scholarly journals Identification of a Neutralizing Epitope within Antigenic Domain 5 of Glycoprotein B of Human Cytomegalovirus

2014 ◽  
Vol 89 (1) ◽  
pp. 361-372 ◽  
Author(s):  
Anna-Katharina Wiegers ◽  
Heinrich Sticht ◽  
Thomas H. Winkler ◽  
William J. Britt ◽  
Michael Mach
Keyword(s):  
Human Cytomegalovirus ◽  
Neutralizing Antibodies ◽  
Mutational Analysis ◽  
Antibody Responses ◽  
Health Concern ◽  
Glycoprotein B ◽  
Protective Capacity ◽  
Important Target ◽  
Hcmv Disease ◽  
Antigenic Domain

ABSTRACTHuman cytomegalovirus (HCMV) is an important, ubiquitous pathogen that causes severe clinical disease in immunocompromised individuals, such as organ transplant recipients and infants infectedin utero. The envelope glycoprotein B (gB) of HCMV is a major antigen for the induction of virus-neutralizing antibodies. We have begun to define target structures within gB that are recognized by virus-neutralizing antibodies. Antigenic domain 5 (AD-5) of gB has been identified as an important target for neutralizing antibodies in studies using human monoclonal antibodies (MAbs). Anti-AD-5 MAbs share a target site on gB, despite originating from different, healthy, HCMV-infected donors. Mutational analysis of AD-5 identified tyrosine 280 in combination with other surface-exposed residues (the YNND epitope) as critical for antibody binding. The YNND epitope is strictly conserved among different HCMV strains. Recombinant viruses carrying YNND mutations in AD-5 were resistant to virus-neutralizing MAbs. Competition enzyme-linked immunosorbent assays (ELISAs) with human HCMV-convalescent-phase sera from unselected donors confirmed the conserved antibody response for the YNND epitope in HCMV-infected individuals and, because a significant fraction of the gB AD-5 response was directed against the YNND epitope, further argued that this epitope is a major target of anti-AD-5 antibody responses. In addition, affinity-purified polyclonal anti-AD-5 antibodies prepared from individual sera showed reactivity to AD-5 and neutralization activity toward gB mutant viruses that were similar to those of AD-5-specific MAbs. Taken together, our data indicate that the YNND epitope represents an important target for anti-gB antibody responses as well as for anti-AD-5 virus-neutralizing antibodies.IMPORTANCEHCMV is a major global health concern, and a vaccine to prevent HCMV disease is a widely recognized medical need. Glycoprotein B of HCMV is an important target for neutralizing antibodies and hence an interesting molecule for intervention strategies, e.g., vaccination. Mapping the target structures of neutralizing antibodies induced by naturally occurring HCMV infection can aid in defining the properties required for a protective capacity of vaccine antigens. The data presented here extend our knowledge of neutralizing epitopes within gB to include AD-5. Collectively, our data will contribute to optimal vaccine design and development of antibody-based therapies.

scholarly journals Cell Fusion Induced by a Fusion-Active Form of Human Cytomegalovirus Glycoprotein B (gB) Is Inhibited by Antibodies Directed at Antigenic Domain 5 in the Ectodomain of gB

2020 ◽  
Vol 94 (18) ◽  
Author(s):  
Nina Reuter ◽  
Barbara Kropff ◽  
Julia Karin Schneiderbanger ◽  
Mira Alt ◽  
Adalbert Krawczyk ◽  
...  
Keyword(s):  
Membrane Fusion ◽  
Human Cytomegalovirus ◽  
Neutralizing Antibodies ◽  
Hcmv Infection ◽  
Active Form ◽  
Health Concern ◽  
Glycoprotein B ◽  
Viral Fusion ◽  
Viral Fusion Protein ◽  
Antigenic Domain

