Nanobodies as novel agents for disease diagnosis and therapy

Nanobody-based indirect competitive ELISA for the detection of aflatoxin M1 in dairy products

Aflatoxin M1 (AFM1) is known to be carcinogenic, mutagenic, and teratogenic and poses a serious threat to food safety and human health, which makes its surveillance critical. In this study, an indirect competitive ELISA (icELISA) based on a nanobody (Nb M4) was developed for the sensitive and rapid detection of AFM1 in dairy products. In our previous work, Nb M4 was screened from a Bactrian-camel-immunized phage-displayed library. It exhibits VH-like features, possesses higher thermal stability than monoclonal antibody (mAb 1E6) and tightly binds to AFM1-BSA with a KD value of 2.5 nM. Under the optimal conditions, its half-maximal inhibitory concentration was 0.338 ng/mL, the limit of detection was 0.051 ng/mL, and linearity was noted in the range of 0.168-0.679 ng/mL. Nb M4 displayed almost no cross-reactivity with other mycotoxins. No matrix effect was observed in milk and milk powder samples, and the matrix effect in yogurt samples could be weakened by 2-fold dilution. Furthermore, validation studies in spiked samples (milk, yogurt, and milk powder) resulted in good recoveries of 95.40-111.33%, with a low coefficient of variation (2.89-6.78%). High-performance liquid chromatography was used to evaluate the accuracy and reliability of the developed icELISA, which indicated a satisfactory consistent correlation (R2 = 0.9722). This study highlights the potential of Nb M4 as a promising component for detecting AFM1 in dairy products.

A Simple Analysis of the Second (Extra) Disulfide Bridge of VHHs

Camelids produce a special type of antibody, known as VHHs, that has lost the VL domain, providing a more optimised VH domain. This particular highly stable antibody domain has interesting properties for biotechnological development. Ordinarily, those molecules possess only one disulphide bridge, but surprisingly, at least a quarter of these VHHs have a second one. Curiously, this does not seem to be essential for the stability and the function of this domain. In an attempt to characterise precisely the role and impact of this disulphide bridge at the molecular level, several in silico mutants of a VHH were created to disrupt this second disulphide bridge and those systems were submitted to molecular dynamics simulation. The loss of the second disulphide bridge leads to an increase in the flexibility of CDR1 and CDR3 and an unexpected rigidification of CDR2. Local conformational analysis shows local differences in the observed protein conformations. However, in fact, there is no exploration of new conformations but a change in the equilibrium between the different observed conformations. This explains why the interaction of VHHs is not really affected by the presence or absence of this second bridge, but their rigidity is slightly reduced. Therefore, the additional disulphide bridge does not seem to be an essential part of VHHs function.

Screening and identification of nanobody against inhibin α-subunit from a Camelus bactrianus phage display library

Background

Inhibin is a member of the transforming growth factor family that influences reproduction in animals.

Objective

The purpose of this study was to obtain nanobodies from the phage antibody library constructed by us that can specifically bind to inhibin α-subunit.

Methods

In this study, camels were immunized with Kazakh sheep inhibin-α protein that expressed in BL21 E. coli, and the camel VHH nanobody phage display library was prepared using nested PCR. The nanobodies specifically binding to inhibin α-subunit in the library were screened by three rounds of immunoaffinity screening and phage enzyme-linked immunosorbent assay (phage ELISA). The functions of the selected nanobodies were identified using molecular simulation docking, ELISA affinity test, and sheep immunity test.

Results

A nanobody display library was successfully constructed with a capacity of 1.05 × 1012 CFU, and four inhibin-α-subunit-specific nanobodies with an overall similarity of 69.34 % were screened from the library, namely, Nb-4, Nb-15, Nb-26, and Nb-57. The results of molecular simulation docking revealed that four types of nanobodies were complexed with inhibin-α protein mainly through hydrophobic bonds. Immunity tests revealed that the nanobody Nb-4 could effectively inhibit sheep inhibin A/B and could significantly improve the FSH level in sheep.

Conclusion

Four inhibin α-subunit-specific nanobodies with biological functions were successfully screened. To the best of our knowledge, this is a new reproductive immunomodulatory pathway of inhibin α-subunit, which may change the secretion of FSH in the ovary, thus changing the estrous cycle of organisms.

Single-domain antibodies as therapeutics for solid tumor treatment

Single-domain antibodies (sdAbs), initially identified in camelids or sharks and commonly referred to as nanobodies or VNARs, have emerged as a promising alternative to conventional therapeutic antibodies. These sdAbs have many superior physicochemical and pharmacological properties, including small size, good solubility and thermostability, easier accessible epitopes, and strong tissue penetration. However, the inherent challenges associated with the animal origin of sdAbs limit their clinical use. In recent years, various innovative humanization technologies, including complementarity-determining region (CDR) grafting or complete engineering of fully human sdAbs, have been developed to mitigate potential immunogenicity issues and enhance their compatibility. This review provides a comprehensive exploration of sdAbs, emphasizing their distinctive features and the progress in humanization methodologies. In addition, we provide an overview of the recent progress in developing drugs and therapeutic strategies based on sdAbs and their potential in solid tumor treatment, such as sdAb-drug conjugates, multispecific sdAbs, sdAb-based delivery systems, and sdAb-based cell therapy.

Sequence-based design and construction of synthetic nanobody library

Nanobody (Nb), the smallest antibody fragments known to bind antigens, is now widely applied to various studies, including protein structure analysis, bioassay, diagnosis, and biomedicine. The traditional approach to generating specific nanobodies involves animal immunization which is time-consuming and expensive. As the understanding of the antibody repertoire accumulation, the synthetic library, which is devoid of animals, has attracted attention widely in recent years. Here, we describe a synthetic phage display library (S-Library), designed based on the systematic analysis of the next-generation sequencing (NGS) of nanobody repertoire. The library consists of a single highly conserved scaffold (IGHV3S65*01-IGHJ4*01) and complementary determining regions of constrained diversity. The S-Library containing 2.19 × 108 independent clones was constructed by the one-step assembly and rapid electro-transformation. The S-Library was screened against various targets (Nb G8, fusion protein of Nb G8 and green fluorescent protein, bovine serum albumin, ovalbumin, and acetylcholinesterase). In comparison, a naïve library (N-Library) from the source of 13 healthy animals was constructed and screened against the same targets as the S-Library. Binders were isolated from both S-Library and N-Library. The dynamic affinity was evaluated by the biolayer interferometry. The data confirms that the feature of the Nb repertoire is conducive to reducing the complexity of library design, thus allowing the S-Library to be built on conventional reagents and primers.

