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Khalil I, Anderson JD, Bagamian KH, Baqar S, Giersing B, Hausdorff WP, Marshall C, Porter CK, Walker RI, Bourgeois AL. Vaccine value profile for enterotoxigenic Escherichia coli (ETEC). Vaccine 2023; 41 Suppl 2:S95-S113. [PMID: 37951695 DOI: 10.1016/j.vaccine.2023.02.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 11/28/2022] [Accepted: 02/05/2023] [Indexed: 11/14/2023]
Abstract
Enterotoxigenic Escherichia coli (ETEC) is one of the leading bacterial causes of diarrhoea, especially among children in low-resource settings, and travellers and military personnel from high-income countries. WHO's primary strategic goal for ETEC vaccine development is to develop a safe, effective, and affordable ETEC vaccine that reduces mortality and morbidity due to moderate-to-severe diarrhoeal disease in infants and children under 5 years of age in LMICs, as well as the long-term negative health impact on infant physical and cognitive development resulting from infection with this enteric pathogen. An effective ETEC vaccine will also likely reduce the need for antibiotic treatment and help limit the further emergence of antimicrobial resistance bacterial pathogens. The lead ETEC vaccine candidate, ETVAX, has shown field efficacy in travellers and has moved into field efficacy testing in LMIC infants and children. A Phase 3 efficacy study in LMIC infants is projected to start in 2024 and plans for a Phase 3 trial in travellers are under discussion with the U.S. FDA. Licensing for both travel and LMIC indications is projected to be feasible in the next 5-8 years. Given increasing recognition of its negative impact on child health and development in LMICs and predominance as the leading etiology of travellers' diarrhoea (TD), a standalone vaccine for ETEC is more cost-effective than vaccines targeting other TD pathogens, and a viable commercial market also exists. In contrast, combination of an ETEC vaccine with other vaccines for childhood pathogens in LMICs would maximize protection in a more cost-effective manner than a series of stand-alone vaccines. This 'Vaccine Value Profile' (VVP) for ETEC is intended to provide a high-level, holistic assessment of available data to inform the potential public health, economic and societal value of pipeline vaccines and vaccine-like products. This VVP was developed by a working group of subject matter experts from academia, non-profit organizations, public private partnerships, and multi-lateral organizations. All contributors have extensive expertise on various elements of the ETEC VVP and collectively aimed to identify current research and knowledge gaps. The VVP was developed using only existing and publicly available information.
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Affiliation(s)
- Ibrahim Khalil
- Department of Global Health, University of Washington, Seattle, WA 98195, USA.
| | - John D Anderson
- Bagamian Scientific Consulting, LLC, Gainesville, FL 32601, USA; Office of Health Affairs, West Virginia University, Morgantown, WV 26505, USA
| | - Karoun H Bagamian
- Bagamian Scientific Consulting, LLC, Gainesville, FL 32601, USA; Department of Environmental and Global Health, University of Florida, Gainesville, FL 32603, USA
| | - Shahida Baqar
- National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Birgitte Giersing
- Department of Immunization, Vaccines and Biologicals (IVB), World Health Organization (WHO), Geneva, Switzerland
| | - William P Hausdorff
- PATH, Center for Vaccine Innovation and Access, 455 Massachusetts Ave NW, Washington, DC 20001 USA; Faculty of Medicine, Université Libre de Bruxelles, Brussels 1070, Belgium
| | - Caroline Marshall
- Department of Immunization, Vaccines and Biologicals (IVB), World Health Organization (WHO), Geneva, Switzerland
| | - Chad K Porter
- Directorate for DoD Infectious Diseases Research, Naval Medical Research Command, Silver Spring, MD 20190, USA
| | - Richard I Walker
- PATH, Center for Vaccine Innovation and Access, 455 Massachusetts Ave NW, Washington, DC 20001 USA
| | - A Louis Bourgeois
- PATH, Center for Vaccine Innovation and Access, 455 Massachusetts Ave NW, Washington, DC 20001 USA
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Gutiérrez RL, Riddle MS, Porter CK, Maciel M, Poole ST, Laird RM, Lane M, Turiansky GW, Jarell A, Savarino SJ. A First in Human Clinical Trial Assessing the Safety and Immunogenicity of Two Intradermally Delivered Enterotoxigenic Escherichia coli CFA/I Fimbrial Tip Adhesin Antigens with and without Heat-Labile Enterotoxin with Mutation LT(R192G). Microorganisms 2023; 11:2689. [PMID: 38004700 PMCID: PMC10672875 DOI: 10.3390/microorganisms11112689] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2023] [Revised: 10/25/2023] [Accepted: 10/31/2023] [Indexed: 11/26/2023] Open
Abstract
INTRODUCTION Enterotoxigenic E. coli (ETEC) is a leading cause of diarrhea in travelers as well as for children living in low- to middle-income countries. ETEC adhere to intestinal epithelium via colonization factors (CFs). CFA/I, a common CF, is composed of a polymeric stalk and a tip-localized minor adhesive subunit, CfaE. Vaccine delivery by the transcutaneous immunization of dscCfaE was safe but was poorly immunogenic in a phase 1 trial when administered to volunteers with LTR(192G) and mLT. To potentially enhance the immunogenicity of CfaE while still delivering via a cutaneous route, we evaluated the safety and immunogenicity of two CfaE constructs administered intradermally (ID) with or without mLT. METHODS CfaE was evaluated as a donor strand-complemented construct (dscCfaE) and as a chimeric construct (Chimera) in which dscCfaE replaces the A1 domain of the cholera toxin A subunit and assembles non-covalently with the pentamer of heat-labile toxin B (LTB). Subjects received three ID vaccinations three weeks apart with either dscCfaE (1, 5, and 25 µg) or Chimera (2.6 and 12.9 µg) with and without 0.1 µg of mLT. Subjects were monitored for local and systemic adverse events. Immunogenicity was evaluated by serum and antibody-secreting cell (ASC) responses. RESULTS The vaccine was well-tolerated with predominantly mild and moderate local vaccine site reactions characterized by erythema, induration and post-inflammatory hyperpigmentation. High rates of serologic and ASC responses were seen across study groups with the most robust responses observed in subjects receiving 25 µg of dscCfaE with 0.1 mcg of LT(R192G). CONCLUSION Both ETEC adhesin vaccine prototypes were safe and immunogenic when co-administered with mLT by the ID route. The observed immune responses induced with the high dose of dscCfaE and mLT warrant further assessment in a controlled human infection model.
