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Acosta CJ, Nordio F, Boltz DA, Baldwin WR, Hather G, Kpamegan E. Predicting Efficacy of a Purified Inactivated Zika Virus Vaccine in Flavivirus-Naïve Humans Using an Immunological Correlate of Protection in Non-Human Primates. Microorganisms 2024; 12:1177. [PMID: 38930559 PMCID: PMC11206130 DOI: 10.3390/microorganisms12061177] [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: 05/15/2024] [Revised: 06/03/2024] [Accepted: 06/06/2024] [Indexed: 06/28/2024] Open
Abstract
A traditional phase 3 clinical efficacy study for a Zika vaccine may be unfeasible because of the current low transmission of Zika virus (ZIKV). An alternative clinical development approach to evaluate Zika vaccine efficacy (VE) is therefore required, delineated in the US FDA's Accelerated Approval Program for licensure, which utilizes an anti-Zika neutralizing antibody (Zika NAb) titer correlated with non-human primate (NHP) protection as a surrogate endpoint. In this accelerated approval approach, the estimation of VE would be inferred from the percentage of phase 3 trial participants achieving the established surrogate endpoint. We provide a statistical framework to predict the probability of protection for human participants vaccinated with a purified inactivated ZIKV vaccine (TAK-426), in the absence of VE measurements, using NHP data under a single-correlate model. Based on a logistic regression (LR) with bias-reduction model, a probability of 90% protection in humans is expected with a ZIKV NAb geometric mean titer (GMT) ≥ 3.38 log10 half-maximal effective concentration (EC50). The predicted probability of protection of TAK-426 against ZIKV infection was determined using the two-parameter LR model that fit the calculated VE in rhesus macaques and the flavivirus-naïve phase 1 trial participants' ZIKV NAb GMTs log10 EC50, measured by a ZIKV reporter virus particle assay, at 1 month post dose 2. The TAK-426 10 µg dose predicted a probability of protection from infection of 98% among flavivirus-naïve phase 1 trial participants.
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Affiliation(s)
- Camilo J. Acosta
- Takeda Vaccines Inc., Cambridge, MA 02142, USA; (F.N.); (D.A.B.); (W.R.B.); (G.H.); (E.K.)
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2
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Kim GL, Pyo SW, Yi H, Kim SH, Shin H, Yu MA, Hwang YR, Choi SY, Jeon JH, Jo SK, Rhie GE. Immunogenicity and Protective Efficacy of Recombinant Protective Antigen Anthrax Vaccine (GC1109) in A/J Mice Model. Vaccine 2023; 41:3106-3110. [PMID: 37055344 DOI: 10.1016/j.vaccine.2023.04.002] [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: 11/29/2022] [Revised: 02/10/2023] [Accepted: 04/03/2023] [Indexed: 04/15/2023]
Abstract
A recombinant protective antigen anthrax vaccine (GC1109) is being developed as a new-generation vaccine by the Korea Disease Control and Prevention Agency. In accordance with the ongoing step 2 of phase II clinical trials, the immunogenicity and protective efficacy of the booster dose of GC1109 were evaluated in A/J mice after 3 serial vaccinations at 4-week intervals. The results indicated that the booster dose significantly increased the production of anti-protective antigen (PA) IgG and toxin-neutralizing antibody (TNA) compared with those of the group without booster. An enhanced protective effect of the booster dose was not observed because the TNA titers of the group without booster were high enough to confer protection against spore challenge. Additionally, the correlation between TNA titers and probability of survival was determined for calculating the threshold TNA titer levels associated with protection. The threshold 50 % neutralization factor (NF50) of TNA showing 70 % probability of protection was 0.21 in A/J mice with 1,200 LD50 Sterne spores challenge. These results indicate that GC1109 is a promising candidate as a new-generation anthrax vaccine and that a booster dose might provide enhanced protection by producing toxin-neutralizing antibodies.
