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Vickers TJ, Buckley DP, Khatoon N, Sheikh A, Setu B, Berndsen ZT, Fleckenstein JM. Parenteral vaccination with recombinant EtpA glycoprotein impairs enterotoxigenic E. coli colonization. Infect Immun 2025; 93:e0060124. [PMID: 40310293 DOI: 10.1128/iai.00601-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2024] [Accepted: 03/05/2025] [Indexed: 05/02/2025] Open
Abstract
Enterotoxigenic E. coli (ETEC) causes hundreds of millions of cases of acute diarrheal illness in low- and middle-income regions, disproportionately in young children. To date, there is no licensed, broadly protective vaccine against these common but antigenically heterogeneous pathogens. One of the more highly conserved antigens of ETEC, EtpA, is an extracellular glycoprotein adhesin that preferentially binds to A blood group glycans on intestinal epithelia. EtpA contributes to increased severity of illness in A blood group individuals, elicits robust serologic and fecal antibody responses following infection, and has been associated with protection against subsequent infection. However, its utility as a protective antigen needs further examination. In the present studies, we examined whether parenteral vaccination with recombinant EtpA (rEtpA) could afford protection against intestinal colonization in a murine model of ETEC infection. Here, we demonstrate that intramuscular vaccination with rEtpA, adjuvanted with double mutant LT (dmLT), primes IgG predominant mucosal antibody responses to ETEC challenge. Notably, however, both antibody levels and avidity, as well as protection, were dependent on the vaccination schedule. Likewise, through electron microscopy polyclonal epitope mapping (EMPEM), we observed a different repertoire of epitopes targeted by antibodies after a more protracted vaccination schedule. Next, we explored the utility of IM immunization with alum-adjuvanted rEtpA. This elicited strong serologic and fecal IgG responses. Although accompanied by negligible IgA mucosal responses, EtpA alum-adjuvanted IM vaccination nevertheless protected against ETEC intestinal colonization. Collectively, these data suggest that EtpA could expand the portfolio of antigens targeted in ETEC subunit vaccine development.
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Affiliation(s)
- Tim J Vickers
- Division of Infectious Diseases, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - David P Buckley
- Department of Biochemistry, University of Missouri Columbia, Columbia, Missouri, USA
| | - Nazia Khatoon
- Division of Infectious Diseases, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Alaullah Sheikh
- Division of Infectious Diseases, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Bipul Setu
- Division of Infectious Diseases, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Zachary T Berndsen
- Department of Biochemistry, University of Missouri Columbia, Columbia, Missouri, USA
| | - James M Fleckenstein
- Division of Infectious Diseases, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
- Infectious Diseases, Medicine Service, Veterans Affairs Saint Louis Health Care System, St. Louis, Missouri, USA
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Gutiérrez RL, Porter CK, Harro C, Talaat K, Riddle MS, DeNearing B, Brubaker J, Maciel M, Laird RM, Poole S, Chakraborty S, Maier N, Sack DA, Savarino SJ. Efficacy Evaluation of an Intradermally Delivered Enterotoxigenic Escherichia coli CF Antigen I Fimbrial Tip Adhesin Vaccine Coadministered with Heat-Labile Enterotoxin with LT(R192G) against Experimental Challenge with Enterotoxigenic E. coli H10407 in Healthy Adult Volunteers. Microorganisms 2024; 12:288. [PMID: 38399692 PMCID: PMC10892241 DOI: 10.3390/microorganisms12020288] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Revised: 01/16/2024] [Accepted: 01/26/2024] [Indexed: 02/25/2024] Open
Abstract
BACKGROUND Enterotoxigenic E. coli (ETEC) is a principal cause of diarrhea in travelers, deployed military personnel, and children living in low to middle-income countries. ETEC expresses a variety of virulence factors including colonization factors (CF) that facilitate adherence to the intestinal mucosa. We assessed the protective efficacy of a tip-localized subunit of CF antigen I (CFA/I), CfaE, delivered intradermally with the mutant E. coli heat-labile enterotoxin, LTR192G, in a controlled human infection model (CHIM). METHODS Three cohorts of healthy adult subjects were enrolled and given three doses of 25 μg CfaE + 100 ng LTR192G vaccine intradermally at 3-week intervals. Approximately 28 days after the last vaccination, vaccinated and unvaccinated subjects were admitted as inpatients and challenged with approximately 2 × 107 cfu of CFA/I+ ETEC strain H10407 following an overnight fast. Subjects were assessed for moderate-to-severe diarrhea for 5 days post-challenge. RESULTS A total of 52 volunteers received all three vaccinations; 41 vaccinated and 43 unvaccinated subjects were challenged and assessed for moderate-to-severe diarrhea. Naïve attack rates varied from 45.5% to 64.7% across the cohorts yielding an overall efficacy estimate of 27.8% (95% confidence intervals: -7.5-51.6%). In addition to reducing moderate-severe diarrhea rates, the vaccine significantly reduced loose stool output and overall ETEC disease severity. CONCLUSIONS This is the first study to demonstrate protection against ETEC challenge after intradermal vaccination with an ETEC adhesin. Further examination of the challenge methodology is necessary to address the variability in naïve attack rate observed among the three cohorts in the present study.