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Affiliation(s)
- Ramiro L. Gutiérrez
- Naval Medical Research Command, Silver Spring, MD 20910, USA; (R.L.G.); (S.T.P.)
| | - Mark S. Riddle
- Naval Medical Research Command, Silver Spring, MD 20910, USA; (R.L.G.); (S.T.P.)
| | - Chad K. Porter
- Naval Medical Research Command, Silver Spring, MD 20910, USA; (R.L.G.); (S.T.P.)
- Uniformed Services University of the Health Sciences, Bethesda, MD 20814, USA
| | - Milton Maciel
- Naval Medical Research Command, Silver Spring, MD 20910, USA; (R.L.G.); (S.T.P.)
- Uniformed Services University of the Health Sciences, Bethesda, MD 20814, USA
- Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc., Bethesda, MD 20817, USA
| | - Steven T. Poole
- Naval Medical Research Command, Silver Spring, MD 20910, USA; (R.L.G.); (S.T.P.)
- Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc., Bethesda, MD 20817, USA
| | - Renee M. Laird
- Naval Medical Research Command, Silver Spring, MD 20910, USA; (R.L.G.); (S.T.P.)
- Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc., Bethesda, MD 20817, USA
| | - Michelle Lane
- Naval Medical Research Command, Silver Spring, MD 20910, USA; (R.L.G.); (S.T.P.)
| | - George W. Turiansky
- Uniformed Services University of the Health Sciences, Bethesda, MD 20814, USA
| | - Abel Jarell
- Walter Reed National Military Medical Center, Bethesda, MD 20814, USA
| | - Stephen J. Savarino
- Naval Medical Research Command, Silver Spring, MD 20910, USA; (R.L.G.); (S.T.P.)
- Uniformed Services University of the Health Sciences, Bethesda, MD 20814, USA
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Bajoria S, Antunez LR, Kumru OS, Klempner M, Wang Y, Cavacini LA, Joshi SB, Volkin DB. Formulation Studies to Develop Low-Cost, Orally-Delivered Secretory IgA Monoclonal Antibodies for Passive Immunization Against Enterotoxigenic Escherichia coli. J Pharm Sci 2023; 112:1832-1844. [PMID: 37040833 DOI: 10.1016/j.xphs.2023.04.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Revised: 04/06/2023] [Accepted: 04/06/2023] [Indexed: 04/13/2023]
Abstract
Enterotoxigenic Escherichia coli (ETEC) is a common cause for diarrheal infections in children in low- and middle-income countries (LMICs). To date, no ETEC vaccine candidates have been approved. Passive immunization with low-cost, oral formulations of secretory IgA (sIgA) against ETEC is an alternative approach to protect high-risk populations in LMICs. Using a model sIgA monoclonal antibody (anti-LT sIgA2-mAb), the stability profiles of different formulations were assessed during storage and in in vitro digestion models (mimicking in vivo oral delivery). First, by employing various physicochemical techniques and a LT-antigen binding assay, three formulations with varying acid-neutralizing capacity (ANC) were evaluated to stabilize sIgA2-mAb during stress studies (freeze-thaw, agitation, elevated temperature) and during exposure to gastric phase digestion. Next, a low-volume, in vitro intestinal digestion model was developed to screen various additives to stabilize sIgA2-mAb in the intestinal phase. Finally, combinations of high ANC buffers and decoy proteins were assessed to collectively protect sIgA2-mAb during in vitro sequential (stomach to intestine) digestion. Based on the results, we demonstrate the feasibility of low-cost, 'single-vial', liquid formulations of sIgA-mAbs delivered orally after infant feeding for passive immunization, and we suggest future work based on a combination of in vitro and in vivo stability considerations.
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Affiliation(s)
- Sakshi Bajoria
- Department of Pharmaceutical Chemistry, Vaccine Analytics and Formulation Center (VAFC), University of Kansas, Lawrence, KS 66047, USA
| | - Lorena R Antunez
- Department of Pharmaceutical Chemistry, Vaccine Analytics and Formulation Center (VAFC), University of Kansas, Lawrence, KS 66047, USA
| | - Ozan S Kumru
- Department of Pharmaceutical Chemistry, Vaccine Analytics and Formulation Center (VAFC), University of Kansas, Lawrence, KS 66047, USA
| | - Mark Klempner
- MassBiologics of the University of Massachusetts Chan Medical School, Boston, MA 02126, USA
| | - Yang Wang
- MassBiologics of the University of Massachusetts Chan Medical School, Boston, MA 02126, USA
| | - Lisa A Cavacini
- MassBiologics of the University of Massachusetts Chan Medical School, Boston, MA 02126, USA
| | - Sangeeta B Joshi
- Department of Pharmaceutical Chemistry, Vaccine Analytics and Formulation Center (VAFC), University of Kansas, Lawrence, KS 66047, USA
| | - David B Volkin
- Department of Pharmaceutical Chemistry, Vaccine Analytics and Formulation Center (VAFC), University of Kansas, Lawrence, KS 66047, USA.
