Monoclonal Antibodies Targeting the HR2 Domain and the Region Immediately Upstream of the HR2 of the S Protein Neutralize In Vitro Infection of Severe Acute Respiratory Syndrome Coronavirus

ABSTRACT We have previously shown that an Escherichia coli-expressed, denatured spike (S) protein fragment of the severe acute respiratory coronavirus, containing residues 1029 to 1192 which include the heptad repeat 2 (HR2) domain, was able to induce neutralizing polyclonal antibodies (C. T. Keng, A. Zhang, S. Shen, K. M. Lip, B. C. Fielding, T. H. Tan, C. F. Chou, C. B. Loh, S. Wang, J. Fu, X. Yang, S. G. Lim, W. Hong, and Y. J. Tan, J. Virol. 79:3289-3296, 2005). In this study, monoclonal antibodies (MAbs) were raised against this fragment to identify the linear neutralizing epitopes in the functional domain and to investigate the mechanisms involved in neutralization. Eighteen hybridomas secreting the S protein-specific MAbs were obtained. Binding sites of these MAbs were mapped to four linear epitopes. Two of them were located within the HR2 region and two immediately upstream of the HR2 domain. MAbs targeting these epitopes showed in vitro neutralizing activities and were able to inhibit cell-cell membrane fusion. These results provide evidence of novel neutralizing epitopes that are located in the HR2 domain and the spacer region immediately upstream of the HR2 of the S protein.

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Rational design of peptides for identification of linear epitopes and generation of neutralizing monoclonal antibodies against DKK2 for cancer therapy

Antibody Therapeutics ◽

10.1093/abt/tbaa004 ◽

2020 ◽

Vol 3 (2) ◽

pp. 63-70 ◽

Cited By ~ 1

Author(s):

Rongqing Zhao ◽

Qian Xiao ◽

Maohua Li ◽

Wenlin Ren ◽

Chenxi Xia ◽

...

Keyword(s):

Monoclonal Antibodies ◽

Tumor Growth ◽

Wnt Signaling ◽

Rational Design ◽

Polyclonal Antibodies ◽

Wnt Signaling Pathway ◽

Keyhole Limpet Hemocyanin ◽

Linear Epitopes

Abstract Dickkopf-related protein 2 (DKK2)is a member of the Dickkopf family in Wnt signaling pathway. Recently, we found that antibodies against DKK2 could activate natural killer (NK) and CD8+ T cells in tumors and inhibit tumor growth. In this paper, we report the rational design of peptides for identification of linear epitopes and generation of neutralizing monoclonal anti-DKK2 antibodies. To break the immune tolerance, we designed and chemically synthesized six peptides corresponding to different regions of DKK2 as immunogens and found five of them could generate mouse polyclonal antibodies that can bind to the active recombinant human DKK2 protein. Neutralizing mouse monoclonal antibodies (5F8 and 1A10) against human DKK2 were successfully developed by immunizing the mice with two different peptides (34KLNSIKSSL42 and 240KVWKDATYS248) conjugated to Keyhole limpet hemocyanin (KLH). The monoclonal antibodies not only abolish DKK2’s suppression of Wnt signaling in vitro but also inhibits tumor growth in vivo. Currently, those two mAbs are undergoing humanization as immunotherapy candidates and may offer a new drug for treatment of human cancers.

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Development of Murine Monoclonal Antibodies for the Immunohistochemical Diagnosis of Systemic Bovine Aspergillosis

Journal of Veterinary Diagnostic Investigation ◽

10.1177/104063879600800111 ◽

1996 ◽

Vol 8 (1) ◽

pp. 68-75 ◽

Cited By ~ 31

Author(s):

H. E. Jensen ◽

B. Aalbaek ◽

P. Lind ◽

H. V. Krogh ◽

P. L. Frandsen

Keyword(s):