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Affiliation(s)
- Ramiro L. Gutiérrez
- Naval Medical Research Command, Silver Spring, MD 20910, USA; (R.L.G.); (M.S.R.); (R.M.L.); (S.P.); (S.J.S.)
| | - Chad K. Porter
- Naval Medical Research Command, Silver Spring, MD 20910, USA; (R.L.G.); (M.S.R.); (R.M.L.); (S.P.); (S.J.S.)
| | - Clayton Harro
- Center for Immunization Research, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21224, USA (K.T.); (B.D.); (D.A.S.)
| | - Kawsar Talaat
- Center for Immunization Research, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21224, USA (K.T.); (B.D.); (D.A.S.)
| | - Mark S. Riddle
- Naval Medical Research Command, Silver Spring, MD 20910, USA; (R.L.G.); (M.S.R.); (R.M.L.); (S.P.); (S.J.S.)
| | - Barbara DeNearing
- Center for Immunization Research, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21224, USA (K.T.); (B.D.); (D.A.S.)
| | - Jessica Brubaker
- Center for Immunization Research, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21224, USA (K.T.); (B.D.); (D.A.S.)
| | - Milton Maciel
- Naval Medical Research Command, Silver Spring, MD 20910, USA; (R.L.G.); (M.S.R.); (R.M.L.); (S.P.); (S.J.S.)
- Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, MD 20817, USA
| | - Renee M. Laird
- Naval Medical Research Command, Silver Spring, MD 20910, USA; (R.L.G.); (M.S.R.); (R.M.L.); (S.P.); (S.J.S.)
- Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, MD 20817, USA
| | - Steven Poole
- Naval Medical Research Command, Silver Spring, MD 20910, USA; (R.L.G.); (M.S.R.); (R.M.L.); (S.P.); (S.J.S.)
- Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, MD 20817, USA
| | - Subra Chakraborty
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA;
| | | | - David A. Sack
- Center for Immunization Research, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21224, USA (K.T.); (B.D.); (D.A.S.)
| | - Stephen J. Savarino
- Naval Medical Research Command, Silver Spring, MD 20910, USA; (R.L.G.); (M.S.R.); (R.M.L.); (S.P.); (S.J.S.)