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Geurtsen J, de Been M, Weerdenburg E, Zomer A, McNally A, Poolman J. Genomics and pathotypes of the many faces of Escherichia coli. FEMS Microbiol Rev 2022; 46:fuac031. [PMID: 35749579 PMCID: PMC9629502 DOI: 10.1093/femsre/fuac031] [Citation(s) in RCA: 43] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2021] [Accepted: 06/22/2022] [Indexed: 01/09/2023] Open
Abstract
Escherichia coli is the most researched microbial organism in the world. Its varied impact on human health, consisting of commensalism, gastrointestinal disease, or extraintestinal pathologies, has generated a separation of the species into at least eleven pathotypes (also known as pathovars). These are broadly split into two groups, intestinal pathogenic E. coli (InPEC) and extraintestinal pathogenic E. coli (ExPEC). However, components of E. coli's infinite open accessory genome are horizontally transferred with substantial frequency, creating pathogenic hybrid strains that defy a clear pathotype designation. Here, we take a birds-eye view of the E. coli species, characterizing it from historical, clinical, and genetic perspectives. We examine the wide spectrum of human disease caused by E. coli, the genome content of the bacterium, and its propensity to acquire, exchange, and maintain antibiotic resistance genes and virulence traits. Our portrayal of the species also discusses elements that have shaped its overall population structure and summarizes the current state of vaccine development targeted at the most frequent E. coli pathovars. In our conclusions, we advocate streamlining efforts for clinical reporting of ExPEC, and emphasize the pathogenic potential that exists throughout the entire species.
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Affiliation(s)
- Jeroen Geurtsen
- Janssen Vaccines and Prevention B.V., 2333 Leiden, the Netherlands
| | - Mark de Been
- Janssen Vaccines and Prevention B.V., 2333 Leiden, the Netherlands
| | | | - Aldert Zomer
- Department of Infectious Diseases and Immunology, Faculty of Veterinary Medicine, Utrecht University, 3584 Utrecht, the Netherlands
| | - Alan McNally
- Institute of Microbiology and Infection, College of Medical and Dental Sciences, University of Birmingham, B15 2TT Birmingham, United Kingdom
| | - Jan Poolman
- Janssen Vaccines and Prevention B.V., 2333 Leiden, the Netherlands
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5
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Langel SN, Blasi M, Permar SR. Maternal immune protection against infectious diseases. Cell Host Microbe 2022; 30:660-674. [PMID: 35550669 DOI: 10.1016/j.chom.2022.04.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The maternal immune system protects developing offspring against pathogens before birth via transplacental transfer and after birth through secreted milk. This transferred maternal immunity influences each generation's susceptibility to infections and responsiveness to immunization. Thus, boosting immunity in the maternal-neonatal dyad is a potentially valuable public health strategy. Additionally, at critical times during fetal and postnatal development, environmental factors and immune stimuli influence immune development. These "windows of opportunity" offer a chance to identify both risk and protective factors that promote long-term health and limit disease. Here, we review pre- and postpartum maternal immune factors that protect against infectious agents in offspring and how they may shape the infant's immune landscape over time. Additionally, we discuss the influence of maternal immunity on the responsiveness to immunization in early life. Lastly, when maternal factors are insufficient to prevent neonatal infectious diseases, we discuss pre- and postnatal therapeutic strategies for the maternal-neonatal dyad.
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Affiliation(s)
- Stephanie N Langel
- Department of Surgery, Duke Center for Human Systems Immunology, Durham, NC, USA
| | - Maria Blasi
- Duke Human Vaccine Institute, Duke University Medical Center, Durham, NC, USA; Department of Medicine, Division of Infectious Diseases, Duke University Medical Center, Durham, NC, USA
| | - Sallie R Permar
- Department of Pediatrics, Weill Cornell Medicine, New York, NY, USA.
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Richards A, Baranova D, Mantis NJ. The prospect of orally administered monoclonal secretory IgA (SIgA) antibodies to prevent enteric bacterial infections. Hum Vaccin Immunother 2022; 18:1964317. [PMID: 34491878 PMCID: PMC9103515 DOI: 10.1080/21645515.2021.1964317] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Revised: 07/08/2021] [Accepted: 07/30/2021] [Indexed: 12/20/2022] Open
Abstract
Eliminating diarrheal diseases as a leading cause of childhood morbidity and mortality in low- and middle-income countries (LMICs) will require multiple intervention strategies. In this review, we spotlight a series of preclinical studies investigating the potential of orally administered monoclonal secretory IgA (SIgA) antibodies (MAbs) to reduce disease associated with three enteric bacterial pathogens: Campylobacter jejuni, enterotoxigenic Escherichia coli (ETEC), and invasive Salmonella enterica serovar Typhimurium. IgA MAbs targeting bacterial surface antigens (flagella, adhesins, and lipopolysaccharide) were generated from mice, humanized mice, and human tonsillar B cells. Recombinant SIgA1 and/or SIgA2 derivates of those MAbs were purified from supernatants following transient transfection of 293 cells with plasmids encoding antibody heavy and light chains, J-chain, and secretory component (SC). When administered to mice by gavage immediately prior to (or admixed with) the bacterial challenge, SIgA MAbs reduced infection C. jejuni, ETEC, and S. Typhimurium infections. Fv-matched IgG1 MAbs by comparison were largely ineffective against C. jejuni and S. Typhimurium under the same conditions, although they were partially effective against ETEC. While these findings highlight future applications of orally administered SIgA, the studies also underscored the fundamental challenges associated with using MAbs as prophylactic tools against enteric bacterial diseases.
