humanized mouse model. The cryo-electron microscopy (cryo-EM) structure further revealed that 6H2 recognized a previously unidentified epitope on gH/gL D-IV that is critical for viral attachment and subsequent membrane fusion with epithelial cells. Our results suggest that C6H2 is a promising candidate in the prevention of EBV-induced lymphoproliferative diseases (LPDs) and may inform the design of an EBV vaccine. IMPORTANCE Epstein-Barr virus (EBV) is a ubiquitous gammaherpesvirus that establishes lifelong persistence and is related to multiple diseases, including cancers. Neutralizing antibodies (NAbs) have proven to be highly effective in preventing EBV infection and subsequent diseases. Here, we developed an anti-EBV-gH NAb, 6H2, which blocked EBV infection in vitro and in vivo. This 6H2 neutralizing epitope should be helpful to understand EBV infection mechanisms and guide the development of vaccines and therapeutics against EBV infection.
Collapse
|
3
|
Zhu QY, Shan S, Yu J, Peng SY, Sun C, Zuo Y, Zhong LY, Yan SM, Zhang X, Yang Z, Peng YJ, Shi X, Cao SM, Wang X, Zeng MS, Zhang L. A potent and protective human neutralizing antibody targeting a novel vulnerable site of Epstein-Barr virus. Nat Commun 2021; 12:6624. [PMID: 34785638 PMCID: PMC8595662 DOI: 10.1038/s41467-021-26912-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Accepted: 10/26/2021] [Indexed: 12/13/2022] Open
Abstract
Epstein-Barr virus (EBV) is associated with a range of epithelial and B cell malignancies as well as autoimmune disorders, for which there are still no specific treatments or effective vaccines. Here, we isolate EBV gH/gL-specific antibodies from an EBV-infected individual. One antibody, 1D8, efficiently neutralizes EBV infection of two major target cell types, B cells and epithelial cells. In humanized mice, 1D8 provides protection against a high-dose EBV challenge by substantially reducing viral loads and associated tumor burden. Crystal structure analysis reveals that 1D8 binds to a key vulnerable interface between the D-I/D-II domains of the viral gH/gL protein, especially the D-II of the gH, thereby interfering with the gH/gL-mediated membrane fusion and binding to target cells. Overall, we identify a potent and protective neutralizing antibody capable of reducing the EBV load. The novel vulnerable site represents an attractive target that is potentially important for antibody and vaccine intervention against EBV infection.
Collapse
Affiliation(s)
- Qian-Ying Zhu
- grid.488530.20000 0004 1803 6191State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and Therapy, Sun Yat-sen University Cancer Center (SYSUCC), 510060 Guangzhou, China ,grid.12981.330000 0001 2360 039XDepartment of Laboratory Medicine, The Eighth Affiliated Hospital, Sun Yat-sen University, Shenzhen, 518003 PR China
| | - Sisi Shan
- grid.12527.330000 0001 0662 3178NexVac Research Center, Comprehensive AIDS Research Center, Center for Infectious Diseases Research, Beijing Advanced Innovation Center for Structural Biology, School of Medicine, Tsinghua University, 100084 Beijing, China
| | - Jinfang Yu
- grid.12527.330000 0001 0662 3178The Ministry of Education Key Laboratory of Protein Science, Beijing Advanced Innovation Center for Structural Biology, Beijing Frontier Research Center for Biological Structure, Collaborative Innovation Center for Biotherapy, School of Life Sciences, Tsinghua University, 100084 Beijing, China
| | | | - Cong Sun
- grid.488530.20000 0004 1803 6191State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and Therapy, Sun Yat-sen University Cancer Center (SYSUCC), 510060 Guangzhou, China
| | - Yanan Zuo
- grid.12527.330000 0001 0662 3178NexVac Research Center, Comprehensive AIDS Research Center, Center for Infectious Diseases Research, Beijing Advanced Innovation Center for Structural Biology, School of Medicine, Tsinghua University, 100084 Beijing, China
| | - Lan-Yi Zhong
- grid.488530.20000 0004 1803 6191State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and Therapy, Sun Yat-sen University Cancer Center (SYSUCC), 510060 Guangzhou, China
| | - Shu-Mei Yan
- grid.488530.20000 0004 1803 6191State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and Therapy, Sun Yat-sen University Cancer Center (SYSUCC), 510060 Guangzhou, China
| | - Xiao Zhang
- grid.488530.20000 0004 1803 6191State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and Therapy, Sun Yat-sen University Cancer Center (SYSUCC), 510060 Guangzhou, China
| | - Ziqing Yang
- grid.12527.330000 0001 0662 3178NexVac Research Center, Comprehensive AIDS Research Center, Center for Infectious Diseases Research, Beijing Advanced Innovation Center for Structural Biology, School of Medicine, Tsinghua University, 100084 Beijing, China
| | - Yong-Jian Peng
- grid.488530.20000 0004 1803 6191State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and Therapy, Sun Yat-sen University Cancer Center (SYSUCC), 510060 Guangzhou, China
| | - Xuanling Shi
- grid.12527.330000 0001 0662 3178NexVac Research Center, Comprehensive AIDS Research Center, Center for Infectious Diseases Research, Beijing Advanced Innovation Center for Structural Biology, School of Medicine, Tsinghua University, 100084 Beijing, China
| | - Su-Mei Cao
- grid.488530.20000 0004 1803 6191State Key Laboratory of Oncology in South China, Department of Cancer Prevention Research, Sun Yat-sen University Cancer Center (SYSUCC), 510060 Guangzhou, China
| | - Xinquan Wang
- The Ministry of Education Key Laboratory of Protein Science, Beijing Advanced Innovation Center for Structural Biology, Beijing Frontier Research Center for Biological Structure, Collaborative Innovation Center for Biotherapy, School of Life Sciences, Tsinghua University, 100084, Beijing, China.
| | - Mu-Sheng Zeng
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and Therapy, Sun Yat-sen University Cancer Center (SYSUCC), 510060, Guangzhou, China.
| | - Linqi Zhang
- NexVac Research Center, Comprehensive AIDS Research Center, Center for Infectious Diseases Research, Beijing Advanced Innovation Center for Structural Biology, School of Medicine, Tsinghua University, 100084, Beijing, China. .,Institute of Biopharmaceutical and Health Engineering, Tsinghua Shenzhen International Graduate School, Tsinghua University, 518055, Shenzhen, China. .,Institute of Biomedical Health Technology and Engineering, Shenzhen Bay Laboratory, 518132, Shenzhen, China.
| |
Collapse
|
4
|
Zhu QY, Zhao GX, Li Y, Talakatta G, Mai HQ, Le QT, Young LS, Zeng MS. Advances in pathogenesis and precision medicine for nasopharyngeal carcinoma. MedComm (Beijing) 2021; 2:175-206. [PMID: 34766141 PMCID: PMC8491203 DOI: 10.1002/mco2.32] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Revised: 07/28/2020] [Accepted: 07/29/2020] [Indexed: 12/13/2022] Open
Abstract
Nasopharyngeal carcinoma (NPC) is a squamous carcinoma with apparent geographical and racial distribution, mostly prevalent in East and Southeast Asia, particularly concentrated in southern China. The epidemiological trend over the past decades has suggested a substantial reduction in the incidence rate and mortality rate due to NPC. These results may reflect changes in lifestyle and environment, and more importantly, a deeper comprehension of the pathogenic mechanism of NPC, leading to much progress in the preventing, screening, and treating for this cancer. Herein, we present the recent advances on the key signal pathways involved in pathogenesis of NPC, the mechanism of Epstein‐Barr virus (EBV) entry into the cell, and the progress of EBV vaccine and screening biomarkers. We will also discuss in depth the development of various therapeutic approaches including radiotherapy, chemotherapy, surgery, targeted therapy, and immunotherapy. These research advancements have led to a new era of precision medicine in NPC.