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Zhou S, Yu KOA, Mabrouk MT, Jahagirdar D, Huang WC, Guerra JA, He X, Ortega J, Poole ST, Hall ER, Gomez-Duarte OG, Maciel M, Lovell JF. Antibody induction in mice by liposome-displayed recombinant enterotoxigenic Escherichia coli (ETEC) colonization antigens. Biomed J 2023; 46:100588. [PMID: 36925108 PMCID: PMC10711177 DOI: 10.1016/j.bj.2023.03.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Revised: 03/03/2023] [Accepted: 03/06/2023] [Indexed: 03/17/2023] Open
Abstract
BACKGROUND Enterotoxigenic Escherichia coli (ETEC) strains cause infectious diarrhea and colonize host intestine epithelia via surface-expressed colonization factors. Colonization factor antigen I (CFA/I), a prevalent ETEC colonization factor, is a vaccine target since antibodies directed to this fimbria can block ETEC adherence and prevent diarrhea. METHODS Two recombinant antigens derived from CFA/I were investigated with a vaccine adjuvant system that displays soluble antigens on the surface of immunogenic liposomes. The first antigen, CfaEB, is a chimeric fusion protein comprising the minor (CfaE) and major (CfaB) subunits of CFA/I. The second, CfaEad, is the adhesin domain of CfaE. RESULTS Owing to their His-tag, recombinant CfaEB and CfaEad, spontaneously bound upon admixture with nanoliposomes containing cobalt-porphyrin phospholipid (CoPoP), as well as a synthetic monophosphoryl lipid A (PHAD) adjuvant. Intramuscular immunization of mice with sub-microgram doses CfaEB or CfaEad admixed with CoPoP/PHAD liposomes elicited serum IgG and intestinal IgA antibodies. The smaller CfaEad antigen benefitted more from liposome display. Serum and intestine antibodies from mice immunized with liposome-displayed CfaEB or CfaEad recognized native CFA/I fimbria as evidenced by immunofluorescence and hemagglutination inhibition assays using the CFA/I-expressing H10407 ETEC strain. CONCLUSION These data show that colonization factor-derived recombinant ETEC antigens exhibit immunogenicity when delivered in immunogenic particle-based formulations.
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Affiliation(s)
- Shiqi Zhou
- Department of Biomedical Engineering, State University of New York at Buffalo, Buffalo, NY, USA
| | - Karl O A Yu
- Division of Pediatrics Infectious Diseases, Department of Pediatrics, University at Buffalo, Buffalo, NY, USA
| | - Moustafa T Mabrouk
- Department of Biomedical Engineering, State University of New York at Buffalo, Buffalo, NY, USA
| | | | - Wei-Chiao Huang
- Department of Biomedical Engineering, State University of New York at Buffalo, Buffalo, NY, USA
| | - Julio A Guerra
- Division of Pediatrics Infectious Diseases, Department of Pediatrics, University at Buffalo, Buffalo, NY, USA
| | - Xuedan He
- Department of Biomedical Engineering, State University of New York at Buffalo, Buffalo, NY, USA
| | - Joaquin Ortega
- Department of Anatomy and Cell Biology, McGill University, Montreal, Canada
| | - Steven T Poole
- Naval Medical Research Center, Silver Spring, MD, USA; Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, MD, USA
| | - Eric R Hall
- Naval Medical Research Center, Silver Spring, MD, USA
| | - Oscar G Gomez-Duarte
- Division of Pediatrics Infectious Diseases, Department of Pediatrics, University at Buffalo, Buffalo, NY, USA
| | - Milton Maciel
- Naval Medical Research Center, Silver Spring, MD, USA; Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, MD, USA; Department of Microbiology and Immunology, Uniformed Services University Health System, Bethesda, MD, USA.
| | - Jonathan F Lovell
- Department of Biomedical Engineering, State University of New York at Buffalo, Buffalo, NY, USA.
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Crothers JW, Norton EB. Recent advances in enterotoxin vaccine adjuvants. Curr Opin Immunol 2023; 85:102398. [PMID: 37976963 PMCID: PMC11258862 DOI: 10.1016/j.coi.2023.102398] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Revised: 07/21/2023] [Accepted: 10/18/2023] [Indexed: 11/19/2023]
Abstract
Enterotoxin adjuvants have been researched for their ability to promote immunity to co-delivered antigens. Outside of cholera vaccines, however, these proteins have yet to be included in any currently licensed vaccines. They include molecules derived from the bacterial toxins of Vibrio cholerae, cholera toxin, or Escherichia coli, heat-labile toxin, such as detoxified mutants or subunits. This class of adjuvants is distinguished by their delivery possibilities, which include parenteral injection, skin applications, or direct mucosal administration by oral, sublingual, or nasal routes. In addition, inclusion of an enterotoxin adjuvant is associated with development of multifaceted cellular and humoral immune responses to vaccination. Here, we review exciting progress in the past few years in clinical trials for safety and efficacy, preclinical vaccines studies, and new mechanistic insights for enterotoxin adjuvants. This includes recent reports of their use in vaccines targeting microbial infections (bacterial, viral, parasitic) or substance abuse drugs.