Therapeutic nanobodies against SARS-CoV-2 and other pathogenic human coronaviruses

Nanobodies, single-domain antibodies derived from variable domain of camelid or shark heavy-chain antibodies, have unique properties with small size, strong binding affinity, easy construction in versatile formats, high neutralizing activity, protective efficacy, and manufactural capacity on a large-scale. Nanobodies have been arisen as an effective research tool for development of nanobiotechnologies with a variety of applications. Three highly pathogenic coronaviruses (CoVs), SARS-CoV-2, SARS-CoV, and MERS-CoV, have caused serious outbreaks or a global pandemic, and continue to post a threat to public health worldwide. The viral spike (S) protein and its cognate receptor-binding domain (RBD), which initiate viral entry and play a critical role in virus pathogenesis, are important therapeutic targets. This review describes pathogenic human CoVs, including viral structures and proteins, and S protein-mediated viral entry process. It also summarizes recent advances in development of nanobodies targeting these CoVs, focusing on those targeting the S protein and RBD. Finally, we discuss potential strategies to improve the efficacy of nanobodies against emerging SARS-CoV-2 variants and other CoVs with pandemic potential. It will provide important information for rational design and evaluation of therapeutic agents against emerging and reemerging pathogens.

NanoLAS: a comprehensive nanobody database with data integration, consolidation and application

Nanobodies, a unique subclass of antibodies first discovered in camelid animals, are composed solely of a single heavy chain's variable region. Their significantly reduced molecular weight, in comparison to conventional antibodies, confers numerous advantages in the treatment of various diseases. As research and applications involving nanobodies expand, the quantity of identified nanobodies is also rapidly growing. However, the existing antibody databases are deficient in type and coverage, failing to satisfy the comprehensive needs of researchers and thus impeding progress in nanobody research. In response to this, we have amalgamated data from multiple sources to successfully assemble a new and comprehensive nanobody database. This database has currently included the latest nanobody data and provides researchers with an excellent search and data display interface, thus facilitating the progression of nanobody research and their application in disease treatment. In summary, the newly constructed Nanobody Library and Archive System may significantly enhance the retrieval efficiency and application potential of nanobodies. We envision that Nanobody Library and Archive System will serve as an accessible, robust and efficient tool for nanobody research and development, propelling advancements in the field of biomedicine. Database URL: https://www.nanolas.cloud.

A Novel Anti-CD47 Nanobody Tetramer for Cancer Therapy

CD47 acts as a defense mechanism for tumor cells by sending a "don't eat me" signal via its bond with SIRPα. With CD47's overexpression linked to poor cancer outcomes, its pathway has become a target in cancer immunotherapy. Though monoclonal antibodies offer specificity, they have limitations like the large size and production costs. Nanobodies, due to their small size and unique properties, present a promising therapeutic alternative. In our study, a high-affinity anti-CD47 nanobody was engineered from an immunized alpaca. We isolated a specific VHH from the phage library, which has nanomolar affinity to SIRPα, and constructed a streptavidin-based tetramer. The efficacy of the nanobody and its derivative was evaluated using various assays. The new nanobody demonstrated higher affinity than the monoclonal anti-CD47 antibody, B6H12.2. The nanobody and its derivatives also stimulated substantial phagocytosis of tumor cell lines and induced apoptosis in U937 cells, a response confirmed in both in vitro and in vivo settings. Our results underscore the potential of the engineered anti-CD47 nanobody as a promising candidate for cancer immunotherapy. The derived nanobody could offer a more effective, cost-efficient alternative to conventional antibodies in disrupting the CD47-SIRPα axis, opening doors for its standalone or combinatorial therapeutic applications in oncology.

Specific Targeting of Zinc Transporter LIV-1 with Immunocytokine Containing Anti-LIV-1 VHH and Human IL-2 and Evaluation of its In vitro Antitumor Activity

BACKGROUND

Interleukin 2 (IL-2) is a vital cytokine in the induction of T and NK cell responses, the proliferation of CD8+ T cells, and the effective treatment of human cancers such as melanoma and renal cell carcinoma. However, widespread use of this cytokine is limited due to its short half-life, severe toxicity, lack of specific tumor targeting, and activation of Treg cells mediated by high-affinity interleukin-2 receptors.

OBJECTIVE

In this study, a tumor-targeting LIV-1 VHH-mutIL2 immunocytokine with reduced CD25 (α chain of the high-affinity IL-2 receptor) binding activity was developed to improve IL-2 half-life by decreasing its renal infiltration in comparison with wild and mutant IL-2 molecules.

METHODS

The recombinant immunocytokine was designed and expressed. The biological activity of the purified fusion protein was investigated in in vitro and in vivo experiments.

RESULTS

The fusion protein represented specific binding to MCF7 (the breast cancer cell line) and more efficient cytotoxicity than wild-type IL-2 and mutant IL-2. The PK parameters of the recombinant immunocytokine were also improved in comparison to the IL-2 molecules.

CONCLUSION

The observed results showed that LIV1-mIL2 immunocytokine could be considered as an effective agent in the LIV-1-targeted treatment of cancers due to its longer half-life and stronger cytotoxicity.

Ligand-based active targeting strategies for cancer theranostics

In the past decades, for the intermediate or advanced cancerous stages, preclinical and clinical applications of nanomedicines in cancer theranostics have been extensively studied. Nevertheless, decreased specificity and poor targeting efficiency with low target concentration of theranostic are the major drawbacks of nanomedicine in employing clinical substitution over conventional systemic therapy. Consequently, ligand decorated nanocarrier-mediated targeted drug delivery system can transcend the obstructions through their enhanced retention activity and increased permeability with effective targeting. The highly efficient and specific nanocarrier-mediated ligand-based active therapy is one of the novel and promising approaches for delivery of the therapeutics for different cancers in recent years to restrict various cancer growth in vivo without harming healthy cells. The article encapsulates the features of nanocarrier-mediated ligands in augmentation of active targeting approaches of various cancers and summarizes ligand-based targeted delivery systems in treatment of cancer as plausible theranostics.

Development of recombinant secondary antibody mimics (rSAMs) for immunoassays through genetic fusion of monomeric alkaline phosphatase with antibody binders

In conventional immunoassays, a secondary antibody is used to amplify the signal generated by the binding of the primary antibody to the target analyte. Due to concerns regarding animal use and cost-inefficiency of secondary antibody productions, there is a significant demand for the development of recombinant secondary antibody mimics (rSAMs). Here, we developed rSAMs using a signal-generating enzyme, monomeric alkaline phosphatase (mALP), and antibody-binders, including monomeric streptavidin (mSA2) and mouse IgG1- or rabbit IgG-binding nanobodies (MG1Nb or RNb). The mALP-MG1Nb, mALP-RNb, and mALP-mSA2 were genetically constructed and produced in large quantities using bacterial overexpression systems, which reduced manufacturing costs and time without the use of animals. Each rSAM exhibited high and selective binding to its respective primary antibody, generating linear band signals corresponding to the amounts of target analytes in western blots. The rSAMs also successfully generated sigmoidal signal curves that increased as the sample concentration increased. Moreover, they generated stronger signals than conventional ALP-conjugated secondary antibodies and SA, particularly in the medium to high sample concentration range, in both indirect and sandwich-type indirect ELISAs at the same sample concentration. The rSAMs we developed here may provide new insights to develop novel immunoassay-based analytical and diagnostic tools.

