Monoclonal antibodies for prophylaxis and therapy of infectious diseases

Mechanistic Insights into the Adsorption of Monoclonal Antibodies at the Water/Vapor Interface

Monoclonal antibodies (mAbs) are active components of therapeutic formulations that interact with the water-vapor interface during manufacturing, storage, and administration. Surface adsorption has been demonstrated to mediate antibody aggregation, which leads to a loss of therapeutic efficacy. Controlling mAb adsorption at interfaces requires a deep understanding of the microscopic processes that lead to adsorption and identification of the protein regions that drive mAb surface activity. Here, we report all-atom molecular dynamics (MD) simulations of the adsorption behavior of a full IgG1-type antibody at the water/vapor interface. We demonstrate that small local changes in the protein structure play a crucial role in promoting adsorption. Also, interfacial adsorption triggers structural changes in the antibody, potentially contributing to the further enhancement of surface activity. Moreover, we identify key amino acid sequences that determine the adsorption of antibodies at the water-air interface and outline strategies to control the surface activity of these important therapeutic proteins.

Resistance-resistant antibacterial treatment strategies

Antibiotic resistance is a major danger to public health that threatens to claim the lives of millions of people per year within the next few decades. Years of necessary administration and excessive application of antibiotics have selected for strains that are resistant to many of our currently available treatments. Due to the high costs and difficulty of developing new antibiotics, the emergence of resistant bacteria is outpacing the introduction of new drugs to fight them. To overcome this problem, many researchers are focusing on developing antibacterial therapeutic strategies that are "resistance-resistant"-regimens that slow or stall resistance development in the targeted pathogens. In this mini review, we outline major examples of novel resistance-resistant therapeutic strategies. We discuss the use of compounds that reduce mutagenesis and thereby decrease the likelihood of resistance emergence. Then, we examine the effectiveness of antibiotic cycling and evolutionary steering, in which a bacterial population is forced by one antibiotic toward susceptibility to another antibiotic. We also consider combination therapies that aim to sabotage defensive mechanisms and eliminate potentially resistant pathogens by combining two antibiotics or combining an antibiotic with other therapeutics, such as antibodies or phages. Finally, we highlight promising future directions in this field, including the potential of applying machine learning and personalized medicine to fight antibiotic resistance emergence and out-maneuver adaptive pathogens.

Miniaturized single-cell technologies for monoclonal antibody discovery

Antibodies (Abs) are among the most important class of biologicals, showcasing a high therapeutic and diagnostic value. In the global therapeutic Ab market, fully-human monoclonal Abs (FH-mAbs) are flourishing thanks to their low immunogenicity and high specificity. The rapidly emerging field of single-cell technologies has paved the way to efficiently discover mAbs by facilitating a fast screening of the antigen (Ag)-specificity and functionality of Abs expressed by B cells. This review summarizes the principles and challenges of the four key concepts to discover mAbs using these technologies, being confinement of single cells using either droplet microfluidics or microstructure arrays, identification of the cells of interest, retrieval of those cells and single-cell sequence determination required for mAb production. This review reveals the enormous potential for mix-and-matching of the above-mentioned strategies, which is illustrated by the plethora of established, highly integrated devices. Lastly, an outlook is given on the many opportunities and challenges that still lie ahead to fully exploit miniaturized single-cell technologies for mAb discovery.

Polyclonal alpaca antibodies protect against hantavirus pulmonary syndrome in a lethal Syrian hamster model

The use of antibody-based therapies for the treatment of high consequence viral pathogens has gained interest over the last fifteen years. Here, we sought to evaluate the use of unique camelid-based IgG antibodies to prevent lethal hantavirus pulmonary syndrome (HPS) in Syrian hamsters. Using purified, polyclonal IgG antibodies generated in DNA-immunized alpacas, we demonstrate that post-exposure treatments reduced viral burdens and organ-specific pathology associated with lethal HPS. Antibody treated animals did not exhibit signs of disease and were completely protected. The unique structures and properties, particularly the reduced size, distinct paratope formation and increased solubility of camelid antibodies, in combination with this study support further pre-clinical evaluation of heavy-chain only antibodies for treatment of severe respiratory diseases, including HPS.