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Affiliation(s)
- Gyu-Lee Kim
- Division of High-risk Pathogens, Bureau of Infectious Disease Diagnosis Control, Korea Disease Control and Prevention Agency, Cheongju 28159, Republic of Korea
| | - Seong Wook Pyo
- Division of High-risk Pathogens, Bureau of Infectious Disease Diagnosis Control, Korea Disease Control and Prevention Agency, Cheongju 28159, Republic of Korea
| | - Hwajung Yi
- Division of High-risk Pathogens, Bureau of Infectious Disease Diagnosis Control, Korea Disease Control and Prevention Agency, Cheongju 28159, Republic of Korea
| | - So-Hyeon Kim
- Division of High-risk Pathogens, Bureau of Infectious Disease Diagnosis Control, Korea Disease Control and Prevention Agency, Cheongju 28159, Republic of Korea
| | - Hwachul Shin
- Division of High-risk Pathogens, Bureau of Infectious Disease Diagnosis Control, Korea Disease Control and Prevention Agency, Cheongju 28159, Republic of Korea
| | - Min-Ah Yu
- Division of High-risk Pathogens, Bureau of Infectious Disease Diagnosis Control, Korea Disease Control and Prevention Agency, Cheongju 28159, Republic of Korea
| | - Yi-Rang Hwang
- Division of High-risk Pathogens, Bureau of Infectious Disease Diagnosis Control, Korea Disease Control and Prevention Agency, Cheongju 28159, Republic of Korea
| | - Sang-Yoon Choi
- Division of High-risk Pathogens, Bureau of Infectious Disease Diagnosis Control, Korea Disease Control and Prevention Agency, Cheongju 28159, Republic of Korea
| | - Jun Ho Jeon
- Division of High-risk Pathogens, Bureau of Infectious Disease Diagnosis Control, Korea Disease Control and Prevention Agency, Cheongju 28159, Republic of Korea
| | - Su Kyoung Jo
- Division of High-risk Pathogens, Bureau of Infectious Disease Diagnosis Control, Korea Disease Control and Prevention Agency, Cheongju 28159, Republic of Korea
| | - Gi-Eun Rhie
- Division of High-risk Pathogens, Bureau of Infectious Disease Diagnosis Control, Korea Disease Control and Prevention Agency, Cheongju 28159, Republic of Korea.
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3
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Non-human primate to human immunobridging demonstrates a protective effect of Ad26.ZEBOV, MVA-BN-Filo vaccine against Ebola. NPJ Vaccines 2022; 7:156. [PMID: 36450746 PMCID: PMC9712521 DOI: 10.1038/s41541-022-00564-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Accepted: 10/21/2022] [Indexed: 12/05/2022] Open
Abstract
Without clinical efficacy data, vaccine protective effect may be extrapolated from animals to humans using an immunologic marker that correlates with protection in animals. This immunobridging approach was used for the two-dose Ebola vaccine regimen Ad26.ZEBOV, MVA-BN-Filo. Ebola virus (EBOV) glycoprotein binding antibody data obtained from 764 vaccinated healthy adults in five clinical studies (NCT02416453, NCT02564523, NCT02509494, NCT02543567, NCT02543268) were used to calculate mean predicted survival probability (with preplanned 95% confidence interval [CI]). We used a logistic regression model based on EBOV glycoprotein binding antibody responses in vaccinated non-human primates (NHPs) and NHP survival after EBOV challenge. While the protective effect of the vaccine regimen in humans can be inferred in this fashion, the extrapolated survival probability cannot be directly translated into vaccine efficacy. The primary immunobridging analysis evaluated the lower limit of the CI against predefined success criterion of 20% and passed with mean predicted survival probability of 53.4% (95% CI: 36.7-67.4).