Single-domain antibodies applied as antiviral immunotherapeutics

Viral infections have been the cause of high mortality rates throughout different periods in history. Over the last two decades, outbreaks caused by zoonotic diseases and transmitted by arboviruses have had a significant impact on human health. The emergence of viral infections in different parts of the world encourages the search for new inputs to fight pathologies of viral origin. Antibodies represent the predominant class of new drugs developed in recent years and approved for the treatment of various human diseases, including cancer, autoimmune and infectious diseases. A promising group of antibodies are single-domain antibodies derived from camelid heavy chain immunoglobulins, or VHHs, are biomolecules with nanometric dimensions and unique pharmaceutical and biophysical properties that can be used in the diagnosis and immunotherapy of viral infections. For viral neutralization to occur, VHHs can act in different stages of the viral cycle, including the actual inhibition of infection, to hindering viral replication or assembly. This review article addresses advances involving the use of VHHs in therapeutic propositions aimed to battle different viruses that affect human health.

Shark IgNAR: The Next Broad Application Antibody in Clinical Diagnoses and Tumor Therapies?

Antibodies represent a relatively mature detection means and serve as therapeutic drug carriers in the clinical diagnosis and treatment of cancer-among which monoclonal antibodies (mAbs) currently occupy a dominant position. However, the emergence and development of small-molecule monodomain antibodies are inevitable due to the many limitations of mAbs, such as their large size, complex structure, and sensitivity to extreme temperature, and tumor microenvironments. Thus, since first discovered in Chondroid fish in 1995, IgNAR has become an alternative therapeutic strategy through which to replace monoclonal antibodies, thus entailing that this novel type of immunoglobulin has received wide attention with respect to clinical diagnoses and tumor therapies. The variable new antigen receptor (VNAR) of IgNAR provides an advantage for the development of new antitumor drugs due to its small size, high stability, high affinity, as well as other structural and functional characteristics. In that respect, a better understanding of the unique characteristics and therapeutic potential of IgNAR/VNAR in clinical and anti-tumor treatment is needed. This article reviews the advantages of its unique biochemical conditions and molecular structure for clinical diagnoses and novel anti-tumor drugs. At the same time, the main advantages of the existing conjugated drugs, which are based on single-domain antibodies, are introduced here, thereby providing new ideas and methods for the development of clinical diagnoses and anti-tumor therapies in the future.

Selection, identification and crystal structure of shark-derived single-domain antibodies against a green fluorescent protein

Shark variable domain of new antigen receptors (VNARs) are the smallest naturally occurring binding domains with properties of low complexity, small size, cytoplasmic expression, and ease of engineering. Green fluorescent protein (GFP) molecules have been analyzed in conventional microscopy, but their spectral characteristics preclude their use in techniques offering substantially higher resolution. Besides, the GFP molecules can be quenched in acidic environment, which makes it necessary to develop anti-GFP antibody to solve these problems. In view of the diverse applications of GFP and unique physicochemical features of VNAR, the present study aims to generate VNARs against GFP. Here, we identified 36 VNARs targeting eCGP123, an extremely stable GFP, by phage display from three immunized sharks. These VNARs bound to eCGP123 with affinity constant KD values ranging from 6.76 to 605 nM. Among them, two lead VNARs named aGFP-14 and aGFP-15 with nanomolar eCGP123-binding affinity were selected for in-depth characterization. aGFP-14 and aGFP-15 recognized similar epitopes on eCGP123. X-ray crystallography studies clarified the mechanism by which aGFP14 interacts with eCGP123. aGFP-14 also showed cross-reaction with EGFP, with KD values of 47.2 nM. Finally, immunostaining analyses demonstrated that aGFP-14 was able to bind effectively to the EGFP expressed in both cultured cells and mouse brain tissues, and can be used as a fluorescence amplifier for EGFP. Our research demonstrates a feasible idea for the screening and production of shark-derived VNARs. The two high-affinity VNARs developed in the study contribute to the diversity of GFP sdAbs and may enhance the applications of GFP.

Mucosal nanobody IgA as inhalable and affordable prophylactic and therapeutic treatment against SARS-CoV-2 and emerging variants

Anti-COVID antibody therapeutics have been developed but not widely used due to their high cost and escape of neutralization from the emerging variants. Here, we describe the development of VHH-IgA1.1, a nanobody IgA fusion molecule as an inhalable, affordable and less invasive prophylactic and therapeutic treatment against SARS-CoV-2 Omicron variants. VHH-IgA1.1 recognizes a conserved epitope of SARS-CoV-2 spike protein Receptor Binding Domain (RBD) and potently neutralizes major global SARS-CoV-2 variants of concern (VOC) including the Omicron variant and its sub lineages BA.1.1, BA.2 and BA.2.12.1. VHH-IgA1.1 is also much more potent against Omicron variants as compared to an IgG Fc fusion construct, demonstrating the importance of IgA mediated mucosal protection for Omicron infection. Intranasal administration of VHH-IgA1.1 prior to or after challenge conferred significant protection from severe respiratory disease in K18-ACE2 transgenic mice infected with SARS-CoV-2 VOC. More importantly, for cost-effective production, VHH-IgA1.1 produced in Pichia pastoris had comparable potency to mammalian produced antibodies. Our study demonstrates that intranasal administration of affordably produced VHH-IgA fusion protein provides effective mucosal immunity against infection of SARS-CoV-2 including emerging variants.

Application of recombinant antibodies for treatment of Clostridioides difficile infection: Current status and future perspective

Clostridioides difficile (C. difficile), known as the major cause of antibiotic-associated diarrhea, is regarded as one of the most common healthcare-associated bacterial infections worldwide. Due to the emergence of hypervirulent strains, development of new therapeutic methods for C. difficile infection (CDI) has become crucially important. In this context, antibodies have been introduced as valuable tools in the research and clinical environments, as far as the effectiveness of antibody therapy for CDI was reported in several clinical investigations. Hence, production of high-performance antibodies for treatment of CDI would be precious. Traditional approaches of antibody generation are based on hybridoma technology. Today, application of in vitro technologies for generating recombinant antibodies, like phage display, is considered as an appropriate alternative to hybridoma technology. These techniques can circumvent the limitations of the immune system and they can be exploited for production of antibodies against different types of biomolecules in particular active toxins. Additionally, DNA encoding antibodies is directly accessible in in vitro technologies, which enables the application of antibody engineering in order to increase their sensitivity and specificity. Here, we review the application of antibodies for CDI treatment with an emphasis on recombinant fragment antibodies. Also, this review highlights the current and future prospects of the aforementioned approaches for antibody-mediated therapy of CDI.