SARS-CoV-2 Neutralizing Antibodies for COVID-19 Prevention and Treatment

Prophylactic and therapeutic drugs are urgently needed to combat coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Over the past year, SARS-CoV-2 neutralizing antibodies have been developed for preventive or therapeutic uses. While neutralizing antibodies target the spike protein, their neutralization potency and breadth vary according to recognition epitopes. Several potent SARS-CoV-2 antibodies have shown degrees of success in preclinical or clinical trials, and the US Food and Drug Administration has issued emergency use authorization for two neutralizing antibody cocktails. Nevertheless, antibody therapy for SARS-CoV-2 still faces potential challenges, including emerging viral variants of concern that have antibody-escape mutations and the potential for antibody-mediated enhancement of infection or inflammation. This review summarizes representative SARS-CoV-2 neutralizing antibodies that have been reported and discusses prospects and challenges for the development of the next generation of COVID-19 preventive or therapeutic antibodies. Expected final online publication date for the Annual Review of Medicine, Volume 73 is January 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Inhibitors of SARS-CoV-2 Entry: Current and Future Opportunities

Recently, a novel coronavirus initially designated 2019-nCoV but now termed SARS-CoV-2 has emerged and raised global concerns due to its virulence. SARS-CoV-2 is the etiological agent of "coronavirus disease 2019", abbreviated to COVID-19, which despite only being identified at the very end of 2019, has now been classified as a pandemic by the World Health Organization (WHO). At this time, no specific prophylactic or postexposure therapy for COVID-19 are currently available. Viral entry is the first step in the SARS-CoV-2 lifecycle and is mediated by the trimeric spike protein. Being the first stage in infection, entry of SARS-CoV-2 into host cells is an extremely attractive therapeutic intervention point. Within this review, we highlight therapeutic intervention strategies for anti-SARS-CoV, MERS-CoV, and other coronaviruses and speculate upon future directions for SARS-CoV-2 entry inhibitor designs.

Generation of Mouse Monoclonal Antibodies Specific to Chikungunya Virus Using ClonaCell-HY Hybridoma Cloning Kit

Monoclonal antibodies offer high specificity and this makes it an important tool for molecular biology, biochemistry and medicine. Typically, monoclonal antibodies are generated by fusing mouse spleen cells that have been immunized with the desired antigen with myeloma cells to create immortalized hybridomas. Here, we describe the generation of monoclonal antibodies that are specific to Chikungunya virus using ClonaCell-HY system.

Immune Human Antibody Libraries for Infectious Diseases

The incident of two children in Europe who died of diphtheria due to a shortage of anti-toxin drugs has highlighted the need for alternative anti-toxins. Historically, antiserum produced from immunised horses have been used to treat diphtheria. Despite the potential of antiserum, the economical and medial concerns associated with the use of animal antiserum has led to its slow market demise. Over the years, new and emerging infectious diseases have grown to be a major global health threat. The emergence of drug-resistant superbugs has also pushed the boundaries of available therapeutics to deal with new infectious diseases. Antibodies have emerged as a possible alternative to combat the continuous onslaught of various infectious agents. The isolation of antibodies against pathogens of infectious diseases isolated from immune libraries utilising phage display has yielded promising results in terms of affinities and neutralizing activities. This chapter focuses on the concept of immune antibody libraries and highlights the application of immune antibody libraries to generate antibodies for various infectious diseases.

A broadly neutralizing human monoclonal antibody is effective against H7N9

Emerging strains of influenza represent a significant public health threat with potential pandemic consequences. Of particular concern are the recently emerged H7N9 strains which cause pneumonia with acute respiratory distress syndrome. Estimates are that nearly 80% of hospitalized patients with H7N9 have received intensive care unit support. VIS410, a human antibody, targets a unique conserved epitope on influenza A. We evaluated the efficacy of VIS410 for neutralization of group 2 influenza strains, including H3N2 and H7N9 strains in vitro and in vivo. VIS410, administered at 50 mg/kg, protected DBA mice infected with A/Anhui/2013 (H7N9), resulting in significant survival benefit upon single-dose (-24 h) or double-dose (-12 h, +48 h) administration (P < 0.001). A single dose of VIS410 at 50 mg/kg (-12 h) combined with oseltamivir at 50 mg/kg (-12 h, twice daily for 7 d) in C57BL/6 mice infected with A/Shanghai 2/2013 (H7N9) resulted in significant decreased lung viral load (P = 0.002) and decreased lung cytokine responses for nine of the 11 cytokines measured. Based on these results, we find that VIS410 may be effective either as monotherapy or combined with antivirals in treating H7N9 disease, as well as disease from other influenza strains.