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Affiliation(s)
- Angelene Richards
- Department of Biomedical Sciences, University at Albany School, Albany, NY, USA
| | - Danielle Baranova
- Department of Biomedical Sciences, University at Albany School, Albany, NY, USA
| | - Nicholas J. Mantis
- Department of Biomedical Sciences, University at Albany School, Albany, NY, USA
- Division of Infectious Diseases, Wadsworth Center, New York State Department of Health, Albany, NY, USA
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7
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Zhang Y, Tan P, Zhao Y, Ma X. Enterotoxigenic Escherichia coli: intestinal pathogenesis mechanisms and colonization resistance by gut microbiota. Gut Microbes 2022; 14:2055943. [PMID: 35358002 PMCID: PMC8973357 DOI: 10.1080/19490976.2022.2055943] [Citation(s) in RCA: 42] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Enterotoxigenic Escherichia coli (ETEC) is a major cause of diarrhea in children and travelers in developing countries. ETEC is characterized by the ability to produce major virulence factors including colonization factors (CFs) and enterotoxins, that bind to specific receptors on epithelial cells and induce diarrhea. The gut microbiota is a stable and sophisticated ecosystem that performs a range of beneficial functions for the host, including protection against pathogen colonization. Understanding the pathogenic mechanisms of ETEC and the interaction between the gut microbiota and ETEC represents not only a research need but also an opportunity and challenge to develop precautions for ETEC infection. Herein, this review focuses on recent discoveries about ETEC etiology, pathogenesis and clinical manifestation, and discusses the colonization resistances mediated by gut microbiota, as well as preventative strategies against ETEC with an aim to provide novel insights that can reduce the adverse effect on human health.
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Affiliation(s)
- Yucheng Zhang
- State Key Laboratory of Animal Nutrition, Department of Animal Nutrition and Feed Science, China Agricultural University, Beijing, China
| | - Peng Tan
- State Key Laboratory of Animal Nutrition, Department of Animal Nutrition and Feed Science, China Agricultural University, Beijing, China
| | - Ying Zhao
- State Key Laboratory of Animal Nutrition, Department of Animal Nutrition and Feed Science, China Agricultural University, Beijing, China
| | - Xi Ma
- State Key Laboratory of Animal Nutrition, Department of Animal Nutrition and Feed Science, China Agricultural University, Beijing, China,CONTACT Xi Ma State Key Laboratory of Animal Nutrition, Department of Animal Nutrition and Feed Science, China Agricultural University, Beijing, China
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Richards AF, Torres-Velez FJ, Mantis NJ. Salmonella Uptake into Gut-Associated Lymphoid Tissues: Implications for Targeted Mucosal Vaccine Design and Delivery. METHODS IN MOLECULAR BIOLOGY (CLIFTON, N.J.) 2022; 2410:305-324. [PMID: 34914054 DOI: 10.1007/978-1-0716-1884-4_15] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Peyer's patches are organized gut-associated lymphoid tissues (GALT) in the small intestine and the primary route by which particulate antigens, including viruses and bacteria, are sampled by the mucosal immune system. Antigen sampling occurs through M cells, a specialized epithelial cell type located in the follicle-associated epithelium (FAE) that overlie Peyer's patch lymphoid follicles. While Peyer's patches play an integral role in intestinal homeostasis, they are also a gateway by which enteric pathogens, like Salmonella enterica serovar Typhimurium (STm), cross the intestinal barrier. Once pathogens like STm gain access to the underlying network of mucosal dendritic cells and macrophages they can spread systemically. Thus, Peyer's patches are at the crossroads of mucosal immunity and intestinal pathogenesis. In this chapter, we provide detailed methods to assess STm entry into mouse Peyer's patch tissues. We describe Peyer's patch collection methods and provide strategies to enumerate bacterial uptake. We also detail a method for quantifying bacterial shedding from infected animals and provide an immunohistochemistry protocol for the localization of STm along the gastrointestinal tract and insight into pathogen transit in the presence of protective antibodies. While the protocols are written for STm, they are easily tailored to other enteric pathogens.
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Affiliation(s)
- Angelene F Richards
- Department of Biomedical Sciences, University at Albany School of Public Health, Albany, NY, USA.,Division of Infectious Diseases, Wadsworth Center, New York State Department of Health, Albany, NY, USA
| | - Fernando J Torres-Velez
- Division of Infectious Diseases, Wadsworth Center, New York State Department of Health, Albany, NY, USA
| | - Nicholas J Mantis
- Department of Biomedical Sciences, University at Albany School of Public Health, Albany, NY, USA. .,Division of Infectious Diseases, Wadsworth Center, New York State Department of Health, Albany, NY, USA.
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Shinkura R. Therapeutic immunoglobulin A antibody for dysbiosis-related diseases. Int Immunol 2021; 33:787-790. [PMID: 34492105 PMCID: PMC8499904 DOI: 10.1093/intimm/dxab066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Accepted: 09/07/2021] [Indexed: 11/12/2022] Open
Abstract
Dysbiosis is alterations in the microbial composition compared with a healthy microbiota and often features a reduction in gut microbial diversity and a change in microbial taxa. Dysbiosis, especially in the gut, has also been proposed to play a crucial role in the pathogenesis of a wide variety of diseases, including inflammatory bowel disease, colorectal cancer, cardiovascular disease, obesity, diabetes and multiple sclerosis. A body of evidence has shown that intestinal polymeric immunoglobulin A (IgA) antibodies are important to regulate the gut microbiota as well as to exclude pathogenic bacteria or viral infection such as influenza and SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) at mucosal sites. Since the 1970s, trials for oral administration of therapeutic IgA or IgG have been performed mainly to treat infectious enteritis caused by pathogenic Escherichia coli or Clostridium difficile. However, few of them have been successfully developed for clinical application up to now. In addition to the protective function against intestinal pathogens, IgA is well known to modulate the gut commensal microbiota leading to symbiosis. Nevertheless, the development of therapeutic IgA drugs to treat dysbiosis is not progressing. In this review, the advantages of therapeutic IgA antibodies and the problems for their development will be discussed.
