Potent human single domain antibodies specific for a novel prefusion epitope of RSV F glycoprotein

Respiratory syncytial virus (RSV) poses great health threats to humans. However, there are no licensed vaccines or therapeutic drugs to date. Only one humanized monoclonal antibody, palivizumab, is available on the market, but it is used prophylactically and is limited to infants under high risk. With advances in antibody engineering, it has been found that single domain antibody (sdAb) can be therapeutically administered by inhalation, which would be more efficient for respiratory diseases. Here, we identified two human sdAbs, m17 and m35, by phage display technology. They specifically bind to RSV F in the prefusion state with subnanomolar affinity and potently neutralize both RSV subtypes A and B with IC 50 values ranging from pM to nM. Interestingly, these sdAbs recognize a novel epitope termed VI that is unique to the prefusion state. This epitope is located at the C-terminus of the F1 subunit, close to the viral membrane, and might be sterically restricted. We further find that m17 and m35 neutralize RSV by preventing the prefusion F conformational arrangement, thus inhibiting membrane fusion. These two sdAbs have the potential to be further developed as therapeutic candidates, and may also provide novel insight for developing other antiviral reagents against RSV. Importance Because RSV can cause serious respiratory disease in immunodeficient groups, including infants and seniors, the development of vaccines and therapeutic drugs, like neutralizing antibodies, is urgently needed. Compared to the conventional full-length antibody, single domain antibody (sdAb) has been demonstrated to be efficient for respiratory diseases when administered by inhalation, thereby potentially introducing a kind of novel therapeutic agent in the market. Here, we discovered two potent neutralizing human sdAbs against RSV that recognized a novel prefusion epitope termed VI and prevented conformational arrangement during the fusion process. Our work provides not only therapeutic candidates but also novel target for new drug and vaccine development.

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A vulnerable, membrane-proximal site in human respiratory syncytial virus F revealed by a prefusion-specific single-domain antibody

Journal of Virology ◽

10.1128/jvi.02279-20 ◽

2021 ◽

Author(s):

Iebe Rossey ◽

Ching-Lin Hsieh ◽

Koen Sedeyn ◽

Marlies Ballegeer ◽

Bert Schepens ◽

...

Keyword(s):

Respiratory Syncytial Virus ◽

Neutralizing Antibodies ◽

Antigenic Site ◽

Human Respiratory Syncytial Virus ◽

Single Domain ◽

Respiratory Pathogen ◽

Single Domain Antibody ◽

Domain Antibody ◽

Proximal Site ◽

Syncytial Virus

Human respiratory syncytial virus (RSV) is a major cause of lower respiratory tract disease, especially in young children and the elderly. The fusion protein (F) exists in a pre- and postfusion conformation and is the main target of RSV-neutralizing antibodies. Highly potent RSV-neutralizing antibodies typically bind sites that are unique to the prefusion conformation of F. In this study we screened a single-domain antibody (VHH) library derived from a llama immunized with prefusion-stabilized F and identified a prefusion F-specific VHH that can neutralize RSV A at subnanomolar concentrations. Structural analysis revealed that this VHH primarily binds to antigenic site I while also making contacts with residues in antigenic site III and IV. This new VHH reveals a previously underappreciated membrane-proximal region sensitive for neutralization. Importance RSV is an important respiratory pathogen. This study describes a prefusion F-specific VHH that primarily binds to antigenic site I of RSV F. This is the first time that a prefusion F-specific antibody that binds this site is reported. In general, antibodies that bind to site I are poorly neutralizing, whereas the VHH described here neutralizes RSV A at subnanomolar concentrations. Our findings contribute to insights into the RSV F antigenic map.

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Single-domain antibody fragments derived from heavy-chain antibodies: a review

Veterinární Medicína ◽

10.17221/6336-vetmed ◽

2012 ◽

Vol 57 (No. 9) ◽

pp. 439-513 ◽

Cited By ~ 40

Author(s):

L. Eyer ◽

K. Hruska

Keyword(s):

Heavy Chain ◽

Water Solubility ◽

Review Article ◽

Single Domain ◽

Single Domain Antibody ◽

Therapeutic Drugs ◽

Domain Antibody ◽

Application Potential ◽

New Generation ◽

Recombinant Fragments

Single-domain antibody (sdAb) fragments derived from heavy-chain antibodies of camelids and cartilaginous fish represent a new generation of therapeutic agents and immunoreagents. Due to their unique characteristics, such as low molecular weight, high physical-chemical stability, good water solubility, and the ability to bind antigens inaccessible to conventional antibodies, they could potentially act as a substitute for conventional therapeutic drugs in the treatment of serious human diseases, and, moreover, could be broadly used in analyses and diagnostics. In this review article, an analysis of 826 publications oriented to heavy-chain antibodies and their sdAb fragments indexed in the Web of Science<sup>®</sup> database since 1993 has been carried out. Attention has predominantly been paid to papers published from 2010 to June 2012. Key publications are presented in tables and are characterised by descriptive words, abstracts and references. The presented publications have been sorted according to seven basic criteria: review articles and monographs, heavy-chain antibodies of camelids and sharks, production of sdAb fragments using recombinant technology, characteristic properties of sdAb fragments, application of sdAb fragments in therapy, application of sdAb fragments in diagnostic and immunoanalytical methods and other prospective uses of sdAb fragments. This review article should highlight the typical properties of heavy-chain antibodies and sdAb fragments which differentiate them from conventional antibodies and other available recombinant fragments, and also emphasize their extremely broad application potential, mainly in human disease therapy. At the same time it allows an easy and rapid orientation in numerous publications written on this subject, and facilitates the search for the required data.