Isolation of highly active monoclonal antibodies against multiresistant gram-positive bacteria

Multiresistant nosocomial pathogens often cause life-threatening infections that are sometimes untreatable with currently available antibiotics. Staphylococci and enterococci are the predominant Gram-positive species associated with hospital-acquired infections. These infections often lead to extended hospital stay and excess mortality. In this study, a panel of fully human monoclonal antibodies was isolated from a healthy individual by selection of B-cells producing antibodies with high opsonic killing against E. faecalis 12030. Variable domains (VH and VL) of these immunoglobulin genes were amplified by PCR and cloned into an eukaryotic expression vector containing the constant domains of a human IgG1 molecule and the human lambda constant domain. These constructs were transfected into CHO cells and culture supernatants were collected and tested by opsonophagocytic assay against E. faecalis and S. aureus strains (including MRSA). At concentrations of 600 pg/ml, opsonic killing was between 40% and 70% against all strains tested. Monoclonal antibodies were also evaluated in a mouse sepsis model (using S. aureus LAC and E. faecium), a mouse peritonitis model (using S. aureus Newman and LAC) and a rat endocarditis model (using E. faecalis 12030) and were shown to provide protection in all models at a concentration of 4 μg/kg per animal. Here we present a method to produce fully human IgG1 monoclonal antibodies that are opsonic in vitro and protective in vivo against several multiresistant Gram-positive bacteria. The monoclonal antibodies presented in this study are significantly more effective compared to another monoclonal antibody currently in clinical trials.

Functional characterization and evaluation of in vitro protective efficacy of murine monoclonal antibodies BURK24 and BURK37 against Burkholderia pseudomallei

Burkholderia pseudomallei, the causative agent of melioidosis has been recognized by CDC as a category B select agent. Although substantial efforts have been made for development of vaccine molecules against the pathogen, significant hurdles still remain. With no licensed vaccines available and high relapse rate of the disease, there is a pressing need for development of alternate protection strategies. Antibody-mediated passive protection is promising in this regard and our primary interest was to unravel this frontier of specific mAbs against Burkholderia pseudomallei infections, as functional characterization of antibodies is a pre-requisite to demonstrate them as protective molecules. To achieve this, we designed our study on in vitro-based approach and assessed two mAbs, namely BURK24 and BURK37, reactive with outer membrane proteins and lipopolysaccharide of the pathogen respectively, for their ability to manifest inhibitory effects on the pathogenesis mechanisms of B. pseudomallei including biofilm formation, invasion and induction of apoptosis. The experiments were performed using B. pseudomallei standard strain NCTC 10274 and a clinical isolate, B. pseudomallei 621 recovered from a septicemia patient with diabetic ailment. The growth kinetic studies of the pathogen in presence of various concentrations of each individual mAb revealed their anti-bacterial properties. Minimal inhibitory concentration and minimal bactericidal concentration of both the mAbs were determined by using standards of Clinical and Laboratory Standards Institute (CLSI) and experiments were performed using individual mAbs at their respective bacteriostatic concentration. As an outcome, both mAbs exhibited significant anti-Burkholderia pseudomallei properties. They limited the formation of biofilm by the bacterium and completely crippled its invasion into human alveolar adenocarcinoma epithelial cells. Also, the mAbs were appreciably successful in preventing the bacterium to induce apoptosis in A549 cells. The present study design revealed the protection attributes possessed by BURK24 and BURK37 that has to be further substantiated by additional in vivo studies.

A simple methodology for conversion of mouse monoclonal antibody to human-mouse chimeric form

Passive immunotherapy has mainly been used as a therapy against cancer and inflammatory conditions. Recent studies have shown that monoclonal antibody-(mAb-) based passive immunotherapy is a promising approach to combat virus infection. Specific mouse mAbs can be routinely generated in large amounts with the use of hybridoma technology but these cannot be used for therapy in human beings due to their immunogenicity. Therefore, the development of chimeric and humanized mAbs is important for therapeutic purpose. This is facilitated by a variety of molecular techniques like recombinant DNA technology and the better understanding of the structure and function of antibody. The human-mouse chimeric forms allow detailed analysis of the mechanism of inhibition and the potential for therapeutic applications. Here, a step-by-step description of the conversion process will be described. The commercial availability of the reagents required in each step means that this experimentation can be easily set up in research laboratories.