Monoclonal Antibodies ◽

Polyclonal Antibodies ◽

Fungal Species ◽

Cross Reactivity ◽

Water Soluble ◽

Enzyme Linked Immunosorbent Assay ◽

Immunohistochemical Techniques ◽

Immunohistochemical Diagnosis ◽

Murine Monoclonal Antibodies

Murine monoclonal antibodies (MAbs) against water-soluble somatic antigens (WSSA) and the wall fraction (WF) from Aspergillus fumigatus were produced by fusion of splenocytes from immunized BALB/c mice with mouse myeloma X63-Ag 8.653 cells. The supernatants of in vitro cultured hybridomas were initially screened for reactivity with the WSSA and the WF from A. fumigatus and WSSA of other fungi in an enzyme-linked immunosorbent assay (ELISA). Supernatants reacting only with A. fumigatus antigens were subsequently screened for homologous and heterologous reactivity with immunohistochemical techniques using formalin-fixed, paraffin-embedded tissues from experimentally infected mice. Because of a high immunohistochemical reactivity with homologous fungi, 4 MAbs raised against A. fumigatus WSSA and WF were selected for a further evaluation of cross-reactivity (diagnostic specificity) in immunohistochemical and immunoblotting assays. In immunohistochemical assays, all MAbs raised against WSSA cross-reacted heavily with a number of other fungal species. All 4 MAbs (MAb-WF-AF-1-4) raised against the WF reacted strongly with hyphae of Aspergillus spp.; hyphae of Scedosporium apiospermum were also strongly labeled by MAb-WF-AF-3 and-4. The 2 specifically reacting MAbs (MAb-WF-AF-1 and-2) were of the IgM biotype and were precipitating, and in immunoblotting experiments both bound to a 106-kD antigen of the WF, whereas they did not bind to WSSA of A. fumigatus. One of the 2 aspergillosis-specific MAbs (MAb-WF-AF-1) was used to screen 145 mycotic lesions of cattle. The diagnoses on bovine lesions obtained by MAb-WF-AF-1 were compared with results based on reactivity with heterologously absorbed polyclonal antibodies and, for some lesions, to culture results. In the vast majority of lesions ( n = 133), the MAb-WF-AF-1 and the polyclonal anti-Aspergillus antibodies reacted in a similar pattern, i.e., positively in 41 aspergillosis lesions and negatively in 92 zygomycotic lesions. Hyphae in 3 of 12 lesions that were not stained by the polyclonal antibodies reacted with the specific MAb-WF-AF-1; i.e., aspergillosis was diagnosed. The characteristics of the 2 MAbs (MAb-WF-AF-1 and-2) raised against the WF of A. fumigatus in ELISA and immunoblotting and immunohistochemical assays justify their application for the in situ diagnosis of systemic aspergillosis of cattle.

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Potent Neutralization Antibodies Induced by a Recombinant Trimeric Spike Protein Vaccine Candidate Containing PIKA Adjuvant for COVID-19

Vaccines ◽

10.3390/vaccines9030296 ◽

2021 ◽

Vol 9 (3) ◽

pp. 296

Author(s):

Jiao Tong ◽

Chenxi Zhu ◽

Hanyu Lai ◽

Chunchao Feng ◽

Dapeng Zhou

Keyword(s):

Monoclonal Antibodies ◽

Vaccine Candidate ◽

Spike Protein ◽

Heptad Repeat ◽

Peptide Array ◽

Receptor Binding Domain ◽

Protein Vaccine ◽

Direct Binding ◽

Linear Epitopes ◽

Potent Neutralization

The structures of immunogens that elicit the most potent neutralization antibodies to prevent COVID-19 infection are still under investigation. In this study, we tested the efficacy of a recombinant trimeric Spike protein containing polyI:C (PIKA) adjuvant in mice immunized by a 0–7–14 day schedule. The results showed that a Spike protein-specific antibody was induced at Day 21 with titer of above 50,000 on average, as measured by direct binding. The neutralizing titer was above 1000 on average, as determined by a pseudo-virus using monoclonal antibodies (40592-MM57 and 40591-MM43) with IC50 at 1 μg/mL as standards. The protein/peptide array-identified receptor-binding domain (RBD) was considered as immunodominant. No linear epitopes were found in the RBD, although several linear epitopes were found in the C-terminal domain right after the RBD and heptad repeat regions. Our study supports the efficacy of a recombinant trimeric Spike protein vaccine candidate for COVID-19 that is safe and ready for storage and distribution in developing countries.

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XAV-19, a novel swine glyco-humanized polyclonal antibody against SARS-CoV-2 spike, efficiently neutralizes B.1.1.7 British and B.1.351 South-African variants.

10.1101/2021.04.02.437747 ◽

2021 ◽

Author(s):

Bernard Vanhove ◽

Stephane Sylvain Marot ◽

Benjamin Gaborit ◽

Gwenaelle Evanno ◽

Isabelle Malet ◽

...