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Affiliation(s)
- Reiko Shinkura
- Laboratory of Immunology and Infection Control, Institute for Quantitative Biosciences, University of Tokyo, Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan
- Collaborative Research Institute for Innovative Microbiology, University of Tokyo, 1‑1‑1 Yayoi, Bunkyo‑ku, Tokyo 113‑0032, Japan
- Core Research for Evolutional Science and Technology, Japan Agency for Medical Research and Development, Tokyo 100-0004, Japan
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10
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Liu Y, Maciel M, O’Dowd A, Poole ST, Rollenhagen JE, Etobayeva IV, Savarino SJ. Development and Comparison of a Panel of Modified CS17 Fimbrial Tip Adhesin Proteins as Components for an Adhesin-Based Vaccine against Enterotoxigenic Escherichia coli. Microorganisms 2021; 9:microorganisms9081646. [PMID: 34442726 PMCID: PMC8401227 DOI: 10.3390/microorganisms9081646] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2021] [Revised: 07/25/2021] [Accepted: 07/27/2021] [Indexed: 11/23/2022] Open
Abstract
Enterotoxigenic Escherichia coli (ETEC) is a leading cause of diarrhea in travelers and children in resource-limited countries. ETEC colonization factors, fimbrial tip adhesins and enterotoxins are key virulence factors, and thus have been studied as vaccine candidates. Some prevalent colonization factors, including CFA/I and CS17, belong to the class 5 family. We previously found that passive oral administration of hyperimmune bovine colostral IgG (bIgG) raised against dscCfaE (donor strand complemented CFA/I tip adhesin) protected volunteers against CFA/I+ ETEC challenge, while anti-dscCsbD bIgG (CS17 tip adhesin) did not confer protection. These findings led us to develop and optimize a panel of alternative CsbD-based vaccine candidates based on allele matching and in silico protein engineering. Physicochemical characterizations revealed that an optimized vaccine candidate dscCsbDLSN139(P218A/G3) had the greatest thermal stability among the six tested dscCsbD adhesins, whereas the overall secondary structures and solubility of these adhesins had no obvious differences. Importantly, dscCsbDLSN139(P218A/G3) elicited significantly higher CS17+ ETEC hemagglutination inhibition titers in sera from mice intranasally immunized with the panel of dscCsbD adhesins, while no significant difference was observed among heterologous neutralizing titers. Our results strongly advocate for the incorporation of these modifications into a new generation of CsbD-based ETEC vaccine candidates.
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Affiliation(s)
- Yang Liu
- Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, MD 20817, USA; (M.M.J.); (A.O.); (S.T.P.); (J.E.R.)
- Correspondence:
| | - Milton Maciel
- Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, MD 20817, USA; (M.M.J.); (A.O.); (S.T.P.); (J.E.R.)
| | - Aisling O’Dowd
- Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, MD 20817, USA; (M.M.J.); (A.O.); (S.T.P.); (J.E.R.)
| | - Steven T. Poole
- Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, MD 20817, USA; (M.M.J.); (A.O.); (S.T.P.); (J.E.R.)
| | - Julianne E. Rollenhagen
- Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, MD 20817, USA; (M.M.J.); (A.O.); (S.T.P.); (J.E.R.)
| | - Irina V. Etobayeva
- Enteric Diseases Department, Naval Medical Research Center, Silver Spring, MD 20910, USA; (I.V.E.); (S.J.S.)
| | - Stephen J. Savarino
- Enteric Diseases Department, Naval Medical Research Center, Silver Spring, MD 20910, USA; (I.V.E.); (S.J.S.)
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11
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Walker R, Kaminski RW, Porter C, Choy RKM, White JA, Fleckenstein JM, Cassels F, Bourgeois L. Vaccines for Protecting Infants from Bacterial Causes of Diarrheal Disease. Microorganisms 2021; 9:1382. [PMID: 34202102 PMCID: PMC8303436 DOI: 10.3390/microorganisms9071382] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Revised: 06/16/2021] [Accepted: 06/21/2021] [Indexed: 12/22/2022] Open
Abstract
The global diarrheal disease burden for Shigella, enterotoxigenic Escherichia coli (ETEC), and Campylobacter is estimated to be 88M, 75M, and 75M cases annually, respectively. A vaccine against this target trio of enteric pathogens could address about one-third of diarrhea cases in children. All three of these pathogens contribute to growth stunting and have demonstrated increasing resistance to antimicrobial agents. Several combinations of antigens are now recognized that could be effective for inducing protective immunity against each of the three target pathogens in a single vaccine for oral administration or parenteral injection. The vaccine combinations proposed here would result in a final product consistent with the World Health Organization's (WHO) preferred product characteristics for ETEC and Shigella vaccines, and improve the vaccine prospects for support from Gavi, the Vaccine Alliance, and widespread uptake by low- and middle-income countries' (LMIC) public health stakeholders. Broadly protective antigens will enable multi-pathogen vaccines to be efficiently developed and cost-effective. This review describes how emerging discoveries for each pathogen component of the target trio could be used to make vaccines, which could help reduce a major cause of poor health, reduced cognitive development, lost economic productivity, and poverty in many parts of the world.