ABSTRACT Human cytomegalovirus (HCMV) is a ubiquitous pathogen that can cause severe clinical disease in allograft recipients and infants infected in utero. Virus-neutralizing antibodies defined in vitro have been proposed to confer protection against HCMV infection, and the virion envelope glycoprotein B (gB) serves as a major target of neutralizing antibodies. The viral fusion protein gB is nonfusogenic on its own and requires glycoproteins H (gH) and L (gL) for membrane fusion, which is in contrast to requirements of related class III fusion proteins, including vesicular stomatitis virus glycoprotein G (VSV-G) or baculovirus gp64. To explore requirements for gB’s fusion activity, we generated a set of chimeras composed of gB and VSV-G or gp64, respectively. These gB chimeras were intrinsically fusion active and led to the formation of multinucleated cell syncytia when expressed in the absence of other viral proteins. Utilizing a panel of virus-neutralizing gB-specific monoclonal antibodies (MAbs), we could demonstrate that syncytium formation of the fusogenic gB/VSV-G chimera can be significantly inhibited by only a subset of neutralizing MAbs which target antigenic domain 5 (AD-5) of gB. This observation argues for differential modes of action of neutralizing anti-gB MAbs and suggests that blocking the membrane fusion function of gB could be one mechanism of antibody-mediated virus neutralization. In addition, our data have important implications for the further understanding of the conformation of gB that promotes membrane fusion as well as the identification of structures in AD-5 that could be targeted by antibodies to block this early step in HCMV infection. IMPORTANCE HCMV is a major global health concern, and antiviral chemotherapy remains problematic due to toxicity of available compounds and the emergence of drug-resistant viruses. Thus, an HCMV vaccine represents a priority for both governmental and pharmaceutical research programs. A major obstacle for the development of a vaccine is a lack of knowledge of the nature and specificities of protective immune responses that should be induced by such a vaccine. Glycoprotein B of HCMV is an important target for neutralizing antibodies and, hence, is often included as a component of intervention strategies. By generation of fusion-active gB chimeras, we were able to identify target structures of neutralizing antibodies that potently block gB-induced membrane fusion. This experimental system provides an approach to screen for antibodies that interfere with gB’s fusogenic activity. In summary, our data will likely contribute to both rational vaccine design and the development of antibody-based therapies against HCMV.

scholarly journals Antigenic Domain 1 Is Required for Oligomerization of Human Cytomegalovirus Glycoprotein B

2005 ◽  
Vol 79 (7) ◽  
pp. 4066-4079 ◽  
Author(s):  
William J. Britt ◽  
Michael A. Jarvis ◽  
Derek D. Drummond ◽  
Michael Mach
Keyword(s):  
Human Cytomegalovirus ◽  
Neutralizing Antibodies ◽  
Glycoprotein B ◽  
Structural Domain ◽  
Bacterial Artificial Chromosomes ◽  
Artificial Chromosomes ◽  
Antibody Binding Site ◽  
Virion Envelope ◽  
Antigenic Domain 1 ◽  
Antigenic Domain

ABSTRACT Human cytomegalovirus (HCMV) glycoprotein B (gB) is an abundant virion envelope protein that has been shown to be essential for the infectivity of HCMV. HCMV gB is also one of the most immunogenic virus-encoded proteins, and a significant fraction of virus neutralizing antibodies are directed at gB. A linear domain of gB designated AD-1 (antigenic domain 1) represents a dominant antibody binding site on this protein. AD-1 from clinical isolates of HCMV exhibits little sequence variation, suggesting that AD-1 plays an essential role in gB structure or function. We investigated this possibility by examining the role of AD-1 in early steps of gB synthesis. Our results from studies using eukaryotic cells indicated that amino acid (aa) 635 of the gB sequence represented the carboxyl-terminal limit of this domain and that deletion of aa 560 to 640 of the gB sequence resulted in loss of AD-1 expression. AD-1 was shown to be required for oligomerization of gB. Mutation of cysteine at either position 573 or 610 in AD-1 resulted in loss of its reactivity with AD-1-specific monoclonal antibodies and gB oligomerization. Infectious virus could not be recovered from HCMV bacterial artificial chromosomes following introduction of these mutations into the HCMV genome, suggesting that AD-1 was an essential structural domain required for gB function in the replicative cycle of HCMV. Sequence alignment of AD-1 with homologous regions of gBs from other herpesviruses demonstrated significant relatedness, raising the possibility that this domain may contribute to multimerization of gBs in other herpesviruses.

scholarly journals A divalent antibody format is required for neutralization of human cytomegalovirus via antigenic domain 2 on glycoprotein B