Collapse
Affiliation(s)
- Qian-Ying Zhu
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and Therapy Sun Yat-sen University Cancer Center (SYSUCC) Guangzhou China
| | - Ge-Xin Zhao
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and Therapy Sun Yat-sen University Cancer Center (SYSUCC) Guangzhou China
| | - Yan Li
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and Therapy Sun Yat-sen University Cancer Center (SYSUCC) Guangzhou China
| | - Girish Talakatta
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and Therapy Sun Yat-sen University Cancer Center (SYSUCC) Guangzhou China
| | - Hai-Qiang Mai
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and Therapy Sun Yat-sen University Cancer Center (SYSUCC) Guangzhou China
| | - Quynh-Thu Le
- Department of Radiation Oncology Stanford California
| | - Lawrence S Young
- Warwick Medical School University of Warwick Coventry United Kingdom
| | - Mu-Sheng Zeng
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and Therapy Sun Yat-sen University Cancer Center (SYSUCC) Guangzhou China
| |
Collapse
|
5
|
A conditionally replication-defective cytomegalovirus vaccine elicits potent and diverse functional monoclonal antibodies in a phase I clinical trial. NPJ Vaccines 2021; 6:79. [PMID: 34078915 PMCID: PMC8172929 DOI: 10.1038/s41541-021-00342-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Accepted: 04/24/2021] [Indexed: 02/03/2023] Open
Abstract
A conditionally replication-defective human cytomegalovirus (HCMV) vaccine, V160, was shown to be safe and immunogenic in a two-part, double-blind, randomized, placebo-controlled phase I clinical trial (NCT01986010). However, the specificities and functional properties of V160-elicited antibodies remain undefined. Here, we characterized 272 monoclonal antibodies (mAbs) isolated from single memory B cells of six V160-vaccinated subjects. The mAbs bind to diverse HCMV antigens, including multiple components of the pentamer, gB, and tegument proteins. The most-potent neutralizing antibodies target the pentamer-UL subunits. The binding sites of the antibodies overlap with those of antibodies responding to natural HCMV infection. The majority of the neutralizing antibodies target the gHgL subunit. The non-neutralizing antibodies predominantly target the gB and pp65 proteins. Sequence analysis indicated that V160 induced a class of gHgL antibodies expressing the HV1-18/KV1-5 germline genes in multiple subjects. This study provides valuable insights into primary targets for anti-HCMV antibodies induced by V160 vaccination.
Collapse
|
6
|
Jakhmola S, Hazarika Z, Jha AN, Jha HC. In silico analysis of antiviral phytochemicals efficacy against Epstein-Barr virus glycoprotein H. J Biomol Struct Dyn 2021; 40:5372-5385. [PMID: 33438528 DOI: 10.1080/07391102.2020.1871074] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Epstein-Barr virus is a tumor-associated, enveloped virus with glycoprotein receptor gHgL on its surface. gH attaches to epithelial or B cells and mediates internalization. Till date, no specific anti-EBV FDA approved drug is available. Targeting gH may aid in designing virus-specific therapeutics and reducing the drug induced complications in host. We investigated the influence of antiviral phytochemicals on gH using computational approaches. Through molecular docking, we performed binding energy analysis of cellocidin, bruceantin, EGCG, formononetin and sesquiterpene lactones with gH DII/DIII interface, crucial for gH functions. Further, to cause any perturbations in the protein function, the molecules must bind stably to gH. Bruceantin and EGCG interacted with high affinities to gH. Simulation of these two molecules revealed stable binding with gH throughout 100 ns moreover, van der Waal interactions stabilized overall binding. Mutation of amino acids like V265, L269, L315, I423, I459, L474 and F475 involved in stable binding to gH was predicted deleterious to protein function. We obtained no difference in RMSD between these two ligands and minor deviations in the RMSF were noticed compared to gH. Conclusively, our study provided insights into the potential of bruceantin and EGCG to target gH. Different amino acids are involved in binding of each ligand to gH, engagement of certain amino acids may affect the virus binding with epithelial or B cells. The interaction of the ligand with gH may trap it in its native conformation or induce structural flexibility thereby inhibiting the interaction with host receptors or other glycoproteins.Communicated by Ramaswamy H. Sarma.
Collapse
Affiliation(s)
- Shweta Jakhmola
- Discipline of Biosciences and Biomedical Engineering, Indian Institute of Technology Indore, Indore, India
| | - Zaved Hazarika
- Department of Molecular Biology and Biotechnology, Tezpur University, Tezpur, India
| | - Anupam Nath Jha
- Department of Molecular Biology and Biotechnology, Tezpur University, Tezpur, India
| | - Hem Chandra Jha
- Discipline of Biosciences and Biomedical Engineering, Indian Institute of Technology Indore, Indore, India
| |
Collapse
|
7
|
Epstein-Barr Virus gH/gL and Kaposi's Sarcoma-Associated Herpesvirus gH/gL Bind to Different Sites on EphA2 To Trigger Fusion. J Virol 2020; 94:JVI.01454-20. [PMID: 32847853 DOI: 10.1128/jvi.01454-20] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Accepted: 08/18/2020] [Indexed: 12/22/2022] Open
Abstract
Both Epstein-Barr virus (EBV) and Kaposi's sarcoma-associated herpesvirus (KSHV) are human gammaherpesviruses and are important in a variety of malignancies. Eph family receptor tyrosine kinase A2 (EphA2) is a cellular receptor for KSHV and EBV. Previous studies identified five conserved residues (ELEFN50-54) in the N-terminal domain of KSHV gH that are critical for Eph binding and KSHV infection. However, the specific domains of EBV gH/gL important for EphA2 binding are not well described. We found that the KSHV gH (ELEFN50-54) motif is important for higher KSHV fusion and that EBV gH/gL does not utilize a similar motif for fusion activity. We previously identified that an EBV gL N-glycosylation mutant (gL-N69L/S71V) was hyperfusogenic in epithelial cells but not in B cells. To determine whether this glycosylation site may be the binding region for EphA2, we compared the EphA2 binding activity of EBV gH/gL and the EBV gH/gL-N69L/S71V mutant. We found that EBV gH/gL-N69L/S71V had higher binding affinity for EphA2, indicating that the EBV gL N-glycosylation site might be responsible for inhibiting the binding of gH/gL to EphA2. Loss of N-glycosylation at this site may remove steric hindrance that reduces EBV gH/gL binding to EphA2. In addition, the mutations located in the large groove of EBV gH/gL (R152A and G49C) also have decreased binding with EphA2. Taken together, our data indicate that the binding site of EphA2 on EBV gH/gL is at least in part proximal to the EBV gL glycosylation site, which in part accounts for differences in EphA2 binding affinity by KSHV.IMPORTANCE Virus entry into target cells is the first step for virus infection. Understanding the overall entry mechanism, including the binding mechanism of specific virus glycoproteins with cellular receptors, can be useful for the design of small molecule inhibitors and vaccine development. Recently, EphA2 was identified as an important entry receptor for both KSHV and EBV. In the present study, we investigated the required binding sites within EphA2 and EBV gH/gL that mediate the interaction of these two proteins allowing entry into epithelial cells and found that it differed in compared to the interaction of KSHV gH/gL with EphA2. Our discoveries may uncover new potential interventional strategies that block EBV and KSHV infection of target epithelial cells.
Collapse
|
8
|
Chen J, Longnecker R. Epithelial cell infection by Epstein-Barr virus. FEMS Microbiol Rev 2020; 43:674-683. [PMID: 31584659 DOI: 10.1093/femsre/fuz023] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Accepted: 10/02/2019] [Indexed: 12/13/2022] Open
Abstract
Epstein-Barr Virus (EBV) is etiologically associated with multiple human malignancies including Burkitt lymphoma and Hodgkin disease as well as nasopharyngeal and gastric carcinoma. Entry of EBV into target cells is essential for virus to cause disease and is mediated by multiple viral envelope glycoproteins and cell surface associated receptors. The target cells of EBV include B cells and epithelial cells. The nature and mechanism of EBV entry into these cell types are different, requiring different glycoprotein complexes to bind to specific receptors on the target cells. Compared to the B cell entry mechanism, the overall mechanism of EBV entry into epithelial cells is less well known. Numerous receptors have been implicated in this process and may also be involved in additional processes of EBV entry, transport, and replication. This review summarizes EBV glycoproteins, host receptors, signal molecules and transport machinery that are being used in the epithelial cell entry process and also provides a broad view for related herpesvirus entry mechanisms.