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Affiliation(s)
- Richard Walker
- Center for Vaccine Innovation and Access, PATH, Washington, DC 20001, USA;
| | - Robert W. Kaminski
- Department of Diarrheal Disease Research, Walter Reed Institute of Research, Silver Spring, MD 20910, USA;
| | - Chad Porter
- Enteric Diseases Department, Naval Medical Research Center, Silver Spring, MD 20910, USA;
| | - Robert K. M. Choy
- Center for Vaccine Innovation and Access, PATH, San Francisco, CA 94108, USA;
| | - Jessica A. White
- Center for Vaccine Innovation and Access, PATH, Seattle, WA 98121, USA; (J.A.W.); (F.C.)
| | - James M. Fleckenstein
- Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA;
- Medicine Service, Saint Louis VA Health Care System, St. Louis, MO 63106, USA
| | - Fred Cassels
- Center for Vaccine Innovation and Access, PATH, Seattle, WA 98121, USA; (J.A.W.); (F.C.)
| | - Louis Bourgeois
- Center for Vaccine Innovation and Access, PATH, Washington, DC 20001, USA;
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12
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Richards A, Baranova DE, Pizzuto MS, Jaconi S, Willsey GG, Torres-Velez FJ, Doering JE, Benigni F, Corti D, Mantis NJ. Recombinant Human Secretory IgA Induces Salmonella Typhimurium Agglutination and Limits Bacterial Invasion into Gut-Associated Lymphoid Tissues. ACS Infect Dis 2021; 7:1221-1235. [PMID: 33728898 PMCID: PMC8154420 DOI: 10.1021/acsinfecdis.0c00842] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Indexed: 12/11/2022]
Abstract
As the predominant antibody type in mucosal secretions, human colostrum, and breast milk, secretory IgA (SIgA) plays a central role in safeguarding the intestinal epithelium of newborns from invasive enteric pathogens like the Gram-negative bacterium Salmonella enterica serovar Typhimurium (STm). SIgA is a complex molecule, consisting of an assemblage of two or more IgA monomers, joining (J)-chain, and secretory component (SC), whose exact functions in neutralizing pathogens are only beginning to be elucidated. In this study, we produced and characterized a recombinant human SIgA variant of Sal4, a well-characterized monoclonal antibody (mAb) specific for the O5-antigen of STm lipopolysaccharide (LPS). We demonstrate by flow cytometry, light microscopy, and fluorescence microscopy that Sal4 SIgA promotes the formation of large, densely packed bacterial aggregates in vitro. In a mouse model, passive oral administration of Sal4 SIgA was sufficient to entrap STm within the intestinal lumen and reduce bacterial invasion into gut-associated lymphoid tissues by several orders of magnitude. Bacterial aggregates induced by Sal4 SIgA treatment in the intestinal lumen were recalcitrant to immunohistochemical staining, suggesting the bacteria were encased in a protective capsule. Indeed, a crystal violet staining assay demonstrated that STm secretes an extracellular matrix enriched in cellulose following even short exposures to Sal4 SIgA. Collectively, these results demonstrate that recombinant human SIgA recapitulates key biological activities associated with mucosal immunity and raises the prospect of oral passive immunization to combat enteric diseases.
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Affiliation(s)
- Angelene
F. Richards
- Department
of Biomedical Sciences, University at Albany
School of Public Health, Albany, New York 12208, United States
- Division
of Infectious Diseases, Wadsworth Center,
New York State Department of Health, Albany, New York 12208, United States
| | - Danielle E. Baranova
- Division
of Infectious Diseases, Wadsworth Center,
New York State Department of Health, Albany, New York 12208, United States
| | - Matteo S. Pizzuto
- Humabs
BioMed SA a Subsidiary of Vir Biotechnology Inc., 6500 Bellinzona, Switzerland
| | - Stefano Jaconi
- Humabs
BioMed SA a Subsidiary of Vir Biotechnology Inc., 6500 Bellinzona, Switzerland
| | - Graham G. Willsey
- Division
of Infectious Diseases, Wadsworth Center,
New York State Department of Health, Albany, New York 12208, United States
| | - Fernando J. Torres-Velez
- Division
of Infectious Diseases, Wadsworth Center,
New York State Department of Health, Albany, New York 12208, United States
| | - Jennifer E. Doering
- Division
of Infectious Diseases, Wadsworth Center,
New York State Department of Health, Albany, New York 12208, United States
| | - Fabio Benigni
- Humabs
BioMed SA a Subsidiary of Vir Biotechnology Inc., 6500 Bellinzona, Switzerland
| | - Davide Corti
- Humabs
BioMed SA a Subsidiary of Vir Biotechnology Inc., 6500 Bellinzona, Switzerland
| | - Nicholas J. Mantis
- Department
of Biomedical Sciences, University at Albany
School of Public Health, Albany, New York 12208, United States
- Division
of Infectious Diseases, Wadsworth Center,
New York State Department of Health, Albany, New York 12208, United States
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13
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Anti-CfaE nanobodies provide broad cross-protection against major pathogenic enterotoxigenic Escherichia coli strains, with implications for vaccine design. Sci Rep 2021; 11:2751. [PMID: 33531570 PMCID: PMC7854682 DOI: 10.1038/s41598-021-81895-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Accepted: 12/14/2020] [Indexed: 11/15/2022] Open
Abstract
Enterotoxigenic Escherichia coli (ETEC) is estimated to cause approximately 380,000 deaths annually during sporadic or epidemic outbreaks worldwide. Development of vaccines against ETEC is very challenging due to the vast heterogeneity of the ETEC strains. An effective vaccines would have to be multicomponent to provide coverage of over ten ETEC strains with genetic variabilities. There is currently no vaccine licensed to prevent ETEC. Nanobodies are successful new biologics in treating mucosal infectious disease as they recognize conserved epitopes on hypervariable pathogens. Cocktails consisting of multiple nanobodies could provide even broader epitope coverage at a lower cost compared to monoclonal antibodies. Identification of conserved epitopes by nanobodies can also assist reverse engineering of an effective vaccine against ETEC. By screening nanobodies from immunized llamas and a naïve yeast display library against adhesins of colonization factors, we identified single nanobodies that show cross-protective potency against eleven major pathogenic ETEC strains in vitro. Oral administration of nanobodies led to a significant reduction of bacterial colonization in animals. Moreover, nanobody-IgA fusion showed extended inhibitory activity in mouse colonization compared to commercial hyperimmune bovine colostrum product used for prevention of ETEC-induced diarrhea. Structural analysis revealed that nanobodies recognized a highly-conserved epitope within the putative receptor binding region of ETEC adhesins. Our findings support further rational design of a pan-ETEC vaccine to elicit robust immune responses targeting this conserved epitope.