2002 ◽  
Vol 83 (8) ◽  
pp. 2001-2005 ◽  
Author(s):  
Johan Lantto ◽  
Jean M. Fletcher ◽  
Mats Ohlin
Keyword(s):  
Human Cytomegalovirus ◽  
Neutralizing Antibodies ◽  
Glycoprotein B ◽  
Human Antibody ◽  
Single Chain ◽  
Immunogenic Epitope ◽  
Neutralizing Capacity ◽  
Slow Dissociation ◽  
Kinetics Of ◽  
Antigenic Domain

Glycoprotein B (gB) of human cytomegalovirus (HCMV) is the dominating protein in the envelope of this virus and gives rise to virus-neutralizing antibodies in most infected individuals. We have previously isolated a neutralizing human antibody specific for antigenic domain 2 (AD-2) on gB, a poorly immunogenic epitope, which nevertheless is capable of eliciting potent neutralizing antibodies. In order to define parameters important for the neutralization of HCMV via gB, we have investigated the virus-neutralizing capacity and the kinetics of the interaction with AD-2 of the monomeric and dimeric forms of a single chain variable fragment (scFv) corresponding to this antibody. We demonstrate here that neutralization of HCMV via AD-2 on gB can be mediated by dimeric scFv, while monomeric fragments cannot mediate neutralization of the virus, despite a slow dissociation from the intact glycoprotein. This finding is discussed in the context of possible mechanisms for antibody-mediated virus neutralization.

Function of Human Cytomegalovirus Glycoprotein B: Syncytium Formation in Cells Constitutively Expressing gB Is Blocked by Virus-Neutralizing Antibodies

Virology ◽  
1994 ◽  
Vol 201 (2) ◽  
pp. 263-276 ◽  
Author(s):  
Sharof Tugizov ◽  
David Navarro ◽  
Pedro Paz ◽  
Yilong Wang ◽  
Ishtiaq Qadri ◽  
...  
Keyword(s):  
Human Cytomegalovirus ◽  
Neutralizing Antibodies ◽  
Syncytium Formation ◽  
Glycoprotein B ◽  
In Cells

scholarly journals Antigenic domain 1 of human cytomegalovirus glycoprotein B induces a multitude of different antibodies which, when combined, results in incomplete virus neutralization

1999 ◽  
Vol 80 (8) ◽  
pp. 2183-2191 ◽  
Author(s):  
Andrea Speckner ◽  
Diana Glykofrydes ◽  
Mats Ohlin ◽  
Michael Mach
Keyword(s):  
Human Cytomegalovirus ◽  
Neutralizing Antibodies ◽  
Natural Infection ◽  
Antibody Binding ◽  
Virus Neutralization ◽  
Single Amino Acid ◽  
Glycoprotein B ◽  
Considerable Proportion ◽  
Mutant Proteins ◽  
Neutralization Capacity

Glycoprotein B (gB, gpUL55) is the major antigen for the induction of neutralizing antibodies against human cytomegalovirus (HCMV), making it an attractive molecule for active and passive immunoprophylaxis. The region between aa 552 and 635 of HCMV gB (termed AD-1) has been identified as the immunodominant target for the humoral immune response following natural infection. AD-1 represents a complex domain which requires a minimal continuous sequence of more than 70 aa for antibody binding. Neutralizing as well as non-neutralizing antibodies can bind to AD-1 in a competitive fashion. The fine specificity of AD-1-binding monoclonal antibodies (MAbs) and affinity-purified human polyclonal antibodies was analysed by using recombinant proteins containing single amino acid substitutions spanning the entire AD-1 domain. Our results revealed that all MAbs had individual patterns of binding to the mutant proteins indicating the presence of a considerable number of distinct antibody-binding sites on AD-1. The neutralization capacity of antibodies could not be predicted from their binding pattern to AD-1 mutant proteins. Polyclonal human antibodies purified from different convalescent sera showed identical binding patterns to the mutant proteins suggesting that the combined antibody specificities present in human sera are comparable between individuals. Neutralization capacities of polyclonal human AD-1 antibodies did not exceed 50% indicating that, during natural infection, a considerable proportion of non-neutralizing antibodies are induced and thus might provide an effective mechanism to evade complete virus neutralization.

scholarly journals Antibodies Specific for the Antigenic Domain 1 of Glycoprotein B (gpUL55) of Human Cytomegalovirus Bind to Different Substructures