Collapse
Affiliation(s)
- Jia Chen
- Department of Microbiology and Immunology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Richard Longnecker
- Department of Microbiology and Immunology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| |
Collapse
|
9
|
Qiao Y, Zhao X, Liu J, Yang W. Epstein-Barr virus circRNAome as host miRNA sponge regulates virus infection, cell cycle, and oncogenesis. Bioengineered 2020; 10:593-603. [PMID: 31668120 PMCID: PMC6844377 DOI: 10.1080/21655979.2019.1679698] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Epstein-Barr virus (EBV) is an oncogenic virus that infects more than 90% of the world’s population. The proteins and miRNAs encoded by EBV are involved in multiple human malignancies. Recently R-resistance RNA-seq demonstrated that EBV-encoded circular RNAs. The current research aims to explore their functions in EBV-associated malignancies. Total 56 miRNAs were sponged by circRNAome. 24 and 9 in EBV host B and epithelial cells out of 56 miRNAs were detectable by miRNA-seq. 18 and 5 miRNAs were down-regulated in both types of host cells, respectively, after EBV infection. The network between five miRNAs and their targets included 1414 genes, 1419 nodes, and 2423 edges. These targets were enriched in multiple categories, and most of them were up-regulated in EBV-infected cells. These data represented the first report that EBV circRNAs could sponge the miRNAs to promote the up-regulated expression of their targets, involving in malignancies associated with EBV.
Collapse
Affiliation(s)
- Yanwei Qiao
- Department of Infectious Disease, Tianjin First Center Hospital, Tianjin, China
| | - Xuequn Zhao
- Department of Infectious Disease, Tianjin First Center Hospital, Tianjin, China
| | - Jun Liu
- Department of Infectious Disease, Tianjin First Center Hospital, Tianjin, China
| | - Wenjie Yang
- Department of Infectious Disease, Tianjin First Center Hospital, Tianjin, China
| |
Collapse
|
10
|
Gammaherpesvirus entry and fusion: A tale how two human pathogenic viruses enter their host cells. Adv Virus Res 2019; 104:313-343. [PMID: 31439152 DOI: 10.1016/bs.aivir.2019.05.006] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The prototypical human γ-herpesviruses Epstein-Barr virus (EBV) and Kaposi Sarcoma-associated herpesvirus (KSHV) are involved in the development of malignancies. Like all herpesviruses, they share the establishment of latency, the typical architecture, and the conserved fusion machinery to initiate infection. The fusion machinery reflects virus-specific adaptations due to the requirements of the respective herpesvirus. For example, EBV evolved a tropism switch involving either the B- or epithelial cell-tropism complexes to activate fusion driven by gB. Most of the EBV entry proteins and their cellular receptors have been crystallized providing molecular details of the initial steps of infection. For KSHV, a variety of entry and binding receptors has also been reported but the mechanism how receptor binding activates gB-driven fusion is not as well understood as that for EBV. However, the downstream signaling pathways that promote the early steps of KSHV entry are well described. This review summarizes the current knowledge of the key players involved in EBV and KSHV entry and the cell-type specific mechanisms that allow infection of a wide variety of cell types.
Collapse
|
11
|
Snijder J, Ortego MS, Weidle C, Stuart AB, Gray MD, McElrath MJ, Pancera M, Veesler D, McGuire AT. An Antibody Targeting the Fusion Machinery Neutralizes Dual-Tropic Infection and Defines a Site of Vulnerability on Epstein-Barr Virus. Immunity 2018; 48:799-811.e9. [PMID: 29669253 PMCID: PMC5909843 DOI: 10.1016/j.immuni.2018.03.026] [Citation(s) in RCA: 87] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Revised: 01/18/2018] [Accepted: 03/23/2018] [Indexed: 01/01/2023]
Abstract
Epstein-Barr virus (EBV) is a causative agent of infectious mononucleosis and is associated with 200,000 new cases of cancer and 140,000 deaths annually. Subunit vaccines against this pathogen have focused on the gp350 glycoprotein and remain unsuccessful. We isolated human antibodies recognizing the EBV fusion machinery (gH/gL and gB) from rare memory B cells. One anti-gH/gL antibody, AMMO1, potently neutralized infection of B cells and epithelial cells, the two major cell types targeted by EBV. We determined a cryo-electron microscopy reconstruction of the gH/gL-gp42-AMMO1 complex and demonstrated that AMMO1 bound to a discontinuous epitope formed by both gH and gL at the Domain-I/Domain-II interface. Integrating structural, biochemical, and infectivity data, we propose that AMMO1 inhibits fusion of the viral and cellular membranes. This work identifies a crucial epitope that may aid in the design of next-generation subunit vaccines against this major public health burden.
Collapse
Affiliation(s)
- Joost Snijder
- Department of Biochemistry, University of Washington, Seattle, WA 98195, USA
| | - Michael S Ortego
- Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, 1100 Fairview Ave. N. PO Box 19024, Seattle, WA 98109, USA
| | - Connor Weidle
- Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, 1100 Fairview Ave. N. PO Box 19024, Seattle, WA 98109, USA
| | - Andrew B Stuart
- Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, 1100 Fairview Ave. N. PO Box 19024, Seattle, WA 98109, USA
| | - Matthew D Gray
- Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, 1100 Fairview Ave. N. PO Box 19024, Seattle, WA 98109, USA
| | - M Juliana McElrath
- Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, 1100 Fairview Ave. N. PO Box 19024, Seattle, WA 98109, USA; Department of Medicine, University of Washington, Seattle, WA 98195, USA
| | - Marie Pancera
- Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, 1100 Fairview Ave. N. PO Box 19024, Seattle, WA 98109, USA
| | - David Veesler
- Department of Biochemistry, University of Washington, Seattle, WA 98195, USA; Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, 1100 Fairview Ave. N. PO Box 19024, Seattle, WA 98109, USA.
| | - Andrew T McGuire
- Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, 1100 Fairview Ave. N. PO Box 19024, Seattle, WA 98109, USA; Department of Global Health, University of Washington, Seattle, WA 98195, USA.
| |
Collapse
|
12
|
Ephrin receptor A2 is a functional entry receptor for Epstein-Barr virus. Nat Microbiol 2018; 3:172-180. [PMID: 29292384 PMCID: PMC5972547 DOI: 10.1038/s41564-017-0081-7] [Citation(s) in RCA: 138] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2017] [Accepted: 11/21/2017] [Indexed: 12/20/2022]
Abstract
Epstein-Barr virus (EBV) is an oncogenic virus that infects more than 90% of the world’s population1. EBV predominantly infects human B cells and epithelial cells, which is initiated by fusion of the viral envelope with a host cellular membrane2. The mechanism of EBV entry into B cells has been well characterized3. However, the mechanism for epithelial cell entry remains elusive. Here, we show that the integrins (αvβ5, αvβ6, and αvβ8) do not function as an entry and fusion receptor for epithelial cells whereas ephrin receptor tyrosine kinase A2 (EphA2) functions well for both. EphA2 overexpression significantly increased EBV infection of HEK 293 cells. Using a virus-free cell-cell fusion assay, we found that EphA2 dramatically promoted EBV but not HSV fusion with HEK293 cells. EphA2 silencing using shRNA or knockout by CRISPR/Cas9 blocked fusion with epithelial cells. This inhibitory effect was rescued by the expression of EphA2. Antibody against EphA2 blocked epithelial cell infection. Using label-free Surface Plasmon Resonance (SPR) binding studies, we confirmed that EphA2 but not EphA4 specifically bound to EBV gHgL and this interaction is through the EphA2 extracellular domain (EphA2-ECD). The discovery of EphA2 as an EBV epithelial cell receptor has important implications for EBV pathogenesis and may uncover new potential targets that can be used for the development of novel interventional strategies.
Collapse
|
13
|
Abstract
Herpesvirus entry into cells requires the coordinated action of multiple virus envelope glycoproteins, including gH, gL, and gB. For EBV, the gp42 protein assembles into complexes with gHgL heterodimers and binds HLA class II to activate gB-mediated membrane fusion with B cells. EBV tropism is dictated by gp42 levels in the virion, as it inhibits entry into epithelial cells while promoting entry into B cells. The gHgL and gB proteins are targets of neutralizing antibodies and potential candidates for subunit vaccine development, but our understanding of their neutralizing epitopes and the mechanisms of inhibition remain relatively unexplored. Here we studied the structures and mechanisms of two anti-gHgL antibodies, CL40 and CL59, that block membrane fusion with both B cells and epithelial cells. We determined the structures of the CL40 and CL59 complexes with gHgL using X-ray crystallography and EM to identify their epitope locations. CL59 binds to the C-terminal domain IV of gH, while CL40 binds to a site occupied by the gp42 receptor binding domain. CL40 binding to gHgL/gp42 complexes is not blocked by gp42 and does not interfere with gp42 binding to HLA class II, indicating that its ability to block membrane fusion with B cells represents a defect in gB activation. These data indicate that anti-gHgL neutralizing antibodies can block gHgL-mediated activation of gB through different surface epitopes and mechanisms.