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Affiliation(s)
- Jessica W Crothers
- Department of Pathology and Laboratory Medicine, University of Vermont Larner College of Medicine, Burlington, VT, USA
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Lykins WR, Fox CB. Practical Considerations for Next-Generation Adjuvant Development and Translation. Pharmaceutics 2023; 15:1850. [PMID: 37514037 PMCID: PMC10385070 DOI: 10.3390/pharmaceutics15071850] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Revised: 06/21/2023] [Accepted: 06/27/2023] [Indexed: 07/30/2023] Open
Abstract
Over the last several years, there has been increased interest from academia and the pharmaceutical/biotech industry in the development of vaccine adjuvants for new and emerging vaccine modalities. Despite this, vaccine adjuvant development still has some of the longest timelines in the pharmaceutical space, from discovery to clinical approval. The reasons for this are manyfold and range from complexities in translation from animal to human models, concerns about safety or reactogenicity, to challenges in sourcing the necessary raw materials at scale. In this review, we will describe the current state of the art for many adjuvant technologies and how they should be approached or applied in the development of new vaccine products. We postulate that there are many factors to be considered and tools to be applied earlier on in the vaccine development pipeline to improve the likelihood of clinical success. These recommendations may require a modified approach to some of the common practices in new product development but would result in more accessible and practical adjuvant-containing products.
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Fisher KJ, Kinsey R, Mohamath R, Phan T, Liang H, Orr MT, Lykins WR, Guderian JA, Bakken J, Argilla D, Ramer-Denisoff G, Larson E, Qi Y, Sivananthan S, Smolyar K, Carter D, Paddon CJ, Fox CB. Semi-synthetic terpenoids with differential adjuvant properties as sustainable replacements for shark squalene in vaccine emulsions. NPJ Vaccines 2023; 8:14. [PMID: 36797262 PMCID: PMC9935550 DOI: 10.1038/s41541-023-00608-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Accepted: 01/24/2023] [Indexed: 02/18/2023] Open
Abstract
Synthetic biology has allowed for the industrial production of supply-limited sesquiterpenoids such as the antimalarial drug artemisinin and β-farnesene. One of the only unmodified animal products used in medicine is squalene, a triterpenoid derived from shark liver oil, which when formulated into an emulsion is used as a vaccine adjuvant to enhance immune responses in licensed vaccines. However, overfishing is depleting deep-sea shark populations, leading to potential supply problems for squalene. We chemically generated over 20 squalene analogues from fermentation-derived β-farnesene and evaluated adjuvant activity of the emulsified compounds compared to shark squalene emulsion. By employing a desirability function approach that incorporated multiple immune readouts, we identified analogues with enhanced, equivalent, or decreased adjuvant activity compared to shark squalene emulsion. Availability of a library of structurally related analogues allowed elucidation of structure-function relationships. Thus, combining industrial synthetic biology with chemistry and immunology enabled generation of sustainable terpenoid-based vaccine adjuvants comparable to current shark squalene-based adjuvants while illuminating structural properties important for adjuvant activity.