Virology ◽  
1996 ◽  
Vol 216 (1) ◽  
pp. 133-145 ◽  
Author(s):  
K. SCHOPPEL ◽  
E. HAßFURTHER ◽  
W. BRITT ◽  
M. OHLIN ◽  
C.A.K. BORREBAECK ◽  
...  
Keyword(s):  
Human Cytomegalovirus ◽  
Glycoprotein B ◽  
Antigenic Domain 1 ◽  
Antigenic Domain

scholarly journals The antigenic domain 1 of human cytomegalovirus glycoprotein B contains an intramolecular disulphide bond

2000 ◽  
Vol 81 (11) ◽  
pp. 2659-2663 ◽  
Author(s):  
Andrea Speckner ◽  
Barbara Kropff ◽  
Susanne Knör ◽  
Michael Mach
Keyword(s):  
Human Cytomegalovirus ◽  
Complex Structure ◽  
Active Form ◽  
Antibody Binding ◽  
Disulphide Bond ◽  
Glycoprotein B ◽  
Humoral Immune ◽  
Reducing Conditions ◽  
Antigenic Domain 1 ◽  
Antigenic Domain

Glycoprotein B (gB, gpUL55) is the major antigen recognized by the neutralizing humoral immune response against human cytomegalovirus (HCMV). The immunodominant region on gB is the antigenic domain 1 (AD-1), a complex structure that requires a minimal continuous sequence of more than 75 amino acids (aa 552–635) for antibody binding. In this study, the structural requirements for antibody binding to AD-1 have been determined. The domain was expressed in prokaryotic and eukaryotic systems and analysed in immunoblots under reducing and non-reducing conditions. In addition, AD-1 was purified in an immunologically active form and the concentration of sulphydryl groups was determined. The data clearly show that the only form that is recognized by antibodies is a disulphide-linked monomer of AD-1. The disulphide bond is formed between cysteines at amino acid positions 573 and 610 of gB.

scholarly journals Potent Bispecific Neutralizing Antibody Targeting Glycoprotein B and the gH/gL/pUL128/130/131 Complex of Human Cytomegalovirus

2020 ◽  
Vol 65 (3) ◽  
Author(s):  
Hang Su ◽  
Xiaohua Ye ◽  
Daniel C. Freed ◽  
Leike Li ◽  
Zhiqiang Ku ◽  
...  
Keyword(s):  
Human Cytomegalovirus ◽  
Neutralizing Antibodies ◽  
Developmental Disorders ◽  
Bispecific Antibody ◽  
Hcmv Infection ◽  
Rhesus Macaques ◽  
Congenital Infection ◽  
Neutralizing Antibody ◽  
Glycoprotein B ◽  
Single Chain

ABSTRACT Human cytomegalovirus (HCMV) is a ubiquitous pathogen that can cause developmental disorders following congenital infection and life-threatening complications among transplant patients. Potent neutralizing monoclonal antibodies (MAbs) are promising drug candidates against HCMV infection. HCMV can infect a broad range of cell types. Therefore, single neutralizing antibodies targeting one HCMV glycoprotein often lack either potency or broad cell-type coverage. We previously characterized two human-derived HCMV neutralizing MAbs. One was the broadly neutralizing MAb 3-25, which targets the antigenic domain 2 of glycoprotein B (gB). The other was the highly potent MAb 2-18, which specifically recognizes the gH/gL/pUL128/130/131 complex (pentamer). To combine the strengths of gB- and pentamer-targeting MAbs, we developed an IgG–single-chain variable fragment (scFv) bispecific antibody by fusing the 2-18 scFv to the heavy-chain C terminus of MAb 3-25. The resulting bispecific antibody showed high-affinity binding to both gB and pentamer. Functionally, the bispecific antibody demonstrated a combined neutralization breadth and potency of the parental MAbs in multiple cell lines and inhibited postinfection viral spreading. Furthermore, the bispecific antibody was easily produced in CHO cells at a yield above 1 g/liter and showed a single-dose pharmacokinetic profile comparable to that of parental MAb 3-25 in rhesus macaques. Importantly, the bispecific antibody retained broadly and potent neutralizing activity after 21 days in circulation. Taken together, our research provides a proof-of-concept study for developing bispecific neutralizing antibody therapies against HCMV infection.

Sign in / Sign up

Export Citation Format

Share Document