Keyword(s):

South African ◽

Receptor Binding ◽

Polyclonal Antibody ◽

Polyclonal Antibodies ◽

S Protein ◽

Angiotensin Converting Enzyme 2 ◽

African Form ◽

The Uk ◽

The Impact

Amino acid substitutions and deletions in spike (S) protein of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants can reduce the effectiveness of monoclonal antibodies (mAbs). In contrast, heterologous polyclonal antibodies raised against S protein, through the recognition of multiple target epitopes, have the potential to maintain neutralization capacities. We report on XAV-19, a swine glyco-humanized polyclonal antibody (GH-pAb) raised against the receptor binding domain (RBD) of the Wuhan-Hu-1 spike protein of SARS-CoV-2. XAV-19 target epitopes are distributed all over the RBD and particularly cover the receptor binding motives (RBM), on direct contact sites with the Angiotensin Converting Enzyme-2 (ACE-2). Using spike/ACE2 interaction assays, we analyzed in vitro the impact of punctual and grouped mutations in the S protein corresponding to the B.1.1.7 (British form; UK) and B.1.351 (South-African form, SA) variants and recorded that neutralization by XAV-19 exhibited little if any sensitivity to these mutations. These results were confirmed by two independent tissue culture infective doses assays (TCID) showing 100% neutralization of the variants at close concentrations. XAV-19, which is currently evaluated in patients hospitalized for coronavirus disease 2019 (Covid-19) in the phase 2a-2b of the POLYCOR study (ClinicalTrial.gov, NCT04453384), may provide a novel effective therapeutic tool to combat coronavirus disease 2019 (Covid-19), caused by the original Wuhan form and by the UK/SA variants of concern.

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Characterization of a monoclonal antibody that probes the functional domains of the glucocorticoid receptor

Biochemical Journal ◽

10.1042/bj2460055 ◽

1987 ◽

Vol 246 (1) ◽

pp. 55-65 ◽

Cited By ~ 10

Author(s):

N M Robertson ◽

W F Kusmik ◽

B F Grove ◽

A Miller-Diener ◽

M L Webb ◽

...

Keyword(s):

Monoclonal Antibody ◽

Monoclonal Antibodies ◽

Glucocorticoid Receptor ◽

Glucocorticoid Receptors ◽

Enzyme Linked Immunosorbent Assay ◽

Functional Domain ◽

Cytoplasmic Staining ◽

Receptor Complexes ◽

Specificity And Sensitivity

Monoclonal antibodies to the rat hepatic glucocorticoid receptor (GR) were produced by using 4000-fold-purified unactivated rat hepatic GR as the immunogen in an immunization in vitro. Hybridomas were screened for anti-GR antibody production by using an enzyme-linked immunosorbent assay. The antibody, 3A6, described here, is an IgM (lambda). The interaction of 3A6 with the purified GR was explored by sedimentation analysis, where a shift of the 9 S GR to a form with a higher s20,w value was demonstrated. Binding specificity and sensitivity were demonstrated by protein immunoblotting. 3A6 cross-reacted with all rat tissue glucocorticoid receptors (GRs) examined, except those of the brain. Species cross-reactivity was observed with other mammalian GRs (from human CEM-C7 cells and from pig and mouse liver). Immunocytochemical localization of the GR was assessed by indirect immunofluorescence in intact fixed cells, which demonstrated intense cytoplasmic staining in the absence of pretreatment with glucocorticoids and nuclear localization when cells were pretreated with glucocorticoids. This monoclonal antibody significantly inhibited steroid binding to unoccupied receptor and DNA binding of activated steroid-receptor complexes. Furthermore, preincubation of the purified activated GR complex with 3A6 prevented phosphorylation of the GR in vitro. Thus 3A6 differs from previous monoclonal antibodies to the GR in its capacity to cross-react with the human GR and by its specificity for an epitope on or near a functional domain of the GR.

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Immunohistochemical Diagnosis of Systemic Bovine Zygomycosis by Murine Monoclonal Antibodies

Veterinary Pathology ◽

10.1177/030098589603300207 ◽

1996 ◽

Vol 33 (2) ◽

pp. 176-183 ◽

Cited By ~ 24

Author(s):

H. E. Jensen ◽

B. Aalbæk ◽

P. Lind ◽

H. V. Krogh

Keyword(s):