The mosaic puzzle of the therapeutic monoclonal antibodies and antibody fragments - A modular transition from full-length immunoglobulins to antibody mimetics

The use of monoclonal antibodies represents an important and efficient diagnostic and therapeutic tool in disease management and modern science but remains limited by several factors including the uneven distribution in diseased tissues as well as undesired activation of side immune reactions. Major scientific advancements including Recombinant DNA Technology, Hybridoma Technology, and Polymerase Chain Reaction have considerably impacted the use of monoclonal antibodies providing technical and effective solutions to overcome the shortcomings encountered with conventional antibodies. Initially, the introduction of antibody fragments allowed a more uniform and deeper penetration of the targeted tissue and reduced unwanted activation of Fc-mediated immune reactions. On another level, the immunogenicity of murine-derived antibodies was overcome by humanizing their encoding genes with specific sequences of human origin andtransgenic mice able to synthesize fully human antibodies were successfully created. Moreover, the advancement of genetic engineering techniques supported by the modular structure of antibody coding genes paved the way for the development of a new generation of antibody fragments with a wide spectrum of monospecific and bispecific agents. These later could be monovalent, bivalent, or multivalent, and either expressed as a single chain, assembled in multimeric forms or stringed in tandem. This has conferred improved affinity, stability, and solubility to antibody targetting. Lately, a new array of monoclonal antibody fragments was introduced with the engineering of nanobody and antibody mimetics as non-immunoglobulin-derived fragments with promising diagnostic and therapeutic applications. In this review, we decipher the molecular basis of monoclonal antibody engineering with a detailed screening of the antibody derivatives that provides new perspectives to expand the use of monoclonal fragments into previously unexplored fields.

Structural insights into the non-inhibitory mechanism of the anti-EGFR EgB4 nanobody

Background

The epidermal growth factor receptor (EGFR) is involved in various developmental processes, and alterations of its extracellular segment are associated with several types of cancers, in particular glioblastoma multiforme (GBM). The EGFR extracellular region is therefore a primary target for therapeutic agents, such as monoclonal antibodies and variable domains of heavy chain antibodies (VHH), also called nanobodies. Nanobodies have been previously shown to bind to EGFR, and to inhibit ligand-mediated EGFR activation.

Results

Here we present the X-ray crystal structures of the EgB4 nanobody, alone (to 1.48 Å resolution) and bound to the full extracellular EGFR-EGF complex in its active conformation (to 6.0 Å resolution). We show that EgB4 binds to a new epitope located on EGFR domains I and II, and we describe the molecular mechanism by which EgB4 plays a non-inhibitory role in EGFR signaling.

Conclusion

This work provides the structural basis for the application of EgB4 as a tool for research, for targeted therapy, or as a biomarker to locate EGFR-associated tumors, all without affecting EGFR activation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12860-022-00412-x.

A comprehensive comparison between camelid nanobodies and single chain variable fragments

By the emergence of recombinant DNA technology, many antibody fragments have been developed devoid of undesired properties of natural immunoglobulins. Among them, camelid heavy-chain variable domains (VHHs) and single-chain variable fragments (scFvs) are the most favored ones. While scFv is used widely in various applications, camelid antibodies (VHHs) can serve as an alternative because of their superior chemical and physical properties such as higher solubility, stability, smaller size, and lower production cost. Here, these two counterparts are compared in structure and properties to identify which one is more suitable for each of their various therapeutic, diagnosis, and research applications.

A new PD-1-specific nanobody enhances the antitumor activity of T-cells in synergy with dendritic cell vaccine

Despite the many successes and opportunities presented by PD-1 blockade in cancer therapies, anti-PD-1 monoclonal antibodies still face multiple challenges. Herein we report a strategy based on a nanobody (Nb) to circumvent these obstacles. A new PD-1-blocking Nb (PD-1 Nb20) in combination with tumor-specific dendritic cell (DC)/tumor-fusion cell (FC) vaccine that aims to improve the activation, proliferation, cytokine secretion, and tumor cell cytotoxicity of CD8⁺ T-cells. This combination was found to effectively enhance the in vitro cytotoxicity of CD8⁺ T-cells to kill human non-small cell lung cancer (NSCLC) HCC827 cells, hepatocellular carcinoma (HCC) HepG2 cells, and tongue squamous cell carcinoma (TSCC) Tca8113 cells. Moreover, CD8⁺ T-cells pre-treated with PD-1 Nb20 and tumor-specific DC/tumor-FCs significantly suppressed the growth of NSCLC-, HCC- and TSCC-derived xenograft tumors and prolonged the survival of tumor-bearing mice, through promoting T-cell infiltration to kill tumor cells and inhibiting tumor angiogenesis. These data demonstrate that PD-1 Nb20 in synergy with DC/tumor-FC vaccine augment the broad spectrum of antitumor activity of CD8⁺ T-cells, providing an alternative and promising immunotherapeutic strategy for tumor patients who are T-cell-dysfunctional or not sensitive to anti-PD-1 therapy.

Study review of camelid and shark antibodies for biomedical and biotechnological applications

The antibodies of camelids and sharks are about one–half of the conventional ones while regular antibodies have four protein chains: two light and two heavy, these small antibodies studied have just two heavy chains; they lack a light chain. In recent years, nanobodies have been the focus of attention because they can recognize epitopes that are usually not antigenic (hidden) for conventional antibodies. On the clinical side, researchers are testing nanobodies (Nbs) in the fight against diseases and disease diagnosis. Nanobodies also are attractive because they can prevent protein aggregation and clear the already existing aggregates. Furthermore, new treatments using these Nbs can neutralize the severe acute respiratory syndrome coronavirus (SARS-CoV-2) for preventing COVID-19. In this review, we sum up recent findings of the proposed nanobodies for their potential application.

Nanobodies Enhancing Cancer Visualization, Diagnosis and Therapeutics

Worldwide, cancer is a serious health concern due to the increasing rates of incidence and mortality. Conventional cancer imaging, diagnosis and treatment practices continue to substantially contribute to the fight against cancer. However, these practices do have some risks, adverse effects and limitations, which can affect patient outcomes. Although antibodies have been developed, successfully used and proven beneficial in various oncology practices, the use of antibodies also comes with certain challenges and limitations (large in size, poor tumor penetration, high immunogenicity and a long half-life). Therefore, it is vital to develop new ways to visualize, diagnose and treat cancer. Nanobodies are novel antigen-binding fragments that possess many advantageous properties (small in size, low immunogenicity and a short half-life). Thus, the use of nanobodies in cancer practices may overcome the challenges experienced with using traditional antibodies. In this review, we discuss (1) the challenges with antibody usage and the superior qualities of nanobodies; (2) the use of antibodies and nanobodies in cancer imaging, diagnosis, drug delivery and therapy (surgery, radiotherapy, chemotherapy and immunotherapy); and (3) the potential improvements in oncology practices due to the use of nanobodies as compared to antibodies.