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4
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Bridging Animal and Human Data in Pursuit of Vaccine Licensure. Vaccines (Basel) 2022; 10:vaccines10091384. [PMID: 36146462 PMCID: PMC9503666 DOI: 10.3390/vaccines10091384] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2022] [Revised: 08/03/2022] [Accepted: 08/17/2022] [Indexed: 11/17/2022] Open
Abstract
The FDA Animal Rule was devised to facilitate approval of candidate vaccines and therapeutics using animal survival data when human efficacy studies are not practical or ethical. This regulatory pathway is critical for candidates against pathogens with high case fatality rates that prohibit human challenge trials, as well as candidates with low and sporadic incidences of outbreaks that make human field trials difficult. Important components of a vaccine development plan for Animal Rule licensure are the identification of an immune correlate of protection and immunobridging to humans. The relationship of vaccine-induced immune responses to survival after vaccination and challenge must be established in validated animal models and then used to infer predictive vaccine efficacy in humans via immunobridging. The Sabin Vaccine Institute is pursuing licensure for candidate filovirus vaccines via the Animal Rule and has convened meetings of key opinion leaders and subject matter experts to define fundamental components for vaccine licensure in the absence of human efficacy data. Here, filoviruses are used as examples to review immune correlates of protection and immunobridging. The points presented herein reflect the presentations and discussions during the second meeting held in October 2021 and are intended to address important considerations for developing immunobridging strategies.
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5
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Finch CL, Martinez C, Leffel E, Skiadopoulos MH, Hacker A, Mwesigwa B, Maïga D, Mugisa I, Munkwase G, Rustomjee R. Vaccine Licensure in the Absence of Human Efficacy Data. Vaccines (Basel) 2022; 10:vaccines10030368. [PMID: 35335000 PMCID: PMC8954083 DOI: 10.3390/vaccines10030368] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Revised: 02/18/2022] [Accepted: 02/19/2022] [Indexed: 02/01/2023] Open
Abstract
Clinical vaccine development and regulatory approval generally occurs in a linear, sequential manner: Phase 1: safety, immunogenicity; Phase 2: immunogenicity, safety, dose ranging, and preliminary efficacy; Phase 3: definitive efficacy, safety, lot consistency; and following regulatory approval, Phase 4: post-marketing safety and effectiveness. For candidate filovirus vaccines, where correlates of protection have not been identified, and phase 2 and 3 efficacy of disease prevention trials untenable, large and/or protracted, each trial may span decades, with full licensure expected only after several decades of development. Given the urgent unmet need for new Marburg virus and Ebola Sudan virus vaccines, the Sabin Vaccine Institute hosted a key stakeholder virtual meeting in May 2021 to explore the possibility of licensure by use of an “animal rule-like” licensure process, based on a risk/benefit assessment specific to regional needs and informed by epidemiology. This may be appropriate for diseases where there are no or limited treatment options, and those prone to sporadic outbreaks with high rates of transmission, morbidity, and mortality. The discussion focused on two contexts: licensure within the Ugandan regulatory environment, a high burden country where Ebola vaccine trials are ongoing, and licensure by the United States FDA—a well-resourced regulatory agency.
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Affiliation(s)
- Courtney L. Finch
- Sabin Vaccine Institute, Washington, DC 20037, USA;
- Correspondence: (C.L.F.); (R.R.)
| | | | | | | | - Adam Hacker
- Coalition for Epidemic Preparedness Innovations, Bloomsbury, London NW1 2BE, UK;
| | - Betty Mwesigwa
- Makerere University Walter Reed Project, Kampala 16524, Uganda;
| | - Diadié Maïga
- Regional Office of Africa, World Health Organization, Brazzaville P.O. Box 06, Congo;
| | - Ian Mugisa
- National Drug Authority, Kampala 23096, Uganda; (I.M.); (G.M.)
| | - Grant Munkwase
- National Drug Authority, Kampala 23096, Uganda; (I.M.); (G.M.)
| | - Roxana Rustomjee
- Sabin Vaccine Institute, Washington, DC 20037, USA;
- Correspondence: (C.L.F.); (R.R.)