Monoclonal Antibodies ◽

Lymph Nodes ◽

Rhizopus Oryzae ◽

Polyclonal Antibodies ◽

Cross Reactivity ◽

Water Soluble ◽

Enzyme Linked Immunosorbent Assay ◽

The Family ◽

Murine Monoclonal Antibodies

Murine monoclonal antibodies (Mabs) against water-soluble somatic antigens (WSSA) and the wall fraction (WF) from Rhizopus arrhizus (Rhizopus oryzae) were produced in vitro by fusion of splenocytes from immunized BALB/c mice with mouse myeloma X63-Ag 8.653 cells. Supernatants reacting only with homologous antigens in an enzyme-linked immunosorbent assay were subsequently screened for reactivity with homologous fungi in immunohistochemical techniques. All four Mabs raised against the WF of A. arrhizus failed to react on tissues. However, four of the Mabs raised against the WSSA of R. arrhizus (Mab-WSSA-RA-1 through Mab-WSSA-RA-4) revealed a high homologous reactivity on tissues and the cross-reactivity of these were subsequently evaluated on tissues containing other members of the family Mucoraceae and other unrelated fungi. On tissues and on immunoblots all four Mabs reacted identically and specifically with members of the family Mucoraceae, i.e., Absidia corymbifera, R. arrhizus, and Rhizomucor pusillus. The Mabs were all isotyped as IgM antibodies, were nonprecipitating, and reacted with homologous antigens with molecular masses from 14 to 110 kDa. With WSSA from A. corymbifera and R. pusillus the four Mabs were bound to antigens from 14 to 52 kDa and from 20 to 28 kDa, respectively. The diagnosis of 145 bovine lesions obtained by one of the specific Mabs (Mab-WSSA-RA-1) were compared to results obtained by heterologously absorbed polyclonal antibodies. In most lesions ( n = 140 [∼ 97%]) the Mab and the polyclonal antibodies reacted in a similar pattern, i.e., positively for zygomycosis in 89 lesions, negatively in 41 aspergillosis lesions, and negatively in 10 undiagnosed lesions. Hyphae within two of four lesions in lymph nodes, which were not stained by the polyclonal antibodies, reacted with the specific Mab. However, in another three lesions of lymph nodes stained by the polyclonal antibodies no reactivity was seen with the Mab-WSSA-RA-1. The immunoreactivity of the Mabs (Mab-WSSA-RA-1 through Mab-WSSA-RA-4) raised against WSSA of R. arrhizus justify their application for the in situ diagnosis of systemic bovine zygomycosis.

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Analysis of the avian coronavirus spike protein reveals heterogeneity in the glycans present

Journal of General Virology ◽

10.1099/jgv.0.001642 ◽

2021 ◽

Vol 102 (8) ◽

Author(s):

Phoebe Stevenson-Leggett ◽

Stuart Armstrong ◽

Sarah Keep ◽

Paul Britton ◽

Erica Bickerton

Keyword(s):

Polyclonal Antibodies ◽

Laboratory Strain ◽

Host Cells ◽

Type I ◽

S Protein ◽

Infectious Bronchitis ◽

Glycan Profile ◽

Complex Glycans ◽

S Proteins

Infectious bronchitis virus (IBV) is an economically important coronavirus, causing damaging losses to the poultry industry worldwide as the causative agent of infectious bronchitis. The coronavirus spike (S) glycoprotein is a large type I membrane protein protruding from the surface of the virion, which facilitates attachment and entry into host cells. The IBV S protein is cleaved into two subunits, S1 and S2, the latter of which has been identified as a determinant of cellular tropism. Recent studies expressing coronavirus S proteins in mammalian and insect cells have identified a high level of glycosylation on the protein’s surface. Here we used IBV propagated in embryonated hens’ eggs to explore the glycan profile of viruses derived from infection in cells of the natural host, chickens. We identified multiple glycan types on the surface of the protein and found a strain-specific dependence on complex glycans for recognition of the S2 subunit by a monoclonal antibody in vitro, with no effect on viral replication following the chemical inhibition of complex glycosylation. Virus neutralization by monoclonal or polyclonal antibodies was not affected. Following analysis of predicted glycosylation sites for the S protein of four IBV strains, we confirmed glycosylation at 18 sites by mass spectrometry for the pathogenic laboratory strain M41-CK. Further characterization revealed heterogeneity among the glycans present at six of these sites, indicating a difference in the glycan profile of individual S proteins on the IBV virion. These results demonstrate a non-specific role for complex glycans in IBV replication, with an indication of an involvement in antibody recognition but not neutralisation.

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An Exposed Domain in the Severe Acute Respiratory Syndrome Coronavirus Spike Protein Induces Neutralizing Antibodies

Journal of Virology ◽

10.1128/jvi.78.13.7217-7226.2004 ◽

2004 ◽

Vol 78 (13) ◽

pp. 7217-7226 ◽

Cited By ~ 59

Author(s):

Tong Zhou ◽

Hong Wang ◽

Danlin Luo ◽

Thomas Rowe ◽

Zheng Wang ◽

...