Collapse
|
14
|
Chandramouli S, Malito E, Nguyen T, Luisi K, Donnarumma D, Xing Y, Norais N, Yu D, Carfi A. Structural basis for potent antibody-mediated neutralization of human cytomegalovirus. Sci Immunol 2017; 2:2/12/eaan1457. [DOI: 10.1126/sciimmunol.aan1457] [Citation(s) in RCA: 68] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Accepted: 05/19/2017] [Indexed: 11/02/2022]
|
15
|
Structural basis for Epstein-Barr virus host cell tropism mediated by gp42 and gHgL entry glycoproteins. Nat Commun 2016; 7:13557. [PMID: 27929061 PMCID: PMC5155155 DOI: 10.1038/ncomms13557] [Citation(s) in RCA: 69] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Accepted: 10/13/2016] [Indexed: 12/12/2022] Open
Abstract
Herpesvirus entry into host cells is mediated by multiple virally encoded receptor binding and membrane fusion glycoproteins. Despite their importance in host cell tropism and associated disease pathology, the underlying and essential interactions between these viral glycoproteins remain poorly understood. For Epstein–Barr virus (EBV), gHgL/gp42 complexes bind HLA class II to activate membrane fusion with B cells, but gp42 inhibits fusion and entry into epithelial cells. To clarify the mechanism by which gp42 controls the cell specificity of EBV infection, here we determined the structure of gHgL/gp42 complex bound to an anti-gHgL antibody (E1D1). The critical regulator of EBV tropism is the gp42 N-terminal domain, which tethers the HLA-binding domain to gHgL by wrapping around the exterior of three gH domains. Both the gp42 N-terminal domain and E1D1 selectively inhibit epithelial-cell fusion; however, they engage distinct surfaces of gHgL. These observations clarify key determinants of EBV host cell tropism.
The entry of herpesviruses (such as Epstein-Barr virus) into host cells is mediated by a multitude of glycoproteins. Here, the authors show the structure of a viral glycoprotein complex, gHgL/gp42, bound to an anti-gHgL antibody, clarifying determinants of EBV host cell tropism.
Collapse
|
16
|
The Cytoplasmic Tail Domain of Epstein-Barr Virus gH Regulates Membrane Fusion Activity through Altering gH Binding to gp42 and Epithelial Cell Attachment. mBio 2016; 7:mBio.01871-16. [PMID: 27935841 PMCID: PMC5111410 DOI: 10.1128/mbio.01871-16] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Epstein-Barr virus (EBV) is associated with infectious mononucleosis and a variety of cancers as well as lymphoproliferative disorders in immunocompromised patients. EBV mediates viral entry into epithelial and B cells using fusion machinery composed of four glycoproteins: gB, the gH/gL complex, and gp42. gB and gH/gL are required for both epithelial and B cell fusion. The specific role of gH/gL in fusion has been the most elusive among the required herpesvirus entry glycoproteins. Previous mutational studies have focused on the ectodomain of EBV gH and not on the gH cytoplasmic tail domain (CTD). In this study, we chose to examine the function of the gH CTD by making serial gH truncation mutants as well as amino acid substitution mutants to determine the importance of the gH CTD in epithelial and B cell fusion. Truncation of 8 amino acids (aa 698 to 706) of the gH CTD resulted in diminished fusion activity using a virus-free syncytium formation assay and fusion assay. The importance of the amino acid composition of the gH CTD was also investigated by amino acid substitutions that altered the hydrophobicity or hydrophilicity of the CTD. These mutations also resulted in diminished fusion activity. Interestingly, some of the gH CTD truncation mutants and hydrophilic tail substitution mutants lost the ability to bind to gp42 and epithelial cells. In summary, our studies indicate that the gH CTD is an important functional domain. Infection with Epstein-Barr virus (EBV) causes diseases ranging from the fairly benign infectious mononucleosis to life-threatening cancer. Entry into target cells is the first step for viral infection and is important for EBV to cause disease. Understanding the EBV entry mechanism is useful for the development of infection inhibitors and developing EBV vaccine approaches. Epithelial and B cells are the main target cells for EBV infection. The essential glycoproteins for EBV entry include gB, gH/gL, and gp42. We characterized the function of the EBV gH C-terminal cytoplasmic tail domain (CTD) in fusion using a panel of gH CTD truncation or substitution mutants. We found that the gH CTD regulates fusion by altering gp42 and epithelial cell attachment. Our studies may lead to a better understanding of EBV fusion and entry, which may result in novel therapies that target the EBV entry step.
Collapse
|
17
|
Oliver SL, Yang E, Arvin AM. Varicella-Zoster Virus Glycoproteins: Entry, Replication, and Pathogenesis. CURRENT CLINICAL MICROBIOLOGY REPORTS 2016; 3:204-215. [PMID: 28367398 DOI: 10.1007/s40588-016-0044-4] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Varicella-zoster virus (VZV), an alphaherpesvirus that causes chicken pox (varicella) and shingles (herpes zoster), is a medically important pathogen that causes considerable morbidity and, on occasion, mortality in immunocompromised patients. Herpes zoster can afflict the elderly with a debilitating condition, postherpetic neuralgia, triggering severe, untreatable pain for months or years. The lipid envelope of VZV, similar to all herpesviruses, contains numerous glycoproteins required for replication and pathogenesis. PURPOSE OF REVIEW To summarize the current knowledge about VZV glycoproteins and their roles in cell entry, replication and pathogenesis. RECENT FINDINGS The functions for some VZV glycoproteins are known, such as gB, gH and gL in membrane fusion, cell-cell fusion regulation, and receptor binding properties. However, the molecular mechanisms that trigger or mediate VZV glycoproteins remains poorly understood. SUMMARY VZV glycoproteins are central to successful replication but their modus operandi during replication and pathogenesis remain elusive requiring further mechanistic based studies.
Collapse
Affiliation(s)
- Stefan L Oliver
- Departments of Pediatrics and Microbiology & Immunology, Stanford University School of Medicine, Stanford, California, 94305-5208
| | - Edward Yang
- Departments of Pediatrics and Microbiology & Immunology, Stanford University School of Medicine, Stanford, California, 94305-5208
| | - Ann M Arvin
- Departments of Pediatrics and Microbiology & Immunology, Stanford University School of Medicine, Stanford, California, 94305-5208
| |
Collapse
|
18
|
Campadelli-Fiume G, Collins-McMillen D, Gianni T, Yurochko AD. Integrins as Herpesvirus Receptors and Mediators of the Host Signalosome. Annu Rev Virol 2016; 3:215-236. [PMID: 27501260 DOI: 10.1146/annurev-virology-110615-035618] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The repertoire of herpesvirus receptors consists of nonintegrin and integrin molecules. Integrins interact with the conserved glycoproteins gH/gL or gB. This interaction is a conserved biology across the Herpesviridae family, likely directed to promote virus entry and endocytosis. Herpesviruses exploit this interaction to execute a range of critical functions that include (a) relocation of nonintegrin receptors (e.g., herpes simplex virus nectin1 and Kaposi's sarcoma-associated herpesvirus EphA2), or association with nonintegrin receptors (i.e., human cytomegalovirus EGFR), to dictate species-specific entry pathways; (b) activation of multiple signaling pathways (e.g., Ca2+ release, c-Src, FAK, MAPK, and PI3K); and (c) association with Rho GTPases, tyrosine kinase receptors, Toll-like receptors, which result in cytoskeletal remodeling, differential cell type targeting, and innate responses. In turn, integrins can be modulated by viral proteins (e.g., Epstein-Barr virus LMPs) to favor spread of transformed cells. We propose that herpesviruses evolved a multipartite entry system to allow interaction with multiple receptors, including integrins, required for their sophisticated life cycle.