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6
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Roozendaal R, Solforosi L, Stieh DJ, Serroyen J, Straetemans R, Dari A, Boulton M, Wegmann F, Rosendahl Huber SK, van der Lubbe JEM, Hendriks J, Le Gars M, Dekking L, Czapska-Casey DN, Guimera N, Janssen S, Tete S, Chandrashekar A, Mercado NB, Yu J, Koudstaal W, Perez-Ruixo JJ, Sadoff J, Barouch DH, Schuitemaker H, Zahn R. SARS-CoV-2 binding and neutralizing antibody levels after Ad26.COV2.S vaccination predict durable protection in rhesus macaques. Nat Commun 2021; 12:5877. [PMID: 34620860 PMCID: PMC8497464 DOI: 10.1038/s41467-021-26117-x] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Accepted: 09/16/2021] [Indexed: 01/08/2023] Open
Abstract
Several COVID-19 vaccines have recently gained authorization for emergency use. Limited knowledge on duration of immunity and efficacy of these vaccines is currently available. Data on other coronaviruses after natural infection suggest that immunity to SARS-CoV-2 might be short-lived, and preliminary evidence indicates waning antibody titers following SARS-CoV-2 infection. In this work, we model the relationship between immunogenicity and protective efficacy of a series of Ad26 vectors encoding stabilized variants of the SARS-CoV-2 Spike protein in rhesus macaques and validate the analyses by challenging macaques 6 months after immunization with the Ad26.COV2.S vaccine candidate that has been selected for clinical development. We show that Ad26.COV2.S confers durable protection against replication of SARS-CoV-2 in the lungs that is predicted by the levels of Spike-binding and neutralizing antibodies, indicating that Ad26.COV2.S could confer durable protection in humans and immunological correlates of protection may enable the prediction of durability of protection.
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Affiliation(s)
| | | | - Daniel J Stieh
- Janssen Vaccines & Prevention B.V., Leiden, The Netherlands
| | - Jan Serroyen
- Janssen Vaccines & Prevention B.V., Leiden, The Netherlands
| | | | | | | | - Frank Wegmann
- Janssen Vaccines & Prevention B.V., Leiden, The Netherlands
| | | | | | - Jenny Hendriks
- Janssen Vaccines & Prevention B.V., Leiden, The Netherlands
| | | | | | | | - Nuria Guimera
- Janssen Vaccines & Prevention B.V., Leiden, The Netherlands
| | - Sarah Janssen
- Janssen Vaccines & Prevention B.V., Leiden, The Netherlands
| | - Sarah Tete
- Janssen Vaccines & Prevention B.V., Leiden, The Netherlands
| | - Abishek Chandrashekar
- Center for Virology and Vaccine Research, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - Noe B Mercado
- Center for Virology and Vaccine Research, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - Jingyou Yu
- Center for Virology and Vaccine Research, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | | | | | - Jerry Sadoff
- Janssen Vaccines & Prevention B.V., Leiden, The Netherlands
| | - Dan H Barouch
- Center for Virology and Vaccine Research, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
- Ragon Institute of MGH, MIT and Harvard, Cambridge, MA, USA
- Harvard Medical School, Boston, MA, USA
- Massachusetts Consortium on Pathogen Readiness, Boston, MA, USA
| | | | - Roland Zahn
- Janssen Vaccines & Prevention B.V., Leiden, The Netherlands.
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Smith K, Garman L, Norris K, Muther J, Duke A, Engler RJM, Nelson MR, Collins LC, Spooner C, Guthridge C, James JA. Insufficient Anthrax Lethal Toxin Neutralization Is Associated with Antibody Subclass and Domain Specificity in the Plasma of Anthrax-Vaccinated Individuals. Microorganisms 2021; 9:microorganisms9061204. [PMID: 34199431 PMCID: PMC8229884 DOI: 10.3390/microorganisms9061204] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Revised: 05/25/2021] [Accepted: 05/28/2021] [Indexed: 11/17/2022] Open
Abstract
Anthrax vaccine adsorbed (AVA) is a significant line of defense against bioterrorist attack from Bacillus anthracis spores. However, in a subset of individuals, this vaccine may produce a suboptimal quantity of anti-protective antigen (PA), antibodies that are poorly neutralizing, and/or antibody titers that wane over time, necessitating annual boosters. To study individuals with such poor responses, we examine the properties of anti-PA in a subset of vaccinated individuals that make significant quantities of antibody but are still unable to neutralize toxin. In this cohort, characterized by poorly neutralizing antibody, we find that increased IgG4 to IgG1 subclass ratios, low antibody avidity, and insufficient antibody targeting domain 4 associate with improper neutralization. Thus, future vaccines and vaccination schedules should be formulated to improve these deficiencies.