Keyword(s):

Escherichia Coli ◽

Amino Acids ◽

Monoclonal Antibodies ◽

Severe Acute Respiratory Syndrome ◽

Neutralizing Antibodies ◽

Vaccine Development ◽

Vero Cells ◽

Spike Protein ◽

Protein Fragment

ABSTRACT Exposed epitopes of the spike protein may be recognized by neutralizing antibodies against severe acute respiratory syndrome (SARS) coronavirus (CoV). A protein fragment (S-II) containing predicted epitopes of the spike protein was expressed in Escherichia coli. The properly refolded protein fragment specifically bound to the surface of Vero cells. Monoclonal antibodies raised against this fragment recognized the native spike protein of SARS CoV in both monomeric and trimeric forms. These monoclonal antibodies were capable of blocking S-II attachment to Vero cells and exhibited in vitro antiviral activity. These neutralizing antibodies mapped to epitopes in two peptides, each comprising 20 amino acids. Thus, this region of the spike protein might be a target for generation of therapeutic neutralizing antibodies against SARS CoV and for vaccine development to elicit protective humoral immunity.

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Effect of Polyclonal, Monoclonal, and Recombinant (Single-Chain Variable Fragment) Antibodies on In Vitro Morphology, Growth, and Metabolism of the Phytopathogenic Mollicute Spiroplasma citri

Applied and Environmental Microbiology ◽

10.1128/aem.68.5.2113-2119.2002 ◽

2002 ◽

Vol 68 (5) ◽

pp. 2113-2119 ◽

Cited By ~ 12

Author(s):

Sylvie Malembic ◽

Colette Saillard ◽

Joseph M. Bové ◽

Monique Garnier

Keyword(s):

Monoclonal Antibodies ◽

Glucose Metabolism ◽

Control Strategy ◽

Polyclonal Antibodies ◽

Recombinant Antibodies ◽

Single Chain Variable Fragment ◽

Single Chain ◽

Inhibitory Effects ◽

Spiroplasma Citri

ABSTRACT Antibodies are known to affect the morphology, growth, and metabolism of mollicutes and thus may serve as candidate molecules for a plantibody-based control strategy for plant-pathogenic spiroplasmas and phytoplasmas. Recombinant single-chain variable fragment (scFv) antibodies are easy to engineer and express in plants, but their inhibitory effects on mollicutes have never been evaluated and compared with those of polyclonal and monoclonal antibodies. We describe the morphology, growth, and glucose metabolism of Spiroplasma citri in the presence of polyclonal, monoclonal, and recombinant antibodies directed against the immunodominant membrane protein spiralin. We showed that the scFv antibodies had no effect on S. citri glucose metabolism but were as efficient as polyclonal antibodies in inhibiting S. citri growth in liquid medium. Inhibition of motility was also observed.

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Simultaneous Quantitation of Antibodies to Neutralizing Epitopes on Virus-Like Particles for Human Papillomavirus Types 6, 11, 16, and 18 by a Multiplexed Luminex Assay

Clinical and Diagnostic Laboratory Immunology ◽

10.1128/cdli.10.1.108-115.2003 ◽

2003 ◽

Vol 10 (1) ◽

pp. 108-115 ◽

Cited By ~ 189

Author(s):

David Opalka ◽

Charles E. Lachman ◽

Stefani A. MacMullen ◽

Kathrin U. Jansen ◽

Judith F. Smith ◽

...

Keyword(s):

Human Papillomavirus ◽

Natural History ◽

Neutralizing Antibodies ◽

Polyclonal Antibodies ◽

Human Papillomaviruses ◽

Multiple Cancer ◽

Virus Like Particles ◽

Neutralizing Epitopes

ABSTRACT Several different methods have been developed to quantitate neutralizing antibody responses to human papillomaviruses (HPVs), including in vivo neutralization assays, in vitro pseudoneutralization assays, competitive radioimmunoassays (cRIAs), and enzyme-linked immunosorbent assays. However, each of these techniques possesses one or more limitations that preclude testing large numbers of patient sera for use in natural history studies and large vaccine clinical trials. We describe here a new multiplexed assay, by using the Luminex Laboratory MultiAnalyte Profiling (LabMAP3) assay system, that can simultaneously quantitate neutralizing antibodies to human papillomavirus types 6, 11, 16, and 18 in 50 μl of serum. The HPV-Luminex competitive immunoassay measures titers of polyclonal antibodies in serum capable of displacing phycoerythrin-labeled detection monoclonal antibodies binding to conformationally sensitive, neutralizing epitopes on the respective virus-like particles. This competitive Luminex immunoassay was found to be as sensitive, accurate, and precise as the currently used cRIAs. An effective HPV vaccine will most likely require several distinct genotypes to protect against multiple cancer causing papillomaviruses. The HPV-Luminex immunoassay should prove to be a useful tool in simultaneously quantitating antibody immune responses to multiple HPV genotypes for natural history infection studies and for monitoring the efficacy of prospective vaccines.

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