Immunotoxins and nanobody-based immunotoxins: review and update

Immunotoxins (ITs) are protein-based drugs that compose of targeting and cytotoxic moieties. After binding the IT to the specific cell-surface antigen, the IT internalises into the target cell and kills it. Targeting and cytotoxic moieties usually include monoclonal antibodies and protein toxins with bacterial or plant origin, respectively. ITs have been successful in haematologic malignancies treatment. However, ITs penetrate poorly into solid tumours because of their large size. Use of camelid antibody fragments known as nanobodies (Nbs) as a targeting moiety may overcome this problem. Nbs are the smallest fragment of antibodies with excellent tumour tissue penetration. The ability to recognise cryptic (immuno-evasive) target antigens, low immunogenicity, and high-affinity are other fundamental characteristics of Nbs that make them suitable candidates in targeted therapy. Here, we reviewed and discussed the structure and function of ITs, Nbs, and nanobody-based ITs. To gain sound insight into the issue at hand, we focussed on nanobody-based ITs.

Development and assessment of the efficacy and safety of human lung-targeting liposomal methylprednisolone crosslinked with nanobody

Glucocorticoid (GC) hormone has been commonly used to treat systemic inflammation and immune disorders. However, the side effects associated with long-term use of high-dose GC hormone limit its clinical application seriously. GC hormone that can specifically target the lung might decrease the effective dosage and thus reduce GC-associated side effects. In this study, we successfully prepared human lung-targeting liposomal methylprednisolone crosslinked with nanobody (MPS-NSSLs-SPANb). Our findings indicate that MPS-NSSLs-SPANb may reduce the effective therapeutic dosage of MPS, achieve better efficacy, and reduce GC-associated side effects. In addition, MPS-NSSLs-SPANb showed higher efficacy and lower toxicity than conventional MPS.

Camelid Single-Domain Antibodies for the Development of Potent Diagnosis Platforms

The distinct biophysical and pharmaceutical properties of camelid single-domain antibodies, referred to as VHHs or nanobodies, are associated with their nanometric dimensions, elevated stability, and antigen recognition capacity. These biomolecules can circumvent a number of diagnostic system limitations, especially those related to the size and stability of conventional immunoglobulins currently used in enzyme-linked immunosorbent assays and point-of-care, electrochemical, and imaging assays. In these formats, VHHs are directionally conjugated to different molecules, such as metallic nanoparticles, small peptides, and radioisotopes, which demonstrates their comprehensive versatility. Thus, the application of VHHs in diagnostic systems range from the identification of cancer cells to the detection of degenerative disease biomarkers, viral antigens, bacterial toxins, and insecticides. The improvements of sensitivity and specificity are among the central benefits resulting from the use of VHHs, which are indispensable parameters for high-quality diagnostics. Therefore, this review highlights the main biotechnological advances related to camelid single-domain antibodies and their use in in vitro and in vivo diagnostic approaches for human health.

VHH212 nanobody targeting the hypoxia-inducible factor 1α suppresses angiogenesis and potentiates gemcitabine therapy in pancreatic cancer in vivo

OBJECTIVE

We aimed to develop a novel anti-HIF-1α intrabody to decrease gemcitabine resistance in pancreatic cancer patients.

METHODS

Surface plasmon resonance and glutathione S-transferase pull-down assays were conducted to identify the binding affinity and specificity of anti-HIF-1α VHH212 [a single-domain antibody (nanobody)]. Molecular dynamics simulation was used to determine the protein-protein interactions between hypoxia-inducible factor-1α (HIF-1α) and VHH212. The real-time polymerase chain reaction (PCR) and Western blot analyses were performed to identify the expressions of HIF-1α and VEGF-A in pancreatic ductal adenocarcinoma cell lines. The efficiency of the VHH212 nanobody in inhibiting the HIF-1 signaling pathway was measured using a dual-luciferase reporter assay. Finally, a PANC-1 xenograft model was developed to evaluate the anti-tumor efficiency of combined treatment. Immunohistochemistry analysis was conducted to detect the expressions of HIF-1α and VEGF-A in tumor tissues.

RESULTS

VHH212 was stably expressed in tumor cells with low cytotoxicity, high affinity, specific subcellular localization, and neutralization of HIF-1α in the cytoplasm or nucleus. The binding affinity between VHH212 and the HIF-1α PAS-B domain was 42.7 nM. Intrabody competitive inhibition of the HIF-1α heterodimer with an aryl hydrocarbon receptor nuclear translocator was used to inhibit the HIF-1/VEGF pathway in vitro. Compared with single agent gemcitabine, co-treatment with gemcitabine and a VHH212-encoding adenovirus significantly suppressed tumor growth in the xenograft model with 80.44% tumor inhibition.

CONCLUSIONS

We developed an anti-HIF-1α nanobody and showed the function of VHH212 in a preclinical murine model of PANC-1 pancreatic cancer. The combination of VHH212 and gemcitabine significantly inhibited tumor development. These results suggested that combined use of anti-HIF-1α nanobodies with first-line treatment may in the future be an effective treatment for pancreatic cancer.

Nanobody: A Small Antibody with Big Implications for Tumor Therapeutic Strategy

The development of monoclonal antibody treatments for successful tumor-targeted therapies took several decades. However, the efficacy of antibody-based therapy is still confined and desperately needs further improvement. Nanobodies are the recombinant variable domains of heavy-chain-only antibodies, with many unique properties such as small size (~15kDa), excellent solubility, superior stability, ease of manufacture, quick clearance from blood, and deep tissue penetration, which gain increasing acceptance as therapeutical tools and are considered also as building blocks for chimeric antigen receptors as well as for targeted drug delivery. Thus, one of the promising novel developments that may address the deficiency of monoclonal antibody-based therapies is the utilization of nanobodies. This article provides readers the significant factors that the structural and biochemical properties of nanobodies and the research progress on nanobodies in the fields of tumor treatment, as well as their application prospect.

Radiolabeled nanobodies for tumor targeting: From bioengineering to imaging and therapy

So far, numerous molecules and biomolecules have been evaluated for tumor targeting purposes for radionuclide-based imaging and therapy modalities. Due to the high affinity and specificity against tumor antigens, monoclonal antibodies are appropriate candidates for tumor targeting. However, their large size prevents their comprehensive application in radionuclide-based tumor imaging or therapy, since it leads to their low tumor penetration, low blood clearance, and thus inappropriate tumor-to-background ratio. Nowadays, the variable domain of heavy-chain antibodies from the Camelidae family, known as nanobodies (Nbs), turn into exciting candidates for medical research. Considering several innate advantages of these new tumor-targeting agents, including excellent affinity and specificity toward antigen, high solubility, high stability, fast washout from blood, convenient production, ease of selection, and low immunogenicity, it assumes that they may overcome generic problems of monoclonal antibodies, their fragments, and other vectors used for tumor imaging/therapy. After three decades of Nbs discovery, the increasing number of their preclinical and clinical investigations, which have led to outstanding results, confirm their application for tumor targeting purposes. This review describes Nbs characteristics, the diagnostic and therapeutic application of their radioconjugates, and their recent advances.