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Broad neutralization of SARS-CoV-2 variants by an inhalable bispecific single-domain antibody

10.1101/2021.12.30.474535 ◽

2021 ◽

Author(s):

Cheng Li ◽

Wuqiang Zhan ◽

Zhenlin Yang ◽

Chao Tu ◽

Yuanfei Zhu ◽

...

Keyword(s):

Virus Infection ◽

Neutralizing Antibodies ◽

Respiratory Virus ◽

Single Domain ◽

Therapeutic Antibodies ◽

Broadly Neutralizing Antibodies ◽

Single Domain Antibody ◽

Domain Antibody ◽

Cryptic Epitope ◽

Respiratory Virus Infection

The effectiveness of SARS-CoV-2 vaccines and therapeutic antibodies has been limited by the continuous emergence of viral variants, and by the restricted diffusion of antibodies from circulation into the sites of respiratory virus infection. Here, we report the identification of two highly conserved regions on Omicron variant RBD recognized by broadly neutralizing antibodies. Based on this finding, we generated a bispecific single-domain antibody that was able to simultaneously and synergistically bind these two regions on a single Omicron variant RBD as revealed by Cryo-EM structures. This inhalable antibody exhibited exquisite neutralization breadth and therapeutic efficacy in mouse models of SARS-CoV-2 infections. The structures also deciphered an uncommon cryptic epitope within the spike trimeric interface that may have implications for the design of broadly protective SARS-CoV-2 vaccines and therapeutics.

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Faculty Opinions recommendation of Crystal structure of a shark single-domain antibody V region in complex with lysozyme.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1024018.285841 ◽

2005 ◽

Author(s):

Christopher Garcia

Keyword(s):

Crystal Structure ◽

Single Domain ◽

Single Domain Antibody ◽

Domain Antibody ◽

V Region

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CAR T cells targeting CD13 controllably induce eradication of acute myeloid leukemia with a single domain antibody switch

Leukemia ◽

10.1038/s41375-021-01208-2 ◽

2021 ◽

Author(s):

Xin He ◽

Zijie Feng ◽

Jian Ma ◽

Xuyao Zhang ◽

Sunbin Ling ◽

...

Keyword(s):

T Cells ◽

Acute Myeloid Leukemia ◽

Myeloid Leukemia ◽

Single Domain ◽

Single Domain Antibody ◽

Car T Cells ◽

Domain Antibody ◽

Car T ◽

Acute Myeloid

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Production, characterization and in-vitro applications of single-domain antibody against thyroglobulin selected from novel T7 phage display library

Journal of Immunological Methods ◽

10.1016/j.jim.2021.112990 ◽

2021 ◽

Vol 492 ◽

pp. 112990

Author(s):

Jothivel Kumarasamy ◽

Samar Kumar Ghorui ◽

Chandrakala Gholve ◽

Bharti Jain ◽

Yogesh Dhekale ◽

...

Keyword(s):

Phage Display ◽

Phage Display Library ◽

Single Domain ◽

Single Domain Antibody ◽

Domain Antibody ◽

T7 Phage Display ◽

T7 Phage

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A Single-Domain Antibody-Based Anti-PSMA Recombinant Immunotoxin Exhibits Specificity and Efficacy for Prostate Cancer Therapy

International Journal of Molecular Sciences ◽

10.3390/ijms22115501 ◽

2021 ◽

Vol 22 (11) ◽

pp. 5501

Author(s):

Yutong Xing ◽

Keyuan Xu ◽

Shixiong Li ◽

Li Cao ◽

Yue Nan ◽

...

Keyword(s):

Prostate Cancer ◽

Animal Studies ◽

Single Domain ◽

Soluble Form ◽

Therapeutic Window ◽

Single Domain Antibody ◽

Pseudomonas Exotoxin A ◽

Simple Strategy ◽

Domain Antibody ◽

Recombinant Immunotoxin

Prostate cancer (PCa) is the second most common cancer in men, causing more than 300,000 deaths every year worldwide. Due to their superior cell-killing ability and the relative simplicity of their preparation, immunotoxin molecules have great potential in the clinical treatment of cancer, and several such molecules have been approved for clinical application. In this study, we adopted a relatively simple strategy based on a single-domain antibody (sdAb) and an improved Pseudomonas exotoxin A (PE) toxin (PE24X7) to prepare a safer immunotoxin against prostate-specific membrane antigen (PSMA) for PCa treatment. The designed anti-PSMA immunotoxin, JVM-PE24X7, was conveniently prepared in its soluble form in an Escherichia coli (E. coli) system, avoiding the complex renaturation process needed for immunotoxin preparation by the conventional strategy. The product was very stable and showed a very strong ability to bind the PSMA receptor. Cytotoxicity assays showed that this molecule at a very low concentration could kill PSMA-positive PCa cells, with an EC50 value (concentration at which the cell viability decreased by 50%) of 15.3 pM against PSMA-positive LNCaP cells. Moreover, this molecule showed very good killing selectivity between PSMA-positive and PSMA-negative cells, with a selection ratio of more than 300-fold. Animal studies showed that this molecule at a very low dosage (5 × 0.5 mg/kg once every three days) completely inhibited the growth of PCa tumors, and the maximum tolerable dose (MTD) was more than 15 mg/kg, indicating its very potent tumor-treatment ability and a wide therapeutic window. Use of the new PE toxin, PE24X7, as the effector moiety significantly reduced off-target toxicity and improved the therapeutic window of the immunotoxin. The above results demonstrate that the designed anti-PSMA immunotoxin, JVM-PE24X7, has good application value for the treatment of PCa.

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