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14
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Cross-Reactivity, Epitope Mapping, and Potency of Monoclonal Antibodies to Class 5 Fimbrial Tip Adhesins of Enterotoxigenic Escherichia coli. Infect Immun 2020; 88:IAI.00246-20. [PMID: 32839190 PMCID: PMC7573445 DOI: 10.1128/iai.00246-20] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Accepted: 08/08/2020] [Indexed: 12/26/2022] Open
Abstract
Enterotoxigenic Escherichia coli (ETEC) is a leading diarrheagenic bacterial pathogen among travelers and children in resource-limited regions. Adherence to host intestinal cells mediated by ETEC fimbriae is believed to be a critical first step in ETEC pathogenesis. These fimbriae are categorized into related classes based on sequence similarity, with members of the class 5 fimbrial family being the best characterized. The eight related members of the ETEC class 5 fimbrial family are subdivided into three subclasses (5a, 5b, and 5c) that share similar structural arrangements, including a fimbrial tip adhesin. Enterotoxigenic Escherichia coli (ETEC) is a leading diarrheagenic bacterial pathogen among travelers and children in resource-limited regions. Adherence to host intestinal cells mediated by ETEC fimbriae is believed to be a critical first step in ETEC pathogenesis. These fimbriae are categorized into related classes based on sequence similarity, with members of the class 5 fimbrial family being the best characterized. The eight related members of the ETEC class 5 fimbrial family are subdivided into three subclasses (5a, 5b, and 5c) that share similar structural arrangements, including a fimbrial tip adhesin. However, sequence variability among the class 5 adhesins may hinder the generation of cross-protective antibodies. To better understand functional epitopes of the class 5 adhesins and their ability to induce intraclass antibody responses, we produced 28 antiadhesin monoclonal antibodies (MAbs) to representative adhesins CfaE, CsbD, and CotD, respectively. We determined the MAb cross-reactivities, localized the epitopes, and measured functional activities as potency in inhibition of hemagglutination induced by class 5 fimbria-bearing ETEC. The MAbs’ reactivities to a panel of class 5 adhesins in enzyme-linked immunosorbent assays (ELISAs) revealed several reactivity patterns, including individual adhesin specificity, intrasubclass specificity, intersubclass specificity, and class-wide cross-reactivity, suggesting that some conserved epitopes, including two conserved arginines, are shared by the class 5 adhesins. However, the cross-reactive MAbs had functional activities limited to strains expressing colonization factor antigen I (CFA/I), coli surface antigen 17 (CS17), or CS1, suggesting that the breadth of functional activities of the MAbs was more restricted than the repertoire of cross-reactivities measured by ELISA. The results imply that multivalent adhesin-based ETEC vaccines or prophylactics need more than one active component to reach broad protection.
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15
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Riaz S, Steinsland H, Hanevik K. Human Mucosal IgA Immune Responses against Enterotoxigenic Escherichia coli. Pathogens 2020; 9:pathogens9090714. [PMID: 32872549 PMCID: PMC7558491 DOI: 10.3390/pathogens9090714] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Revised: 08/11/2020] [Accepted: 08/24/2020] [Indexed: 12/14/2022] Open
Abstract
Infection with enterotoxigenic Escherichia coli (ETEC) is a major contributor to diarrheal illness in children in low- and middle-income countries and travelers to these areas. There is an ongoing effort to develop vaccines against ETEC, and the most reliable immune correlate of protection against ETEC is considered to be the small intestinal secretory IgA response that targets ETEC-specific virulence factors. Since isolating IgA from small intestinal mucosa is technically and ethically challenging, requiring the use of invasive medical procedures, several other indirect methods are used as a proxy for gauging the small intestinal IgA responses. In this review, we summarize the literature reporting on anti-ETEC human IgA responses observed in blood, activated lymphocyte assayss, intestinal lavage/duodenal aspirates, and saliva from human volunteers being experimentally infected with ETEC. We describe the IgA response kinetics and responder ratios against classical and noncanonical ETEC antigens in the different sample types and discuss the implications that the results may have on vaccine development and testing.