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Affiliation(s)
- Kenneth Smith
- Department of Arthritis and Clinical Immunology, Oklahoma Medical Research Foundation, 825 NE 13th St., Oklahoma City, OK 73104, USA; (K.N.); (J.M.); (A.D.); (C.G.)
- Correspondence: (K.S.); (J.A.J.); Tel.: +1-405-271-3275 (K.S.); +1-405-271-4987 (J.A.J.)
| | - Lori Garman
- Department of Genes and Human Disease, Oklahoma Medical Research Foundation, 825 NE 13th St., Oklahoma City, OK 73104, USA;
| | - Kathleen Norris
- Department of Arthritis and Clinical Immunology, Oklahoma Medical Research Foundation, 825 NE 13th St., Oklahoma City, OK 73104, USA; (K.N.); (J.M.); (A.D.); (C.G.)
| | - Jennifer Muther
- Department of Arthritis and Clinical Immunology, Oklahoma Medical Research Foundation, 825 NE 13th St., Oklahoma City, OK 73104, USA; (K.N.); (J.M.); (A.D.); (C.G.)
| | - Angie Duke
- Department of Arthritis and Clinical Immunology, Oklahoma Medical Research Foundation, 825 NE 13th St., Oklahoma City, OK 73104, USA; (K.N.); (J.M.); (A.D.); (C.G.)
| | - Renata J. M. Engler
- Walter Reed National Military Medical Center, 8901 Wisconsin Ave, Bethesda, MD 20814, USA; (R.J.M.E.); (M.R.N.); (L.C.C.); (C.S.)
| | - Michael R. Nelson
- Walter Reed National Military Medical Center, 8901 Wisconsin Ave, Bethesda, MD 20814, USA; (R.J.M.E.); (M.R.N.); (L.C.C.); (C.S.)
| | - Limone C. Collins
- Walter Reed National Military Medical Center, 8901 Wisconsin Ave, Bethesda, MD 20814, USA; (R.J.M.E.); (M.R.N.); (L.C.C.); (C.S.)
| | - Christina Spooner
- Walter Reed National Military Medical Center, 8901 Wisconsin Ave, Bethesda, MD 20814, USA; (R.J.M.E.); (M.R.N.); (L.C.C.); (C.S.)
| | - Carla Guthridge
- Department of Arthritis and Clinical Immunology, Oklahoma Medical Research Foundation, 825 NE 13th St., Oklahoma City, OK 73104, USA; (K.N.); (J.M.); (A.D.); (C.G.)
| | - Judith A. James
- Department of Arthritis and Clinical Immunology, Oklahoma Medical Research Foundation, 825 NE 13th St., Oklahoma City, OK 73104, USA; (K.N.); (J.M.); (A.D.); (C.G.)
- Department of Microbiology and Immunology, Oklahoma University Health Science Center, 940 Stanton L. Young Blvd, Oklahoma City, OK 73104, USA
- Departments of Medicine and Pathology, Oklahoma University Health Science Center, 1000 Stanton L. Young Blvd, Oklahoma City, OK 73104, USA
- Correspondence: (K.S.); (J.A.J.); Tel.: +1-405-271-3275 (K.S.); +1-405-271-4987 (J.A.J.)