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Affiliation(s)
| | - Robert Kinsey
- Access to Advanced Health Institute, formerly Infectious Disease Research Institute, Seattle, WA, USA
| | - Raodoh Mohamath
- Access to Advanced Health Institute, formerly Infectious Disease Research Institute, Seattle, WA, USA
| | - Tony Phan
- Infectious Disease Research Institute, Seattle, WA, USA
- Neoleukin, Seattle, WA, USA
| | - Hong Liang
- Infectious Disease Research Institute, Seattle, WA, USA
- Bristol-Myers Squibb, Seattle, WA, USA
| | - Mark T Orr
- Infectious Disease Research Institute, Seattle, WA, USA
- Bristol-Myers Squibb, Seattle, WA, USA
| | - William R Lykins
- Access to Advanced Health Institute, formerly Infectious Disease Research Institute, Seattle, WA, USA
| | - Jeffrey A Guderian
- Access to Advanced Health Institute, formerly Infectious Disease Research Institute, Seattle, WA, USA
| | - Julie Bakken
- Access to Advanced Health Institute, formerly Infectious Disease Research Institute, Seattle, WA, USA
| | - David Argilla
- Access to Advanced Health Institute, formerly Infectious Disease Research Institute, Seattle, WA, USA
| | - Gabi Ramer-Denisoff
- Access to Advanced Health Institute, formerly Infectious Disease Research Institute, Seattle, WA, USA
| | - Elise Larson
- Access to Advanced Health Institute, formerly Infectious Disease Research Institute, Seattle, WA, USA
| | - Yizhi Qi
- Access to Advanced Health Institute, formerly Infectious Disease Research Institute, Seattle, WA, USA
| | - Sandra Sivananthan
- Access to Advanced Health Institute, formerly Infectious Disease Research Institute, Seattle, WA, USA
| | | | - Darrick Carter
- Infectious Disease Research Institute, Seattle, WA, USA
- HDT Bio Corp., Seattle, WA, USA
- PAI Life Sciences Inc., Seattle, WA, USA
| | | | - Christopher B Fox
- Access to Advanced Health Institute, formerly Infectious Disease Research Institute, Seattle, WA, USA.
- Department of Global Health, University of Washington, Seattle, WA, USA.
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Tobuse AJ, Ang CW, Yeong KY. Modern vaccine development via reverse vaccinology to combat antimicrobial resistance. Life Sci 2022; 302:120660. [PMID: 35642852 DOI: 10.1016/j.lfs.2022.120660] [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: 03/25/2022] [Revised: 05/02/2022] [Accepted: 05/19/2022] [Indexed: 10/18/2022]
Abstract
With the continuous evolution of bacteria, the global antimicrobial resistance health threat is causing millions of deaths yearly. While depending on antibiotics as a primary treatment has its merits, there are no effective alternatives thus far in the pharmaceutical market against some drug-resistant bacteria. In recent years, vaccinology has become a key topic in scientific research. Combining with the growth of technology, vaccine research is seeing a new light where the process is made faster and more efficient. Although less discussed, bacterial vaccine is a feasible strategy to combat antimicrobial resistance. Some vaccines have shown promising results with good efficacy against numerous multidrug-resistant strains of bacteria. In this review, we aim to discuss the findings from studies utilizing reverse vaccinology for vaccine development against some multidrug-resistant bacteria, as well as provide a summary of multi-year bacterial vaccine studies in clinical trials. The advantages of reverse vaccinology in the generation of new bacterial vaccines are also highlighted. Meanwhile, the limitations and future prospects of bacterial vaccine concludes this review.
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Affiliation(s)
- Asuka Joy Tobuse
- School of Science, Monash University Malaysia Campus, Jalan Lagoon Selatan, Bandar Sunway 47500, Selangor, Malaysia
| | - Chee Wei Ang
- School of Science, Monash University Malaysia Campus, Jalan Lagoon Selatan, Bandar Sunway 47500, Selangor, Malaysia
| | - Keng Yoon Yeong
- School of Science, Monash University Malaysia Campus, Jalan Lagoon Selatan, Bandar Sunway 47500, Selangor, Malaysia.