Generation of a nanobody against HER2 tyrosine kinase using phage display library screening for HER2-positive breast cancer therapy development

Human epidermal growth factor receptor 2 (HER2) protein overexpression is found in ~30% of invasive breast carcinomas and in a high proportion of noninvasive ductal carcinomas in situ. Targeted cancer therapy is based on monoclonal antibodies and kinase inhibitors and reflects a new era of cancer therapy. However, delivery to tumor cells in vivo is hampered by the large size (150 kDa) of conventional antibodies. Furthermore, there are many disadvantages with the current anti-HER2 drug, including drug resistance and adverse effects. Nanobodies (15 kDa), single-domain antibody (sdAb) fragments, can overcome these limitations. This study produced the recombinant sdAb against the HER2-tyrosine kinase (HER2-TK) domain using phage display technology. Three specific anti-HER2-TK sdAbs were selected for further characterization. Hallmark VHH residue identification and amino acid sequence analysis revealed that clone numbers 4 and 22 were VH antibodies, whereas clone number 17 was a VH H antibody (nanobody). The half-maximal inhibitory concentration of VHH17 exhibited significantly greater HER2 kinase-inhibition activity than the other clones. Consistent with these results, several charges and polar residues of the HER2-TK activation loop that were predicted based on mimotope analysis also appeared in the docking result and interacted via the CDR1, CDR2 and CDR3 loops of VHH17. Furthermore, the cell-penetrable VHH17 (R9 VHH17) showed cell-penetrability and significantly decreased HER2-positive cancer cell viability. Thus, the VH H17 could be developed as an effective therapeutic agent to treat HER2-positive breast cancer.

A novel intracellular nanobody against HPV16 E6 oncoprotein

Cervical cancer occurs as a result of the persistent infection of high-risk human papillomavirus (HPV). HPV16 oncoproteins E6 and E7 exert different and concerted pro-tumor actions in cell transformation and malignance maintenance in various m echanisms. Nanobody expressed as "intracellular antibodies" (intrabodies) can target intracellular antigens to hamper their function efficaciously and specifically. In this work, phage-display approach was employed to select the high affinity HPV16 E6-specific nanobody, nanobody Nb9 against HPV16 E6 was selected. Nb9 has high affinity (Kaff =6.3 × 10⁸ M^-) and can specifically bind endogenous HPV16 E6 protein in HPV16 positive CaSki and SiHa cells. In Nb9 overexpressed SiHa and CaSki cells, nucleus localization of HPV16 E6 was inhibited, p53 inactivation was prevented and increased apoptosis was observed. Moreover, tumor growth was inhibited in mouse xenograft model. Taken together, our results suggested that nanobody Nb9 could be a useful inhibitor for HPV16 E6 function and particularly appropriate for the treatment of HPV-associated disease.

A nanobody-horseradish peroxidase fusion protein-based competitive ELISA for rapid detection of antibodies against porcine circovirus type 2

Background

The widespread popularity of porcine circovirus type 2(PCV2) has seriously affected the healthy development of the pig industry and caused huge economic losses worldwide. A rapid and reliable method is required for epidemiological investigation and evaluating the effect of immunization. However, the current methods for PCV2 antibody detection are time-consuming or very expensive and rarely meet the requirements for clinical application. we have constructed the platform for expressing the nanobody(Nb)‑horseradish peroxidase(HRP) fusion protein as an ultrasensitive probe to detect antibodies against the Newcastle disease virus(NDV), previously. In the present work, an Nb-HRP fusion protein-based competitive ELISA(cELISA) for rapid and simple detection antibodies against PCV2 was developed using this platform to detect anti-PCV2 antibodies in clinical porcine serum.

Results

Using phage display technology, 19 anti-PCV2-Cap protein nanobodies were screened from a PCV2-Cap protein immunized Bactrian camel. With the platform, the PCV2-Nb15‑HRP fusion protein was then produced and used as a sensitive reagent for developing a cELISA to detect anti‑PCV2 antibodies. The cut‑off value of the cELISA is 20.72 %. Three hundreds and sixty porcine serum samples were tested by both newly developed cELISA and commercial kits. The sensitivity and specificity were 99.68 % and 95.92 %, respectively. The coincidence rate of the two methods was 99.17 %. When detecting 620 clinical porcine serum samples, a good consistent (kappa value = 0.954) was found between the results of the cELISA and those of commercial kits.

Conclusions

In brief, the newly developed cELISA based PCV2-Nb15‑HRP fusion protein is a rapid, low-cost, reliable and useful nanobody-based tool for the serological evaluation of current PCV2 vaccine efficacy and the indirect diagnosis of PCV2 infection.

Nanobodies: The "Magic Bullets" in therapeutics, drug delivery and diagnostics

Antibodies represent a well-established class of clinical diagnostics for medical applications as well as essential research and biotechnological tools. Although both polyclonal and monoclonal antibodies are indispensable reagents in basic research and diagnostics but both of them have their limitations. Hence, there is urgent need to develop strategies aimed at production of alternative scaffolds and recombinant antibodies of smaller dimensions that could be easily produced, selected and manipulated. Unlike conventional antibodies, members of Camelidae and sharks produce antibodies composed only of heavy chains with small size, high solubility, thermal stability, refolding capacity and good tissue penetration in vivo. The discovery of these naturally occurring antibodies having only heavy-chain in Camelidae family and their further development into small recombinant nanobodies represents an attractive alternative in drug delivery, diagnostics and imaging. Nanobody derivatives are soluble, stable, versatile, have unique refolding capacities, reduced aggregation tendencies and high-target binding capabilities. They can be genetically customized to target enzymes, transmembrane proteins or molecular interactions. Their ability to recognize recessed antigenic sites has been attributed to their smaller size and the ability of the extended CDR3 loop to quickly penetrate into such epitopes. With the advent of molecular engineering and phage display technology, they can be of potential use in molecular imaging, drug delivery and therapeutics for several major diseases. In this review we present the recent advances in nanobodies for modulating immune functions, for targeting cancers, viruses, toxins and microbes as well as their utility as diagnostic and biosensor tools.

Contribution of Intrinsic Fluorescence to the Design of a New 3D-Printed Implant for Releasing SDABS

Single-domain antibodies (sdAbs) offer great features such as increased stability but are hampered by a limited serum half-life. Many strategies have been developed to improve the sdAb half-life, such as protein engineering and controlled release systems (CRS). In our study, we designed a new product that combined a hydrogel with a 3D-printed implant. The results demonstrate the implant’s ability to sustain sdAb release up to 13 days through a reduced initial burst release followed by a continuous release. Furthermore, formulation screening helped to identify the best sdAb formulation conditions and improved our understanding of our CRS. Through the screening step, we gained knowledge about the influence of the choice of polymer and about potential interactions between the sdAb and the polymer. To conclude, this feasibility study confirmed the ability of our CRS to extend sdAb release and established the fundamental role of formulation screening for maximizing knowledge about our CRS.

A Novel Nanobody Directed against Ovine Myostatin to Enhance Muscle Growth in Mouse

Simple Summary

Myostatin (MSTN) is a negative regulator of myogenesis, and various strategies have been used to improve livestock production by inhibiting MSTN. In this study, we developed a single-variable domain of the heavy chain antibody-recombinant MSTN nanobody (RMN) against MSTN. The selected RMN was expressed, purified, and assessed for its cytotoxicity, affinity, specificity, and the ability to inhibit MSTN. The results demonstrated that RMN could specifically detect and bind MSTN, further inhibit myostatin activity, as well as enhance muscle growth in mice.