Antibody-recruiting molecules: an emerging paradigm for engaging immune function in treating human disease

Synthetic immunology, the development of synthetic systems capable of modulating and/or manipulating immunological functions, represents an emerging field of research with manifold possibilities. One focus of this area has been to create low molecular weight synthetic species, called antibody-recruiting molecules (ARMs), which are capable of enhancing antibody binding to disease-relevant cells or viruses, thus leading to their immune-mediated clearance. This article provides a thorough discussion of contributions in this area, beginning with the history of small-molecule-based technologies for modulating antibody recognition, followed by a systematic review of the various applications of ARM-based strategies. Thus, we describe ARMs capable of targeting cancer, bacteria, and viral pathogens, along with some of the scientific discoveries that have resulted from their development. Research in this area underscores the many exciting possibilities at the interface of organic chemistry and immunobiology and is positioned to advance both basic and clinical science in the years to come.

Monoclonal antibodies in infectious diseases: clinical pipeline in 2011

Of the more than 20 monoclonal antibodies (mAbs) generated to combat infectious diseases (ID) that are in clinical development in 2011, most are in phase 1 or 2 and are directed against either viruses or bacterial toxins. Several high-profile anti-ID mAbs have recently failed in clinical trials. Despite the advancement in recombinant engineering technologies, anti-ID mAbs have yet to deliver on their promise as "magic bullets," especially against nosocomial infections. A paradigm shift in favor of developing mAb combinations, which act synergistically with each other or with small molecule drugs, may be required to move the field forward.

Antibodies in infectious diseases: polyclonals, monoclonals and niche biotechnology

Antibody preparations have a long history of providing protection from infectious diseases. Although antibodies remain the only natural host-derived defense mechanism capable of completely preventing infection, as products, they compete against inexpensive therapeutics such as antibiotics, small molecule inhibitors and active vaccines. The continued discovery in the monoclonal antibody (mAb) field of leads with broadened cross neutralization of viruses and demonstrable synergy of antibody with antibiotics for bacterial diseases, clearly show that innovation remains. The commercial success of mAbs in chronic disease has not been paralleled in infectious diseases for several reasons. Infectious disease immunotherapeutics are limited in scope as endemic diseases necessitate active vaccine development. Also, the complexity of these small markets draws the interest of niche companies rather than big pharmaceutical corporations. Lastly, the cost of goods for mAb therapeutics is inherently high for infectious agents due to the need for antibody cocktails, which better mimic polyclonal immunoglobulin preparations and prevent antigenic escape. In cases where vaccine or convalescent populations are available, current polyclonal hyperimmune immunoglobulin preparations (pIgG), with modern and highly efficient purification technology and standardized assays for potency, can make economic sense. Recent innovations to broaden the potency of mAb therapies, while reducing cost of production, are discussed herein. On the basis of centuries of effective use of Ab treatments, and with growing immunocompromised populations, the question is not whether antibodies have a bright future for infectious agents, but rather what formats are cost effective and generate safe and efficacious treatments to satisfy regulatory approval.

The state of antibody therapy

Therapeutic antibodies are widely used in the treatment of various diseases and disease conditions, including cardiovascular diseases, autoimmune disorders, malignancies, and infections. With at least 23 therapeutic agents currently in clinical use and a successful business generating large revenues, major technological advances are now in place to improve the specificity and efficacy of those antibodies already in the market and also generate new, safe and effective macromolecules for the treatment of other ailments. This review provides a summary of the current state of antibody therapy, highlights and discusses recent developments in the field of antibody-based therapeutics production, combination therapy and shows the status of some of the agents that are in clinical trial.