Collapse
Affiliation(s)
- Gabriella Campadelli-Fiume
- Department of Experimental, Diagnostic and Specialty Medicine, University of Bologna, 40126 Bologna, Italy;
| | - Donna Collins-McMillen
- Department of Microbiology and Immunology, Center for Molecular and Tumor Virology, and Center for Cardiovascular Diseases and Sciences, Louisiana State University Health Sciences Center, Shreveport, Louisiana 71130;
| | - Tatiana Gianni
- Department of Experimental, Diagnostic and Specialty Medicine, University of Bologna, 40126 Bologna, Italy;
| | - Andrew D Yurochko
- Department of Microbiology and Immunology, Center for Molecular and Tumor Virology, and Center for Cardiovascular Diseases and Sciences, Louisiana State University Health Sciences Center, Shreveport, Louisiana 71130; .,Feist-Weiller Cancer Center and Center for Excellence in Arthritis and Rheumatology, Louisiana State University Health Sciences Center, Shreveport, Louisiana 71130
| |
Collapse
|
19
|
Möhl BS, Chen J, Sathiyamoorthy K, Jardetzky TS, Longnecker R. Structural and Mechanistic Insights into the Tropism of Epstein-Barr Virus. Mol Cells 2016; 39:286-91. [PMID: 27094060 PMCID: PMC4844934 DOI: 10.14348/molcells.2016.0066] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Accepted: 03/26/2016] [Indexed: 01/23/2023] Open
Abstract
Epstein-Barr virus (EBV) is the prototypical γ-herpesvirus and an obligate human pathogen that infects mainly epithelial cells and B cells, which can result in malignancies. EBV infects these target cells by fusing with the viral and cellular lipid bilayer membranes using multiple viral factors and host receptor(s) thus exhibiting a unique complexity in its entry machinery. To enter epithelial cells, EBV requires minimally the conserved core fusion machinery comprised of the glycoproteins gH/gL acting as the receptor-binding complex and gB as the fusogen. EBV can enter B cells using gp42, which binds tightly to gH/gL and interacts with host HLA class II, activating fusion. Previously, we published the individual crystal structures of EBV entry factors, such as gH/gL and gp42, the EBV/host receptor complex, gp42/HLA-DR1, and the fusion protein EBV gB in a postfusion conformation, which allowed us to identify structural determinants and regions critical for receptor-binding and membrane fusion. Recently, we reported different low resolution models of the EBV B cell entry triggering complex (gHgL/gp42/HLA class II) in "open" and "closed" states based on negative-stain single particle electron microscopy, which provide further mechanistic insights. This review summarizes the current knowledge of these key players in EBV entry and how their structures impact receptor-binding and the triggering of gB-mediated fusion.
Collapse
Affiliation(s)
- Britta S. Möhl
- Department of Microbiology and Immunology, The Feinberg School of Medicine, Northwestern University, Chicago, Illinois,
USA
| | - Jia Chen
- Department of Microbiology and Immunology, The Feinberg School of Medicine, Northwestern University, Chicago, Illinois,
USA
| | - Karthik Sathiyamoorthy
- Department of Structural Biology, Stanford University School of Medicine, Stanford, California,
USA
| | - Theodore S. Jardetzky
- Department of Structural Biology, Stanford University School of Medicine, Stanford, California,
USA
| | - Richard Longnecker
- Department of Microbiology and Immunology, The Feinberg School of Medicine, Northwestern University, Chicago, Illinois,
USA
| |
Collapse
|
20
|
Heldwein EE. gH/gL supercomplexes at early stages of herpesvirus entry. Curr Opin Virol 2016; 18:1-8. [PMID: 26849495 DOI: 10.1016/j.coviro.2016.01.010] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Revised: 01/14/2016] [Accepted: 01/15/2016] [Indexed: 11/25/2022]
Abstract
Membrane fusion during herpesvirus entry into host cells is a complex process where multiple glycoproteins interact to relay the triggering signal from a receptor-binding protein to the conserved fusogen gB through the conserved heterodimer gH/gL. Crystal structures of individual glycoproteins are available, yet high-order 'supercomplexes' have been elusive. Recent structures of complexes between gH/gL from human cytomegalovirus or Epstein-Barr virus and the receptor-binding proteins that form at early stages of herpesviral entry highlighted mechanisms that control tropism and revealed dynamic intermediate complexes containing gH/gL that may directly participate in membrane deformation and juxtaposition. Determining how the triggering signal reaches the fusogen gB represents the next frontier in structural biology of herpesvirus entry.
Collapse
Affiliation(s)
- Ekaterina E Heldwein
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA 02111, USA.
| |
Collapse
|
21
|
Comparative Mutagenesis of Pseudorabies Virus and Epstein-Barr Virus gH Identifies a Structural Determinant within Domain III of gH Required for Surface Expression and Entry Function. J Virol 2015; 90:2285-93. [PMID: 26656711 DOI: 10.1128/jvi.03032-15] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Accepted: 12/03/2015] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Herpesviruses infect cells using the conserved core fusion machinery composed of glycoprotein B (gB) and gH/gL. The gH/gL complex plays an essential but still poorly characterized role in membrane fusion and cell tropism. Our previous studies demonstrated that the conserved disulfide bond (DB) C278/C335 in domain II (D-II) of Epstein-Barr virus (EBV) gH has an epithelial cell-specific function, whereas the interface of D-II/D-III is involved in formation of the B cell entry complex by binding to gp42. To extend these studies, we compared gH of the alphaherpesvirus pseudorabies virus (PrV) with gH of the gammaherpesvirus EBV to identify functionally equivalent regions critical for gH function during entry. We identified several conserved amino acids surrounding the conserved DB that connects three central helices of D-III of PrV and EBV gH. The present study verified that the conserved DB and several contacting amino acids in D-III modulate cell surface expression and thereby contribute to gH function. In line with this finding, we found that DB C404/C439 and T401 are important for cell-to-cell spread and efficient entry of PrV. This parallel comparison between PrV and EBV gH function brings new insights into how gH structure impacts fusion function during herpesvirus entry. IMPORTANCE The alphaherpesvirus PrV is known for its neuroinvasion, whereas the gammaherpesvirus EBV is associated with cancer of epithelial and B cell origin. Despite low amino acid conservation, PrV gH and EBV gH show strikingly similar structures. Interestingly, both PrV gH and EBV gH contain a structural motif composed of a DB and supporting amino acids which is highly conserved within the Herpesviridae. Our study verified that PrV gH uses a minimal motif with the DB as the core, whereas the DB of EBV gH forms extensive connections through hydrogen bonds to surrounding amino acids, ensuring the cell surface expression of gH/gL. Our study verifies that the comparative analysis of distantly related herpesviruses, such as PrV and EBV, allows the identification of common gH functions. In addition, we provide an understanding of how functional domains can evolve over time, resulting in subtle differences in domain structure and function.
Collapse
|
22
|
Mutations in Pseudorabies Virus Glycoproteins gB, gD, and gH Functionally Compensate for the Absence of gL. J Virol 2015; 90:2264-72. [PMID: 26656712 DOI: 10.1128/jvi.02739-15] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Accepted: 12/03/2015] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Entry of herpesviruses depends on the combined action of viral glycoprotein B (gB) and the heterodimeric gH/gL complex, which are activated by binding of the virion to specific cellular receptors. While gB carries signatures of a bona fide fusion protein, efficient membrane fusion requires gH/gL. However, although gB and gH/gL are essential for entry, the alphaherpesvirus pseudorabies virus (PrV) is capable of limited cell-to-cell spread in the absence of gL. To understand gH/gL function in more detail, the limited spread of PrV-ΔgL was used for reversion analyses by serial cell culture passages. In a first experiment, an infectious gL-negative mutant in which gL function was replaced by generation of a gD-gH hybrid protein was isolated (B. G. Klupp and T. C. Mettenleiter, J Virol 73:3014-3022, 1999). In a second, independent experiment PrV-ΔgLPassB4.1, which also replicated productively without gL, was isolated. Sequence analysis revealed mutations in gH but also in gB and gD. In a transfection-based fusion assay, two amino acid substitutions in the N-terminal part of gH(B4.1) (L(70)P and W(103)R) were found to be sufficient to compensate for lack of gL, while mutations present in gB(B4.1) enhanced fusogenicity. Coexpression of gB(B4.1) with the homologous gH(B4.1) resulted in strongly increased syncytium formation, which was further augmented by truncation of the gB(B4.1) C-terminal 29 amino acids. Nevertheless, gH was still required for membrane fusion. Surprisingly, coexpression of gD(B4.1) blocked syncytium formation in the fusion assays, which could be attributed to a V(106)A substitution within the ectodomain of gD(B4.1). IMPORTANCE In contrast to many other enveloped viruses, herpesviruses rely on the concerted action of four viral glycoproteins for membrane fusion during infectious entry. Although the highly conserved gB shows signatures of a fusion protein, for fusion induction it requires the gH/gL complex, whose role is still elusive. Here we demonstrated fusion activation by gH in the absence of gL after reversion analysis of gL-deleted pseudorabies virus. This gL-independent fusion activity depended on single amino acid exchanges affecting the gL-binding domain in gH, increasing fusogenicity in gB and allowing negative fusion regulation by gD. Thus, our results provide novel information on the interplay in the fusion machinery of herpesviruses.