Abstract

Myostatin (MSTN) is a member of the transforming growth factor beta superfamily and is a negative regulator of myogenesis. It has been shown to function by controlling the proliferation of myoblasts. MSTN inhibition is considered as a promising treatment for promoting animal growth in livestock. Nanobodies, a special antibody discovered in camel, have arisen as an alternative to conventional antibodies and have shown great potential when used as tools in different biotechnology fields, such as diagnostics and therapy. In this study, we examined the effect of MSTN inhibition by RMN on the muscle growth of mice. The results showed that RMN could specifically detect and bind MSTN, as well as inhibit MSTN activity. A significant increase in skeletal muscle mass was observed after intramuscular injection of RMN into mice. Enhanced muscle growth occurred because of myofiber hypertrophy. These results offer a promising approach to enhance muscle growth that warrants further investigation in domestic animals.

<p>Recent Advances of Magnetic Nanomaterials in the Field of Oncology</p>

Nanomagnetic devices, such as nano-field effect transistor biosensors and radio frequency magnetic induction therapies, came into being with the development of medical nanomaterials. The application of nanomagnetic materials in the treatment of cancers is rapidly becoming increasingly important because of its ability to target therapy and diagnose early. In this review, an untechnical overview of the fundamental of magnetism in nanomaterials and an illustration of how these materials are applied are presented. The applications of nano-field effect transistor biosensors for the detection of tumor biomarker nanomaterials in the therapy and diagnosis of cancers and nanomagnetic materials are summarized in this paper. A systemic summary of the use of nanomagnetic materials and nano-filed effect transistor biosensors for the treatment and diagnosis of tumors is also provided in the review.

Cysteine Residues in Helicobacter pylori Adhesin HopQ are Required for CEACAM-HopQ Interaction and Subsequent CagA Translocation

Attachment to the host gastric mucosa is a key step in Helicobacter pylori infection. Recently, a novel adhesin, HopQ, was shown to bind distinct host CEACAM proteins—an interaction that was found to be essential for the translocation of CagA, a key virulence factor of H. pylori. The HopQ–CEACAM1 co-crystal structure revealed a binding mode dependent on loops in HopQ that are clasped by disulfide bonds. In this study, we investigated the importance of these cysteine residues for CEACAM1 engagement by H. pylori. We observed a loss of CEACAM1 binding and CagA translocation upon disruption of the disulfide bond in loop CL1 (connecting C103 to C132 in HopQ). Deletion of the Dsb-like oxidoreductase HP0231 did not affect cell surface expression of HopQ or alter the interaction of H. pylori with target cells. Although HP0231 deletion was previously described to impede CagA translocation, our results indicate that this occurs through a HopQ-independent mechanism. Together, our results open up new avenues to therapeutically target the HopQ–CEACAM1 interaction and reduce the burden of pathogenic H. pylori.

A high affinity nanobody against endothelin receptor type B: a new approach to the treatment of melanoma

The aim of the study was to produce a single-domain antibody (nanobody) specific for endothelin receptor type B (EDNRB) which has high expression in melanoma. Cultured human melanoma cells were used as antigens to immunize alpacas. After antibody generation was verified in alpaca serum, total RNA was extracted from alpaca lymphocytes and the target V_HH fragment was amplified by two-step PCR, cloned in the pCANTAB5E phagemid vector, and used to transform Escherichia coli TG1 cells to obtain a phage-display nanobody library, which was enriched by panning. The results indicated successful construction of a phage-display anti-human melanoma A375 nanobodies library with a size of 1.2 × 10⁸/ml and insertion rate of 80%. After screening, eight positive clones of anti-EDNRB nanobodies were used to infect E. coli HB2151 for production of soluble nanobodies, which were identified by ELISA. Finally, we obtained a high-affinity anti-EDNRB nanobody, which consisted of 119 amino acids (molecular weight: 12.97 kDa) with 22 amino acids in CDR3 and had good affinity in vitro. The results suggest that the nanobody may be potentially used for the treatment of human melanoma.

Selection and Characterization of CSFV-Specific Single-Domain Antibodies and Their Application along with Immunomagnetic Nanobeads and Quantum Dots

Outbreak of classical swine fever (CSF) results in high mortality and thus causes severe economic losses in the swine industry. Single-domain antibody (sdAb) is the smallest antigen-binding molecule derived from camelid heavy-chain antibodies and has the potential to be used as a molecular probe for detection of CSF virus (CSFV). In this study, two sdAb fragments against the E2 antigen of CSFV were obtained, expressed in vitro. The functional characteristics analysis indicated that the recombinant sdAbE2-1 and sdAbE2-2 have excellent binding activity, specificity, and high affinity with equilibrium constant value of 3.34 × 10⁻⁷ and 1.35 × 10⁻⁸ M to E2 protein. Then, sdAbE2s were conjugated with quantum dots (QD)/AF488 to synthesize two molecular probes for imaging CSFV distribution in cells. The sdAbE2-1 was also labeled with carboxyl-magnetic beads to construct immunomagnetic nanobeads (IMNBs) able to capture CSFV virions and recombinant E2 protein. QD/AF455-sdAbE2s probes colocalised with CSFV virions in swine testis cells, and IMNBs were used as a detection template and proved to bind specifically with CSFV virions and E2 protein. The selected sdAb fragments and sdAb-based molecular probes may be used for the rapid identification of CSFV during field outbreaks and for research on CSFV and host interactions.

Nanobodies in Human Infections: Prevention, Detection, and Treatment

Despite the existence of vaccination, antibiotic therapy, and antibody therapies, infectious diseases still remain as one of the biggest challenges to human health all over the world. Among the different methods for treatment and prevention of infectious diseases, antibodies are well known but poorly developed. There is a new subclass of antibodies calledheavy-chain antibodies that belong to the IgG isotype. However, they are low in molecular weight and lost the first constant domain (CH1). Their single-domain antigen-binding fragments, identified as nanobodies, have unique characteristics, which make them superior in comparison with the conventional antibodies. Low molecular weight and small size, high stability and solubility, ease of expression, good tissue penetration, and low-cost production make nanobodies an appropriate alternative to use against infectious disease. In this research, we review the properties of nanobodies and their potential applications in controlling human infections and inflammations.