Preclinical in vitro and in vivo characterization of the fully human monoclonal IgM antibody KBPA101 specific for Pseudomonas aeruginosa serotype IATS-O11

Pseudomonas aeruginosa infection in ventilator-associated pneumonia is a serious and often life-threatening complication in intensive care unit patients, and new treatment options are needed. We used B-cell-enriched peripheral blood lymphocytes from a volunteer immunized with a P. aeruginosa O-polysaccharide-toxin A conjugate vaccine to generate human hybridoma cell lines producing monoclonal antibodies specific for individual P. aeruginosa lipopolysaccharide serotypes. The fully human monoclonal antibody secreted by one of these lines, KBPA101, is an IgM/kappa antibody that binds P. aeruginosa of International Antigenic Typing System (IATS) serotype O11 with high avidity (5.81 x 10(7) M(-1) +/- 2.8 x 10(7) M(-1)) without cross-reacting with other serotypes. KBPA101 specifically opsonized the P. aeruginosa of IATS O11 serotype and mediated complement-dependent phagocytosis in vitro by the human monocyte-like cell line HL-60 at a very low concentration (half-maximal phagocytosis at 0.16 ng/ml). In vivo evaluation of KBPA101 demonstrated a dose-response relationship for protection against systemic infections in a murine burn wound sepsis model, where 70 to 100% of animals were protected against lethal challenges with P. aeruginosa at doses as low as 5 microg/animal. Furthermore, a high efficacy of KBPA101 in protection from local respiratory infections in an acute lung infection model in mice was demonstrated. Preclinical toxicology evaluation on human tissue, in rabbits, and in mice did not indicate any toxicity of KBPA101. Based on these preclinical findings, the first human clinical trials have been initiated.

Monoclonal antibody-based therapies for microbial diseases

The monoclonal antibody (mAb) revolution that currently provides many new options for the treatment of neoplastic and inflammatory diseases has largely bypassed the field of infectious diseases. Only one mAb is licensed for use against an infectious disease, although there are many in various stages of development. This situation is peculiar given that serum therapy was one of the first effective treatments for microbial diseases and that specific antibodies have numerous antimicrobial properties. The underdevelopment and underutilization of mAb therapies for microbial diseases has various complex explanations that include the current availability of antimicrobial drugs, small markets, high costs and microbial antigenic variation. However, there are signs that the climate for mAb therapeutics in infectious diseases is changing given increasing antibiotic drug resistance, the emergence of new pathogenic microbes for which no therapy is available, and development of mAb cocktail formulations. Currently, the major hurdle for the widespread introduction of mAb therapies for microbial diseases is economic, given the high costs of immunoglobulin preparations and relatively small markets. Despite these obstacles there are numerous opportunities for mAb development against microbial diseases and the development of radioimmunotherapy provides new options for enhancing the magic bullet. Hence, there is cautious optimism that the years ahead will see more mAbs in clinical use against microbial diseases.

Murine IgG1 and IgG3 isotype switch variants promote phagocytosis of Cryptococcus neoformans through different receptors

Almost 3 decades ago, murine IgG3 was proposed to interact with a different receptor than the other IgG subclasses, but the issue remains unresolved. The question of whether a specific receptor exists for IgG3 is critically important for understanding Ab-mediated immunity against Cryptococcus neoformans, where the different isotypes manifest profound differences in protective efficacy. In this study, we revisited this question by analyzing IgG1- and IgG3-mediated phagocytosis with variable region-identical mAbs using mouse macrophages deficient in various receptors and in conditions of FcgammaR and complement receptor blockage with specific Abs. IgG3 was an efficient opsonin for C. neoformans in FcgammaR- and CD18-deficient cells and in the presence of blocking Abs to FcgammaR and complement receptor. Like IgG1, IgG3-mediated phagocytosis was associated with fungal residence in a mature phagosome that was followed by intracellular replication and exocytosis events. We conclude that a specific receptor for IgG3 exists in mice that is structurally different from the known FcgammaRs.

[Novel vaccination concepts on the basis of modern insights into immunology]

Since their introduction more than 200 years ago, vaccines have prevented millions of deaths caused by infectious diseases. This progress was possible because these vaccines protect through antibodies, which are relatively easily stimulated. In the meantime, we understand that diseases such as AIDS, tuberculosis, malaria and hepatitis C cannot be tackled by these conventional approaches. Recent insights into immunology provide the basis for the development of custom-tailored vaccines to successfully combat these threatening infections. These new generation vaccines comprise components that modulate the mediators of immunity (B cells, T cells, antigen-presenting cells and cytokines) in such a way that the best possible immune response develops. Alternative application methods offer the possibility to further improve the immune response. Thus, hope remains that the remarkable increase in knowledge in the areas of immunology and infectious disease research will help to successfully control infectious diseases.