Collapse
|
23
|
Abstract
Glycoproteins are critical to virus entry, to spread within and between hosts and can modify the behavior of cells. Many viruses carry only a few, most found in the virion envelope. EBV makes more than 12, providing flexibility in how it colonizes its human host. Some are dedicated to getting the virus through the cell membrane and on toward the nucleus of the cell, some help guide the virus back out and on to the next cell in the same or a new host. Yet others undermine host defenses helping the virus persist for a lifetime, maintaining a presence that is mostly tolerated and serves to perpetuate EBV as one of the most common infections of man.
Collapse
Affiliation(s)
- Lindsey M Hutt-Fletcher
- Department of Microbiology & Immunology, Feist-Weiller Cancer Center and Center for Molecular & Tumor Virology, Louisiana State University Health Sciences Center, 1501 Kings Highway, Shreveport, LA 71130, USA; Tel.: +1 318 675 4948
| |
Collapse
|
24
|
Zhao Y, Kong C, Wang Y. Multiple Comparison Analysis of Two New Genomic Sequences of ILTV Strains from China with Other Strains from Different Geographic Regions. PLoS One 2015; 10:e0132747. [PMID: 26186451 PMCID: PMC4505947 DOI: 10.1371/journal.pone.0132747] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2015] [Accepted: 06/17/2015] [Indexed: 01/01/2023] Open
Abstract
To date, twenty complete genome sequences of ILTV strains have been published in GenBank, including one strain from China, and nineteen strains from Australian and the United States. To investigate the genomic information on ILTVs from different geographic regions, two additional individual complete genome sequences of WG and K317 strains from China were determined. The genomes of WG and K317 strains were 153,505 and 153,639 bp in length, respectively. Alignments performed on the amino acid sequences of the twelve glycoproteins showed that 13 out of 116 mutational sites were present only among the Chinese strain WG and the Australian strains SA2 and A20. The phylogenetic tree analysis suggested that the WG strain established close relationships with the Australian strain SA2. The recombination events were detected and confirmed in different subregions of the WG strain with the sequences of SA2 and K317 strains as parental. In this study, two new complete genome sequences of Chinese ILTV strains were used in comparative analysis with other complete genome sequences of ILTV strains from China, the United States, and Australia. The analysis of genome comparison, phylogenetic trees, and recombination events showed close relationships among the Chinese strain WG and the Australian strains SA2. The information of the two new complete genome sequences from China will help to facilitate the analysis of phylogenetic relationships and the molecular differences among ILTV strains from different geographic regions.
Collapse
Affiliation(s)
- Yan Zhao
- Division of Avian Respiratory Disease Group, Harbin Veterinary Research Institute, The Chinese Academy of Agricultural Sciences, 427 Maduan Street, Harbin, China
| | - Congcong Kong
- Division of Avian Respiratory Disease Group, Harbin Veterinary Research Institute, The Chinese Academy of Agricultural Sciences, 427 Maduan Street, Harbin, China
| | - Yunfeng Wang
- Division of Avian Respiratory Disease Group, Harbin Veterinary Research Institute, The Chinese Academy of Agricultural Sciences, 427 Maduan Street, Harbin, China
- National Engineering Research Center of Veterinary Biologics, Harbin, China
- * E-mail:
| |
Collapse
|
25
|
A site of varicella-zoster virus vulnerability identified by structural studies of neutralizing antibodies bound to the glycoprotein complex gHgL. Proc Natl Acad Sci U S A 2015; 112:6056-61. [PMID: 25918416 PMCID: PMC4434712 DOI: 10.1073/pnas.1501176112] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Mapping neutralizing epitopes on viral entry glycoproteins allows the identification of potentially important functional regions. The structure of varicella-zoster virus (VZV) gHgL bound to two antibodies isolated from immune donors reveals a common binding site. Functional experiments demonstrate that the two antibodies neutralize VZV infection and inhibit glycoprotein gB/glycoprotein complex gHgL-mediated membrane fusion. Immunization experiments in mice demonstrate that VZV gHgL elicits potently neutralizing antibodies and confirm the key role of this antigenic site in antibody-mediated virus neutralization. This manuscript sheds light on the molecular mechanism of herpesvirus cell entry and will guide the design of subunit-based vaccines against VZV. Varicella-zoster virus (VZV), of the family Alphaherpesvirinae, causes varicella in children and young adults, potentially leading to herpes zoster later in life on reactivation from latency. The conserved herpesvirus glycoprotein gB and the heterodimer gHgL mediate virion envelope fusion with cell membranes during virus entry. Naturally occurring neutralizing antibodies against herpesviruses target these entry proteins. To determine the molecular basis for VZV neutralization, crystal structures of gHgL were determined in complex with fragments of antigen binding (Fabs) from two human monoclonal antibodies, IgG-94 and IgG-RC, isolated from seropositive subjects. These structures reveal that the antibodies target the same site, composed of residues from both gH and gL, distinct from two other neutralizing epitopes identified by negative-stain electron microscopy and mutational analysis. Inhibition of gB/gHgL-mediated membrane fusion and structural comparisons with herpesvirus homologs suggest that the IgG-RC/94 epitope is in proximity to the site on VZV gHgL that activates gB. Immunization studies proved that the anti-gHgL IgG-RC/94 epitope is a critical target for antibodies that neutralize VZV. Thus, the gHgL/Fab structures delineate a site of herpesvirus vulnerability targeted by natural immunity.
Collapse
|
26
|
Structural and biochemical studies of HCMV gH/gL/gO and Pentamer reveal mutually exclusive cell entry complexes. Proc Natl Acad Sci U S A 2015; 112:1767-72. [PMID: 25624487 DOI: 10.1073/pnas.1424818112] [Citation(s) in RCA: 116] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Human cytomegalovirus (HCMV) is a major cause of morbidity and mortality in transplant patients and the leading viral cause of birth defects after congenital infection. The glycoprotein complexes gH/gL/gO and gH/gL/UL128/UL130/UL131A (Pentamer) are key targets of the human humoral response against HCMV and are required for HCMV entry into fibroblasts and endothelial/epithelial cells, respectively. We expressed and characterized soluble forms of gH/gL, gH/gL/gO, and Pentamer. Mass spectrometry and mutagenesis analysis revealed that gL-Cys144 forms disulfide bonds with gO-Cys351 in gH/gL/gO and with UL128-Cys162 in the Pentamer. Notably, Pentamer harboring the UL128-Cys162Ser/gL-Cys144Ser mutations had impaired syncytia formation and reduced interference of HCMV entry into epithelial cells. Electron microscopy analysis showed that HCMV gH/gL resembles HSV gH/gL and that gO and UL128/UL130/UL131A bind to the same site at the gH/gL N terminus. These data are consistent with gH/gL/gO and Pentamer forming mutually exclusive cell entry complexes and reveal the overall location of gH/gL-, gH/gL/gO-, and Pentamer-specific neutralizing antibody binding sites. Our results provide, to our knowledge, the first structural view of gH/gL/gO and Pentamer supporting the development of vaccines and antibody therapeutics against HCMV.