Evaluation of Laboratory Application of Camelid Sera Containing Heavy-Chain Polyclonal Antibody Against Recombinant Cytotoxic T-Lymphocyte-Associated Protein-4

Cytotoxic T-lymphocyte-associated protein-4 (CTLA-4) is a critical negative immunomodulatory receptor that is normally expressed in activated T cells and noticeably, in many cancerous cells. Indeed, molecular detection of CTLA-4 protein is crucial in basic research. In this work, the extracellular domain of the human CTLA-4 (hCTLA-4) protein was cloned, expressed, and purified. Subsequently, this protein was used as an antigen for camel (Camelus dromedarius) immunization to obtain polyclonal camelid sera against this protein. Furthermore, we evaluated the benefits of applying camelid hyperimmune sera containing heavy-chain antibodies in different antibody-based techniques. Our results indicated that hCTLA-4 protein was successfully expressed in the prokaryotic system. The polyclonal antibody (pAb) that raised against recombinant hCTLA-4 protein was able to detect the CTLA-4 protein in antibody-based techniques, such as enzyme-linked immunosorbent assay, western blotting, flow cytometry and immunohistochemistry (IHC) staining. This study shows that, due to the advantages such as multi-epitope-binding ability, camelid pAbs are potent to efficiently apply for molecular detection of CTLA-4 receptors in fundamental antibody-based researches such as IHC.

A novel intracellularly expressed NS5B-specific nanobody suppresses bovine viral diarrhea virus replication

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BVDV NS5B-specific nanobodies were identified.

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NS5B-specific nanobody Nb1 suppresses BVDV infection and replication.

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Nb1 interacts with NS5B protein during BVDV infection.

Bovine viral diarrhea virus (BVDV) infection causes significant economic losses to the cattle industry worldwide and still represents a huge pressure on agricultural production. Thus, the development of novel anti-BVDV strategies are urgently needed. The nonstructural protein 5 (NS5B) of BVDV is essential for viral replication. Further, the camel single-domain antibody (nanobody) represents a promising antiviral approach with the advantages of small size, stable structure, high specificity and solubility, and the recognition of specific epitopes. However, no NS5B-specific nanobodies against BVDV have been reported. In this study, NS5B-specific nanobodies were isolated from a phage display library of variable domains of Camellidae heavy chain-only antibodies (VHHs). Further, an MDBK cell line stably expressing Nb1 was established to explore antiviral activity. Results showed that Nb1 could markedly suppress BVDV replication and interact with the BVDV NS5B protein. This suggests that nanobodies have potential for the development of novel antiviral drugs against BVDV infection.

Homology Modeling-Based in Silico Affinity Maturation Improves the Affinity of a Nanobody

Affinity maturation and rational design have a raised importance in the application of nanobody (VHH), and its unique structure guaranteed these processes quickly done in vitro. An anti-CD47 nanobody, Nb02, was screened via a synthetic phage display library with 278 nM of K_D value. In this study, a new strategy based on homology modeling and Rational Mutation Hotspots Design Protocol (RMHDP) was presented for building a fast and efficient platform for nanobody affinity maturation. A three-dimensional analytical structural model of Nb02 was constructed and then docked with the antigen, the CD47 extracellular domain (CD47^ext). Mutants with high binding affinity are predicted by the scoring of nanobody-antigen complexes based on molecular dynamics trajectories and simulation. Ultimately, an improved mutant with an 87.4-fold affinity (3.2 nM) and 7.36 °C higher thermal stability was obtained. These findings might contribute to computational affinity maturation of nanobodies via homology modeling using the recent advancements in computational power. The add-in of aromatic residues which formed aromatic-aromatic interaction plays a pivotal role in affinity and thermostability improvement. In a word, the methods used in this study might provide a reference for rapid and efficient in vitro affinity maturation of nanobodies.

How can monoclonal antibodies be harnessed against neglected tropical diseases and other infectious diseases?

Introduction: Monoclonal antibody-based therapies now represent the single-largest class of molecules undergoing clinical investigation. Although a handful of different monoclonal antibodies have been clinically approved for bacterial and viral indications, including rabies, therapies based on monoclonal antibodies are yet to fully enter the fields of neglected tropical diseases and other infectious diseases. Areas covered: This review presents the current state-of-the-art in the development and use of monoclonal antibodies against neglected tropical diseases and other infectious diseases, including viral, bacterial, and parasitic infections, as well as envenomings by animal bites and stings. Additionally, a short section on mushroom poisonings is included. Key challenges for developing antibody-based therapeutics are discussed for each of these fields. Expert opinion: Neglected tropical diseases and other infectious diseases represent a golden opportunity for academics and technology developers for advancing our scientific capabilities within the understanding and design of antibody cross-reactivity, use of oligoclonal antibody mixtures for multi-target neutralization, novel immunization methodologies, targeting of evasive pathogens, and development of fundamentally novel therapeutic mechanisms of action. Furthermore, a huge humanitarian and societal impact is to gain by exploiting antibody technologies for the development of biotherapies against diseases, for which current treatment options are suboptimal or non-existent.

Horizons of nanotechnology applications in female specific cancers

Female-specific cancers are the most common cancers in women worldwide. Early detection methods remain unavailable for most of these cancers, signifying that most of them are diagnosed at later stages. Furthermore, current treatment options for most female-specific cancers are surgery, radiation and chemotherapy. Although important milestones in molecularly targeted approaches have been achieved lately, current therapeutic strategies for female-specific cancers remain limited, ineffective and plagued by the emergence of chemoresistance, which aggravates prognosis. Recently, the application of nanotechnology to the medical field has allowed the development of novel nano-based approaches for the management and treatment of cancers, including female-specific cancers. These approaches promise to improve patient survival rates by reducing side effects, enabling selective delivery of drugs to tumor tissues and enhancing the uptake of therapeutic compounds, thus increasing anti-tumor activity. In this review, we focus on the application of nano-based technologies to the design of novel and innovative diagnostic and therapeutic strategies in the context of female-specific cancers, highlighting their potential uses and limitations.

Development of an immunoassay for the detection of carbaryl in cereals based on a camelid variable heavy-chain antibody domain

BACKGROUND

The variable domain of camelid heavy-chain antibodies (VHH) is increasingly being adapted to detect small molecules in various matrices. The insecticide carbaryl is widely used in agriculture while its residues have posed a threat to food safety and human health.

RESULTS

VHHs specific for carbaryl were generated from an alpaca immunized with the hapten CBR1 coupled to keyhole limpet hemocyanin. An enzyme-linked immunosorbent assay (ELISA) based on the VHH C1 and the coating antigen CBR2-BSA was developed for the detection of carbaryl in cereals. This assay, using an optimized assay buffer (pH 6.5) containing 10% methanol and 0.8% NaCl, has a half-maximum signal inhibition concentration of 5.4 ng mL^-1 and a limit of detection (LOD) of 0.3 ng mL^-1 for carbaryl, and shows low cross reactivity (≤0.8%) with other tested carbamates. The LOD of carbaryl using the VHH-based ELISA was 36 ng g^-1 in rice and maize and 72 ng g^-1 in wheat. Recoveries of carbaryl in spiked rice, maize and wheat samples were in the range of 81-106%, 96-106% and 83-113%, respectively. Relative standard deviations of repeatability and intra-laboratory reproducibility were in the range of 0.8-9.2% and 2.9-9.7%, respectively.

CONCLUSION

The VHH-based ELISA was highly effective in detecting carbaryl in cereal samples after simple sample extraction and dilution. © 2019 Society of Chemical Industry.