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Affiliation(s)
- Saman Riaz
- Department of Clinical Science, University of Bergen, Jonas Lies veg 87, N-5021 Bergen, Norway;
- Centre for International Health, Department of Global Public Health and Primary Care, University of Bergen, 5020 Bergen, Norway
| | - Hans Steinsland
- Centre for Intervention Science in Maternal and Child Health, Centre for International Health, Department of Global Public Health and Primary Care, University of Bergen, 5020 Bergen, Norway;
- Department of Biomedicine, University of Bergen, 5020 Bergen, Norway
| | - Kurt Hanevik
- Department of Clinical Science, University of Bergen, Jonas Lies veg 87, N-5021 Bergen, Norway;
- Norwegian National Advisory Unit on Tropical Infectious Diseases, Department of Medicine, Haukeland University Hospital, 5021 Bergen, Norway
- Correspondence: ; Tel.: +47-5597-5000; Fax: +47-5597-2950
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16
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Ejemel M, Li Q, Hou S, Schiller ZA, Tree JA, Wallace A, Amcheslavsky A, Kurt Yilmaz N, Buttigieg KR, Elmore MJ, Godwin K, Coombes N, Toomey JR, Schneider R, Ramchetty AS, Close BJ, Chen DY, Conway HL, Saeed M, Ganesa C, Carroll MW, Cavacini LA, Klempner MS, Schiffer CA, Wang Y. A cross-reactive human IgA monoclonal antibody blocks SARS-CoV-2 spike-ACE2 interaction. Nat Commun 2020; 11:4198. [PMID: 32826914 PMCID: PMC7442812 DOI: 10.1038/s41467-020-18058-8] [Citation(s) in RCA: 108] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Accepted: 08/03/2020] [Indexed: 01/19/2023] Open
Abstract
COVID-19 caused by SARS-CoV-2 has become a global pandemic requiring the development of interventions for the prevention or treatment to curtail mortality and morbidity. No vaccine to boost mucosal immunity, or as a therapeutic, has yet been developed to SARS-CoV-2. In this study, we discover and characterize a cross-reactive human IgA monoclonal antibody, MAb362. MAb362 binds to both SARS-CoV and SARS-CoV-2 spike proteins and competitively blocks ACE2 receptor binding, by overlapping the ACE2 structural binding epitope. Furthermore, MAb362 IgA neutralizes both pseudotyped SARS-CoV and SARS-CoV-2 in 293 cells expressing ACE2. When converted to secretory IgA, MAb326 also neutralizes authentic SARS-CoV-2 virus while the IgG isotype shows no neutralization. Our results suggest that SARS-CoV-2 specific IgA antibodies, such as MAb362, may provide effective immunity against SARS-CoV-2 by inducing mucosal immunity within the respiratory system, a potentially critical feature of an effective vaccine. Here, Ejemel et al. report the identification and characterization of a cross-neutralizing human IgA monoclonal antibody, named MAb362, that binds the receptor-binding domain of SARS-CoV-2 Spike, blocking its interaction with the ACE2 host receptor.
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Affiliation(s)
- Monir Ejemel
- MassBiologics of the University of Massachusetts Medical School, Boston, MA, USA
| | - Qi Li
- MassBiologics of the University of Massachusetts Medical School, Boston, MA, USA
| | - Shurong Hou
- Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Boston, MA, USA
| | - Zachary A Schiller
- MassBiologics of the University of Massachusetts Medical School, Boston, MA, USA
| | - Julia A Tree
- National Infection Service, Public Health England, Porton Down, Salisbury, Wiltshire, UK
| | - Aaron Wallace
- MassBiologics of the University of Massachusetts Medical School, Boston, MA, USA
| | - Alla Amcheslavsky
- MassBiologics of the University of Massachusetts Medical School, Boston, MA, USA
| | - Nese Kurt Yilmaz
- Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Boston, MA, USA
| | - Karen R Buttigieg
- National Infection Service, Public Health England, Porton Down, Salisbury, Wiltshire, UK
| | - Michael J Elmore
- National Infection Service, Public Health England, Porton Down, Salisbury, Wiltshire, UK
| | - Kerry Godwin
- National Infection Service, Public Health England, Porton Down, Salisbury, Wiltshire, UK
| | - Naomi Coombes
- National Infection Service, Public Health England, Porton Down, Salisbury, Wiltshire, UK
| | - Jacqueline R Toomey
- MassBiologics of the University of Massachusetts Medical School, Boston, MA, USA
| | - Ryan Schneider
- MassBiologics of the University of Massachusetts Medical School, Boston, MA, USA
| | - Anudeep S Ramchetty
- MassBiologics of the University of Massachusetts Medical School, Boston, MA, USA
| | - Brianna J Close
- National Emerging Infectious Diseases Laboratories, Boston University, Boston, MA, USA
| | - Da-Yuan Chen
- National Emerging Infectious Diseases Laboratories, Boston University, Boston, MA, USA
| | - Hasahn L Conway
- National Emerging Infectious Diseases Laboratories, Boston University, Boston, MA, USA
| | - Mohsan Saeed
- National Emerging Infectious Diseases Laboratories, Boston University, Boston, MA, USA
| | - Chandrashekar Ganesa
- MassBiologics of the University of Massachusetts Medical School, Boston, MA, USA
| | - Miles W Carroll
- National Infection Service, Public Health England, Porton Down, Salisbury, Wiltshire, UK
| | - Lisa A Cavacini
- MassBiologics of the University of Massachusetts Medical School, Boston, MA, USA.
| | - Mark S Klempner
- MassBiologics of the University of Massachusetts Medical School, Boston, MA, USA.
| | - Celia A Schiffer
- Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Boston, MA, USA.
| | - Yang Wang
- MassBiologics of the University of Massachusetts Medical School, Boston, MA, USA.
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17
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Ejemel M, Li Q, Hou S, Schiller ZA, Wallace AL, Amcheslavsky A, Yilmaz NK, Toomey JR, Schneider R, Close BJ, Chen DY, Conway HL, Mohsan S, Cavacini LA, Klempner MS, Schiffer CA, Wang Y. IgA MAb blocks SARS-CoV-2 Spike-ACE2 interaction providing mucosal immunity. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2020. [PMID: 32511396 DOI: 10.1101/2020.05.15.096719] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
COVID-19 caused by SARS-CoV-2 has become a global pandemic requiring the development of interventions for the prevention or treatment to curtail mortality and morbidity. No vaccine to boost mucosal immunity or as a therapeutic has yet been developed to SARS-CoV-2. In this study we discover and characterize a cross-reactive human IgA monoclonal antibody, MAb362. MAb362 binds to both SARS-CoV and SARS-CoV-2 spike proteins and competitively blocks hACE2 receptor binding, by completely overlapping the hACE2 structural binding epitope. Furthermore, MAb362 IgA neutralizes both pseudotyped SARS-CoV and SARS-CoV-2 in human epithelial cells expressing hACE2. SARS-CoV-2 specific IgA antibodies, such as MAb362, may provide effective immunity against SARS-CoV-2 by inducing mucosal immunity within the respiratory system, a potentially critical feature of an effective vaccine.
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