Collapse
|
27
|
Membrane anchoring of Epstein-Barr virus gp42 inhibits fusion with B cells even with increased flexibility allowed by engineered spacers. mBio 2015; 6:mBio.02285-14. [PMID: 25564465 PMCID: PMC4313908 DOI: 10.1128/mbio.02285-14] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED We recently described the architecture of the Epstein-Barr virus (EBV) fusion-triggering complex consisting of the EBV B cell receptor human leukocyte antigen (HLA) class II and the EBV-encoded proteins gp42 and gH/gL. The architecture of this structure positioned the main body of gp42, comprising the C-type lectin domain (CTLD), away from the membrane and distant from where the membrane-bound form of gp42 might be tethered. gp42 is a type II membrane glycoprotein, with functional gp42 formed by cleavage near the gp42 amino-terminal transmembrane domain. This cleavage results in an approximately 50-amino-acid unstructured region that is responsible for binding gH/gL with nanomolar affinity. Our previous studies had shown that membrane-bound gp42 is not functional in B cell fusion. To investigate whether we could restore gp42 function by extending it from the membrane, we introduced one, two, and four structured immunoglobulin-like domains from muscle protein titin into a membrane-bound form of gp42 and tested function in binding to gHgL and HLA class II and function in fusion. We hypothesized that cleavage of gp42 generates a soluble functional form that relieves steric hindrance imposed on gHgL by membrane-bound gp42. All of the linker mutants had a dominant-negative effect on gp42 function, indicating that gp42 fusion function could not be restored simply by the addition of one to four titin domains. IMPORTANCE Epstein-Barr virus (EBV) is associated with numerous diseases from benign mononucleosis to Burkitt's and Hodgkin's lymphoma, nasopharyngeal and gastric carcinoma, and lymphoproliferative disorders in patients with immune dysfunction resulting from immune suppression. Among the glycoproteins important for fusion, gp42, along with gH/gL, determines EBV tropism between epithelial and B cells. The function of gp42 is dependent on N-terminal cleavage, since membrane-bound gp42 cannot mediate fusion. We further investigated whether insertion of a linker into membrane-bound gp42 would relieve steric hindrance imposed on membrane-bound gp42 and restore fusion function. However, adding one, two, or four structured immunoglobulin-like domains to membrane gp42 did not restore fusion activity, indicating that the architecture and membrane orientation of the B cell fusion-triggering complex of EBV may be easily perturbed and that gp42 cleavage is essential for B cell fusion.
Collapse
|
28
|
Abstract
Epstein-Barr virus primarily, though not exclusively, infects B cells and epithelial cells. Many of the virus and cell proteins that are involved in entry into these two cell types in vitro have been identified, and their roles in attachment and fusion are being explored. This chapter discusses what is known about entry at the cellular level in vitro and describes what little is known about the process in vivo. It highlights some of the questions that still need to be addressed and considers some models that need further testing.
Collapse
Affiliation(s)
- Liudmila S Chesnokova
- Department of Microbiology and Immunology, Center for Molecular and Tumor Virology, Feist-Weiller Cancer Center, Louisiana State University Health Sciences Center, 1501 Kings Highway, Shreveport, LA, 71130, USA
| | - Ru Jiang
- Department of Microbiology and Immunology, Center for Molecular and Tumor Virology, Feist-Weiller Cancer Center, Louisiana State University Health Sciences Center, 1501 Kings Highway, Shreveport, LA, 71130, USA.,Department of Clinical Teaching and Training, Tianjin University of Traditional Chinese Medicine, 312 West Anshan Road, 300193, Nankai District, Tianjin, China
| | - Lindsey M Hutt-Fletcher
- Department of Microbiology and Immunology, Center for Molecular and Tumor Virology, Feist-Weiller Cancer Center, Louisiana State University Health Sciences Center, 1501 Kings Highway, Shreveport, LA, 71130, USA.
| |
Collapse
|
29
|
Chesnokova LS, Hutt-Fletcher LM. Epstein-Barr virus infection mechanisms. CHINESE JOURNAL OF CANCER 2014; 33:545-8. [PMID: 25322867 PMCID: PMC4244317 DOI: 10.5732/cjc.014.10168] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Epstein-Barr virus (EBV) infection occurs by distinct mechanisms across different cell types. EBV infection of B cells in vitro minimally requires 5 viral glycoproteins and 2 cellular proteins. By contrast, infection of epithelial cells requires a minimum of 3 viral glycoproteins, which are capable of interacting with one or more of 3 different cellular proteins. The full complement of proteins involved in entry into all cell types capable of being infected in vivo is unknown. This review discusses the events that occur when the virus is delivered into the cytoplasm of a cell, the players known to be involved in these events, and the ways in which these players are thought to function.
Collapse
Affiliation(s)
- Liudmila S Chesnokova
- Department of Microbiology and Immunology, Center for Molecular Tumor Virology and Feist-Weiller Cancer Center, Louisiana State University Health Sciences Center, Shreveport, LA 71130,
| | | |
Collapse
|
30
|
The conserved disulfide bond within domain II of Epstein-Barr virus gH has divergent roles in membrane fusion with epithelial cells and B cells. J Virol 2014; 88:13570-9. [PMID: 25231307 DOI: 10.1128/jvi.02272-14] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
UNLABELLED Epstein-Barr virus (EBV) infects target cells via fusion with cellular membranes. For entry into epithelial cells, EBV requires the herpesvirus conserved core fusion machinery, composed of glycoprotein B (gB) and gH/gL. In contrast, for B cell fusion it requires gB and gH/gL with gp42 serving as a cell tropism switch. The available crystal structures for gH/gL allow the targeted analysis of structural determinants of gH to identify functional regions critical for membrane fusion. Domain II of EBV gH contains two disulfide bonds (DBs). The first is unique for EBV and closely related gammaherpesviruses. The second is conserved across the beta- and gammaherpesviruses and is positioned to stabilize a putative syntaxin-like bundle motif. To analyze the role of these DBs in membrane fusion, gH was mutated by amino acid substitution of the DB cysteines. Mutation of the EBV-specific DB resulted in diminished gH/gL cell surface expression that correlated with diminished B cell and epithelial cell fusion. In contrast, mutation of the conserved DB resulted in wild-type-like B cell fusion, whereas epithelial cell fusion was greatly reduced. The gH mutants bound well to gp42 but had diminished binding to epithelial cells. Tyrosine 336, located adjacent to cysteine 335 of the conserved DB, also was found to be important for DB stabilization and gH/gL function. We conclude that the conserved DB has a cell type-specific function, since it is important for the binding of gH to epithelial cells initiating epithelial cell fusion but not for fusion with B cells and gp42 binding. IMPORTANCE EBV predominantly infects epithelial and B cells in humans, which can result in EBV-associated cancers, such as Burkitt and Hodgkin lymphoma, as well as nasopharyngeal carcinoma. EBV is also associated with a variety of lymphoproliferative disorders, typically of B cell origin, observed in immunosuppressed individuals, such as posttransplant or HIV/AIDS patients. The gH/gL complex plays an essential but still poorly characterized role as an important determinant for EBV cell tropism. In the current studies, we found that mutants in the DB C278/C335 and the neighboring tyrosine 336 have cell type-specific functional deficits with selective decreases in epithelial cell, but not B cell, binding and fusion. The present study brings new insights into the gH function as a determinant for epithelial cell tropism during herpesvirus-induced membrane fusion and highlights a specific gH motif required for epithelial cell fusion.