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Sun Y, Huang L, Nie J, Feng K, Liu Y, Bai Z. Development of a perfusion process for serum-free adenovirus vector herpes zoster vaccine production. AMB Express 2022; 12:58. [PMID: 35567723 PMCID: PMC9107214 DOI: 10.1186/s13568-022-01398-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Accepted: 05/04/2022] [Indexed: 11/10/2022] Open
Abstract
Herpes zoster is caused by reactivation of the varicella zoster virus (VZV). Researching and developing a herpes zoster vaccine will help to decrease the incidence of herpes zoster. To increase the bioreactor productivity, a serum-free HEK293 cell perfusion process with adenovirus vector herpes zoster (rAd-HZ) vaccine production was developed efficiently using the design of experiment (DoE) method. First, serum-free media for HEK293 cells were screened in both batch and semi-perfusion culture modes. Then, three optimal media were employed in a medium mixture design to improve cell culture performance, and the 1:1 mixture of HEK293 medium and MCD293 medium (named HM293 medium) was identified as the optimal formulation. On the basis of the HM293 medium, the relationship of critical process parameters (CPPs), including the time of infection (TOI), multiplicity of infection (MOI), pH, and critical quality attributes (CQAs) (adenovirus titer (Titer), cell-specific virus yield (CSVY), adenovirus fold expansion (Fold)) of rAd-HZ production was investigated using the DoE approach. Furthermore, the robust setpoint and design space of these CPPs were explored. Finally, the rAd-HZ production process with parameters at a robust setpoint (TOI = 7.2 × 106 cells/mL, MOI = 3.7, and pH = 7.17) was successfully scaled-up to a 3-L bioreactor with an alternating tangential flow system, yielding an adenovirus titer of 3.0 × 1010 IFU/mL, a CSVY of 4167 IFU/cells, a Fold of 1117 at 2 days post infection (dpi). The DoE approach accelerated the development of a HEK293 serum-free medium and of a robust adenovirus production process.
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Fleckenstein JM. Confronting challenges to enterotoxigenic Escherichia coli vaccine development. FRONTIERS IN TROPICAL DISEASES 2021; 2:709907. [PMID: 35937717 PMCID: PMC9355458 DOI: 10.3389/fitd.2021.709907] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/02/2023] Open
Abstract
The enterotoxigenic Escherichia coli (ETEC) are a diverse and genetically plastic pathologic variant (pathovar) of E. coli defined by their production of heat-labile (LT) and heat-stable (ST) enterotoxins. These pathogens, which came to recognition more than four decades ago in patients presenting with severe cholera-like diarrhea, are now known to cause hundreds of millions of cases of symptomatic infection annually. Children in low-middle income regions of the world lacking access to clean water and basic sanitation are disproportionately affected by ETEC. In addition to acute diarrheal morbidity, these pathogens remain a significant cause of mortality in children under the age of five years and have also been linked repeatedly to sequelae of childhood malnutrition and growth stunting. Vaccines that could prevent ETEC infections therefore remain a high priority. Despite several decades of effort, a licensed vaccine that protects against the breadth of these pathogens remains an aspirational goal, and the underlying genetic plasticity of E. coli has posed a fundamental challenge to development of a vaccine that can encompass the complete antigenic spectrum of ETEC. Nevertheless, novel strategies that include toxoids, a more complete understanding of ETEC molecular pathogenesis, structural details of target immunogens, and the discovery of more highly conserved antigens essential for virulence should accelerate progress and make a broadly protective vaccine feasible.
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Affiliation(s)
- James M. Fleckenstein
- Department of Medicine, Division of Infectious Diseases, Washington University in Saint Louis, School of Medicine, Saint Louis, Missouri, USA
- Medicine Service, Infectious Diseases, John Cochran Saint Louis Veterans Affairs Health Care System, Saint Louis, Missouri, USA
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10
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Abhyankar MM, Orr MT, Kinsey R, Sivananthan S, Nafziger AJ, Oakland DN, Young MK, Farr L, Uddin MJ, Leslie JL, Burgess SL, Liang H, De Lima I, Larson E, Guderian JA, Lin S, Kahn A, Ghosh P, Reed S, Tomai MA, Pedersen K, Petri WA, Fox CB. Optimizing a Multi-Component Intranasal Entamoeba Histolytica Vaccine Formulation Using a Design of Experiments Strategy. Front Immunol 2021; 12:683157. [PMID: 34248966 PMCID: PMC8268010 DOI: 10.3389/fimmu.2021.683157] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2021] [Accepted: 06/07/2021] [Indexed: 11/24/2022] Open
Abstract
Amebiasis is a neglected tropical disease caused by Entamoeba histolytica. Although the disease burden varies geographically, amebiasis is estimated to account for some 55,000 deaths and millions of infections globally per year. Children and travelers are among the groups with the greatest risk of infection. There are currently no licensed vaccines for prevention of amebiasis, although key immune correlates for protection have been proposed from observational studies in humans. We previously described the development of a liposomal adjuvant formulation containing two synthetic TLR ligands (GLA and 3M-052) that enhanced antigen-specific fecal IgA, serum IgG2a, a mixed IFNγ and IL-17A cytokine profile from splenocytes, and protective efficacy following intranasal administration with the LecA antigen. By applying a statistical design of experiments (DOE) and desirability function approach, we now describe the optimization of the dose of each vaccine formulation component (LecA, GLA, 3M-052, and liposome) as well as the excipient composition (acyl chain length and saturation; PEGylated lipid:phospholipid ratio; and presence of antioxidant, tonicity, or viscosity agents) to maximize desired immunogenicity characteristics while maintaining physicochemical stability. This DOE/desirability index approach led to the identification of a lead candidate composition that demonstrated immune response durability and protective efficacy in the mouse model, as well as an assessment of the impact of each active vaccine formulation component on protection. Thus, we demonstrate that both GLA and 3M-052 are required for statistically significant protective efficacy. We also show that immunogenicity and efficacy results differ in female vs male mice, and the differences appear to be at least partly associated with adjuvant formulation composition.