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8
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Kelly SM, Larsen KR, Darling R, Petersen AC, Bellaire BH, Wannemuehler MJ, Narasimhan B. Single-dose combination nanovaccine induces both rapid and durable humoral immunity and toxin neutralizing antibody responses against Bacillus anthracis. Vaccine 2021; 39:3862-3870. [PMID: 34090702 DOI: 10.1016/j.vaccine.2021.05.077] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Revised: 04/24/2021] [Accepted: 05/23/2021] [Indexed: 12/11/2022]
Abstract
Bacillus anthracis, the causative agent of anthrax, continues to be a prominent biological warfare and bioterrorism threat. Vaccination is likely to remain the most effective and user-friendly public health measure to counter this threat in the foreseeable future. The commercially available AVA BioThrax vaccine has a number of shortcomings where improvement would lead to a more practical and effective vaccine for use in the case of an exposure event. Identification of more effective adjuvants and novel delivery platforms is necessary to improve not only the effectiveness of the anthrax vaccine, but also enhance its shelf stability and ease-of-use. Polyanhydride particles have proven to be an effective platform at adjuvanting the vaccine-associated adaptive immune response as well as enhancing stability of encapsulated antigens. Another class of adjuvants, the STING pathway-targeting cyclic dinucleotides, have proven to be uniquely effective at inducing a beneficial inflammatory response that leads to the rapid induction of high titer antibodies post-vaccination capable of providing protection against bacterial pathogens. In this work, we evaluate the individual contributions of cyclic di-GMP (CDG), polyanhydride nanoparticles, and a combination thereof towards inducing neutralizing antibody (nAb) against the secreted protective antigen (PA) from B. anthracis. Our results show that the combination nanovaccine elicited rapid, high titer, and neutralizing IgG anti-PA antibody following single dose immunization that persisted for at least 108 DPI.
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Affiliation(s)
- Sean M Kelly
- Department of Chemical and Biological Engineering, Iowa State University, Ames, IA, United States; Nanovaccine Institute, Ames, IA, United States
| | - Kristina R Larsen
- Department of Veterinary Microbiology and Preventive Medicine, Iowa State University, Ames, IA, United States; Interdepartmental Microbiology Program, Iowa State University, Ames, IA, United States
| | - Ross Darling
- Department of Veterinary Microbiology and Preventive Medicine, Iowa State University, Ames, IA, United States
| | - Andrew C Petersen
- Department of Veterinary Microbiology and Preventive Medicine, Iowa State University, Ames, IA, United States
| | - Bryan H Bellaire
- Department of Veterinary Microbiology and Preventive Medicine, Iowa State University, Ames, IA, United States; Interdepartmental Microbiology Program, Iowa State University, Ames, IA, United States; Nanovaccine Institute, Ames, IA, United States
| | - Michael J Wannemuehler
- Department of Veterinary Microbiology and Preventive Medicine, Iowa State University, Ames, IA, United States; Nanovaccine Institute, Ames, IA, United States.
| | - Balaji Narasimhan
- Department of Chemical and Biological Engineering, Iowa State University, Ames, IA, United States; Nanovaccine Institute, Ames, IA, United States.
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9
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Nonhuman primate to human immunobridging to infer the protective effect of an Ebola virus vaccine candidate. NPJ Vaccines 2020; 5:112. [PMID: 33335092 PMCID: PMC7747701 DOI: 10.1038/s41541-020-00261-9] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Accepted: 11/13/2020] [Indexed: 01/07/2023] Open
Abstract
It has been proven challenging to conduct traditional efficacy trials for Ebola virus (EBOV) vaccines. In the absence of efficacy data, immunobridging is an approach to infer the likelihood of a vaccine protective effect, by translating vaccine immunogenicity in humans to a protective effect, using the relationship between vaccine immunogenicity and the desired outcome in a suitable animal model. We here propose to infer the protective effect of the Ad26.ZEBOV, MVA-BN-Filo vaccine regimen with an 8-week interval in humans by immunobridging. Immunogenicity and protective efficacy data were obtained for Ad26.ZEBOV and MVA-BN-Filo vaccine regimens using a fully lethal EBOV Kikwit challenge model in cynomolgus monkeys (nonhuman primates [NHP]). The association between EBOV neutralizing antibodies, glycoprotein (GP)-binding antibodies, and GP-reactive T cells and survival in NHP was assessed by logistic regression analysis. Binding antibodies against the EBOV surface GP were identified as the immune parameter with the strongest correlation to survival post EBOV challenge, and used to infer the predicted protective effect of the vaccine in humans using published data from phase I studies. The human vaccine-elicited EBOV GP-binding antibody levels are in a range associated with significant protection against mortality in NHP. Based on this immunobridging analysis, the EBOV GP-specific-binding antibody levels elicited by the Ad26.ZEBOV, MVA-BN-Filo vaccine regimen in humans will likely provide protection against EBOV disease.