Collapse
|
31
|
Epstein-Barr virus glycoprotein gB and gHgL can mediate fusion and entry in trans, and heat can act as a partial surrogate for gHgL and trigger a conformational change in gB. J Virol 2014; 88:12193-201. [PMID: 25142593 DOI: 10.1128/jvi.01597-14] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
UNLABELLED Epstein-Barr virus (EBV) fusion with an epithelial cell requires virus glycoproteins gHgL and gB and is triggered by an interaction between gHgL and integrin αvβ5, αvβ6, or αvβ8. Fusion with a B cell requires gHgL, gp42, and gB and is triggered by an interaction between gp42 and human leukocyte antigen class II. We report here that, like alpha- and betaherpesviruses, EBV, a gammaherpesvirus, can mediate cell fusion if gB and gHgL are expressed in trans. Entry of a gH-null virus into an epithelial cell is possible if the epithelial cell expresses gHgL, and entry of the same virus, which phenotypically lacks gHgL and gp42, into a B cell expressing gHgL is possible in the presence of a soluble integrin. Heat is capable of inducing the fusion of cells expressing only gB, and the proteolytic digestion pattern of gB in virions changes in the same way following the exposure of virus to heat or to soluble integrins. It is suggested that the Gibbs free energy released as a result of the high-affinity interaction of gHgL with an integrin contributes to the activation energy required to cause the refolding of gB from a prefusion to a postfusion conformation. IMPORTANCE The core fusion machinery of herpesviruses consists of glycoproteins gB and gHgL. We demonstrate that as in alpha- and betaherpesvirus, gB and gHgL of the gammaherpesvirus EBV can mediate fusion and entry when expressed in trans in opposing membranes, implicating interactions between the ectodomains of the proteins in the activation of fusion. We further show that heat and exposure to a soluble integrin, both of which activate fusion, result in the same changes in the proteolytic digestion pattern of gB, possibly representing the refolding of gB from its prefusion to its postfusion conformation.
Collapse
|
32
|
The Epstein-Barr virus (EBV) glycoprotein B cytoplasmic C-terminal tail domain regulates the energy requirement for EBV-induced membrane fusion. J Virol 2014; 88:11686-95. [PMID: 25100836 DOI: 10.1128/jvi.01349-14] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
The entry of enveloped viruses into host cells is preceded by membrane fusion, which in Epstein-Barr virus (EBV) is thought to be mediated by the refolding of glycoprotein B (gB) from a prefusion to a postfusion state. In our current studies, we characterized a gB C-terminal tail domain (CTD) mutant truncated at amino acid 843 (gB843). This truncation mutant is hyperfusogenic as monitored by syncytium formation and in a quantitative fusion assay and is dependent on gH/gL for fusion activity. gB843 can rescue the fusion function of other glycoprotein mutants that have null or decreased fusion activity in epithelial and B cells. In addition, gB843 requires less gp42 and gH/gL for fusion, and can function in fusion at a lower temperature than wild-type gB, indicating a lower energy requirement for fusion activation. Since a key step in fusion is the conversion of gB from a prefusion to an active postfusion state by gH/gL, gB843 may access this activated gB state more readily. Our studies indicate that the gB CTD may participate in the fusion function by maintaining gB in an inactive prefusion form prior to activation by receptor binding. Importance: Diseases resulting from Epstein-Barr virus (EBV) infection in humans range from the fairly benign disease infectious mononucleosis to life-threatening cancer. As an enveloped virus, EBV must fuse with a host cell membrane for entry and infection by using glycoproteins gH/gL, gB, and gp42. Among these glycoproteins, gB is thought to be the protein that executes fusion. To further characterize the function of the EBV gB cytoplasmic C-terminal tail domain (CTD) in fusion, we used a previously constructed CTD truncation mutant and studied its fusion activity in the context of other EBV glycoprotein mutants. From these studies, we find that the gB CTD regulates fusion by altering the energy requirements for the triggering of fusion mediated by gH/gL or gp42. Overall, our studies may lead to a better understanding of EBV fusion and entry, which may result in novel therapies that target the EBV entry step.
Collapse
|
33
|
Kong C, Zhao Y, Cui X, Zhang X, Cui H, Xue M, Wang Y. Complete genome sequence of the first Chinese virulent infectious laryngotracheitis virus. PLoS One 2013; 8:e70154. [PMID: 23922947 PMCID: PMC3726392 DOI: 10.1371/journal.pone.0070154] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2013] [Accepted: 06/16/2013] [Indexed: 01/22/2023] Open
Abstract
Infectious laryngotracheitis (ILT) is an acute respiratory disease caused by infectious laryngotracheitis virus (ILTV). The complete genome sequences of five attenuated ILTV vaccine strains and six virulent ILTV strains as well as two Australian ILTV field strains have been published in Australia and the USA so far. To provide the complete genome sequence information of ILTVs from different geographic regions, the whole genome of ILTV LJS09 isolated in China was sequenced. The genome of ILTV LJS09 was 153,201 bp in length, and contained 79 ORFs. Most of the ORFs had high sequence identity with homologous ORFs of reference strains. There was a large fragment deletion within the noncoding region of unique long region (UL) of ILTV LJS09 compared with SA2 and A20 strains. Though the origin binding protein of ILTV LJS09 existed, there was no AT-rich region in strain LJS09. Alignments of the amino acid sequences revealed seven mutations at amino acids 71 (Arg → Lys), 116 (Ala → Val), 207 (Thr → Ile) and 644 (Thr → Ile) on glycoprotein B, 155 (Phe → Ser) and 376 (Arg → His) on glycoprotein D and 8 (Gln→Pro) on glycoprotein L of ILTV LJS09 compared to those of virulent strain (USDA) as ILTV LJS09 did not grow on chicken embryo fibroblasts, suggesting the role of the key seven amino acids in determination of the cell tropism of ILTV LJS09. This is the first complete genome sequence of the virulent strain of ILTV in Asia using the conventional PCR method, which will help to facilitate the future molecular biological research of ILTVs.
Collapse
Affiliation(s)
- Congcong Kong
- Division of Avian Infectious Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, The Chinese Academy of Agricultural Sciences, Harbin, China
- National Engineering Research Center of Veterinary Biologics, Harbin, China
| | - Yan Zhao
- Division of Avian Infectious Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, The Chinese Academy of Agricultural Sciences, Harbin, China
- National Engineering Research Center of Veterinary Biologics, Harbin, China
| | - Xianlan Cui
- Animal Health Laboratory, Department of Primary Industries, Parks, Water and Environment, Prospect, Tasmania, Australia
| | - Xiaomin Zhang
- Institute of Animal Science and Technology, Yunnan Agricultural University, Kunming, China
| | - Hongyu Cui
- Division of Avian Infectious Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, The Chinese Academy of Agricultural Sciences, Harbin, China
- National Engineering Research Center of Veterinary Biologics, Harbin, China
| | - Mei Xue
- Division of Avian Infectious Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, The Chinese Academy of Agricultural Sciences, Harbin, China
- National Engineering Research Center of Veterinary Biologics, Harbin, China
| | - Yunfeng Wang
- Division of Avian Infectious Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, The Chinese Academy of Agricultural Sciences, Harbin, China
- National Engineering Research Center of Veterinary Biologics, Harbin, China
| |
Collapse
|
34
|
Identification of the human herpesvirus 6A gQ1 domain essential for its functional conformation. J Virol 2013; 87:7054-63. [PMID: 23596294 DOI: 10.1128/jvi.00611-13] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Human herpesvirus 6 is a T lymphotropic herpesvirus, long classified into variants A and B (HHV-6A and HHV-6B) based on differences in sequence and pathogenicity. Recently, however, HHV-6A and HHV-6B were reclassified as different species. Here, we isolated a neutralizing monoclonal antibody (Mab) named AgQ 1-1 that was specific for HHV-6A glycoprotein Q1 (AgQ1), and we showed that amino acid residues 494 to 497 of AgQ1 were critical for its recognition by this Mab. This region was also essential for AgQ1's complex formation with gH, gL, and gQ2, which might be important for viral binding to the cellular receptor, CD46. In addition, amino acid residues 494 to 497 are essential for viral replication. Interestingly, this sequence corresponds to the domain on HHV-6B gQ1 that is critical for recognition by an HHV-6B-specific neutralizing Mab. Within this domain, only Q at position 496 of HHV-6A is distinct from the HHV-6B sequence; however, the mutant AgQ1(Q496E) was still clearly recognized by the Mab AgQ 1-1. Surprisingly, replacement of the adjacent amino acid, in mutant AgQ1(C495A), resulted in poor recognition by Mab AgQ 1-1, and AgQ1(C495A) could not form the gH/gL/gQ1/gQ2 complex. Furthermore, the binding ability of mutant AgQ1(L494A) with CD46 decreased, although it could form the gH/gL/gQ1/gQ2 complex and it showed clear reactivity to Mab AgQ 1-1. These data indicated that amino acid residues 494 to 497 of AgQ1 were critical for the recognition by Mab AgQ 1-1 and essential for AgQ1's functional conformation.
Collapse
|