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Affiliation(s)
- Mayuresh M Abhyankar
- Division of Infectious Diseases and International Health, Department of Medicine, University of Virginia Health System, Charlottesville, VA, United States
| | - Mark T Orr
- Infectious Disease Research Institute (IDRI), Seattle, WA, United States.,Department of Global Health, University of Washington, Seattle, WA, United States
| | - Robert Kinsey
- Infectious Disease Research Institute (IDRI), Seattle, WA, United States
| | - Sandra Sivananthan
- Infectious Disease Research Institute (IDRI), Seattle, WA, United States
| | - Andrew J Nafziger
- Division of Infectious Diseases and International Health, Department of Medicine, University of Virginia Health System, Charlottesville, VA, United States
| | - David N Oakland
- Division of Infectious Diseases and International Health, Department of Medicine, University of Virginia Health System, Charlottesville, VA, United States
| | - Mary K Young
- Division of Infectious Diseases and International Health, Department of Medicine, University of Virginia Health System, Charlottesville, VA, United States
| | - Laura Farr
- Division of Infectious Diseases and International Health, Department of Medicine, University of Virginia Health System, Charlottesville, VA, United States
| | - Md Jashim Uddin
- Division of Infectious Diseases and International Health, Department of Medicine, University of Virginia Health System, Charlottesville, VA, United States
| | - Jhansi L Leslie
- Division of Infectious Diseases and International Health, Department of Medicine, University of Virginia Health System, Charlottesville, VA, United States
| | - Stacey L Burgess
- Division of Infectious Diseases and International Health, Department of Medicine, University of Virginia Health System, Charlottesville, VA, United States
| | - Hong Liang
- Infectious Disease Research Institute (IDRI), Seattle, WA, United States
| | - Ines De Lima
- Infectious Disease Research Institute (IDRI), Seattle, WA, United States
| | - Elise Larson
- Infectious Disease Research Institute (IDRI), Seattle, WA, United States
| | - Jeffrey A Guderian
- Infectious Disease Research Institute (IDRI), Seattle, WA, United States
| | - Susan Lin
- Infectious Disease Research Institute (IDRI), Seattle, WA, United States
| | - Aaron Kahn
- Infectious Disease Research Institute (IDRI), Seattle, WA, United States
| | - Prakash Ghosh
- Infectious Disease Research Institute (IDRI), Seattle, WA, United States
| | - Sierra Reed
- Infectious Disease Research Institute (IDRI), Seattle, WA, United States
| | - Mark A Tomai
- 3M Corporate Research Materials Laboratory, 3M Center, St Paul, MN, United States
| | | | - William A Petri
- Division of Infectious Diseases and International Health, Department of Medicine, University of Virginia Health System, Charlottesville, VA, United States
| | - Christopher B Fox
- Infectious Disease Research Institute (IDRI), Seattle, WA, United States.,Department of Global Health, University of Washington, Seattle, WA, United States
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