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10
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Shearer JD, Henning L, Sanford DC, Li N, Skiadopoulos MH, Reece JJ, Ionin B, Savransky V. Efficacy of the AV7909 anthrax vaccine candidate in guinea pigs and nonhuman primates following two immunizations two weeks apart. Vaccine 2020; 39:1-5. [PMID: 33199078 DOI: 10.1016/j.vaccine.2020.10.095] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Revised: 10/17/2020] [Accepted: 10/30/2020] [Indexed: 11/28/2022]
Abstract
The anthrax vaccine candidate AV7909 is being developed as a next-generation vaccine for post-exposure prophylaxis (PEP) against inhalational anthrax. In clinical studies, two vaccinations with AV7909 administered either two or four weeks apart induced an enhanced immune response compared to BioThrax® (Anthrax Vaccine Adsorbed) (AVA). Anthrax toxin-neutralizing antibody (TNA) levels on Day 70 following initial vaccination that were associated with protection of animals exposed to inhalational anthrax were previously reported for the 0, 4-week AV7909 vaccination regimen. The current study shows that a 0, 2-week AV7909 vaccination regimen protected guinea pigs (GPs) and nonhuman primates (NHPs) against a lethal inhalational anthrax challenge on Days 28 and 70 after the first immunization. An earlier induction of protective TNA levels using a 0, 2-week AV7909 vaccination regimen may provide benefit over the currently approved AVA PEP 0, 2, and 4-week vaccination regimen.
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Affiliation(s)
- Jeffry D Shearer
- Emergent BioSolutions Inc., 300 Professional Drive, Gaithersburg, MD 20879, USA
| | - Lisa Henning
- Battelle Biomedical Research Center, Columbus, OH 43201, USA
| | | | - Na Li
- Emergent BioSolutions Inc., 300 Professional Drive, Gaithersburg, MD 20879, USA
| | | | - Joshua J Reece
- Emergent BioSolutions Inc., 300 Professional Drive, Gaithersburg, MD 20879, USA
| | - Boris Ionin
- Emergent BioSolutions Inc., 300 Professional Drive, Gaithersburg, MD 20879, USA
| | - Vladimir Savransky
- Emergent BioSolutions Inc., 300 Professional Drive, Gaithersburg, MD 20879, USA.
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11
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Bahadoran Z, Mirmiran P, Kashfi K, Ghasemi A. Importance of Systematic Reviews and Meta-analyses of Animal Studies: Challenges for Animal-to-Human Translation. JOURNAL OF THE AMERICAN ASSOCIATION FOR LABORATORY ANIMAL SCIENCE : JAALAS 2020; 59:469-477. [PMID: 32727637 PMCID: PMC7479780 DOI: 10.30802/aalas-jaalas-19-000139] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Results of animal experiments are used for understanding the pathophysiology of diseases, assessing safety and efficacy of newly developed drugs, and monitoring environmental health hazards among others. Systematic reviews and meta-analyses of animal data are important tools to condense animal evidence and translate the data into practical clinical applications. Such studies are conducted to explore heterogeneity, to generate new hypotheses about pathophysiology and treatment, to design new clinical trial modalities, and to test the efficacy and the safety of the various interventions. Here, we provide an overview regarding the importance of systematic reviews and meta-analyses of animal data and discuss common challenges and their potential solutions. Current evidence highlights various problems and challenges that surround these issues, including lack of generalizability of data obtained from animal models, failure in translating data obtained from animals to humans, poor experimental design and the reporting of the animal studies, heterogeneity of the data collected, and methodologic weaknesses of animal systematic reviews and meta-analyses. Systematic reviews and meta-analyses of animal studies can catalyze translational processes more effectively if they focus on a well-defined hypothesis along with addressing clear inclusion and exclusion criteria, publication bias, heterogeneity of the data, and a coherent and well-balanced assessment of studies' quality.
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Affiliation(s)
- Zahra Bahadoran
- Nutrition and Endocrine Research Center, Research Institute for Endocrine Sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Parvin Mirmiran
- Department of Clinical Nutrition and Human Dietetics, Faculty of Nutrition Sciences and Food Technology, National Nutrition and Food Technology Research Institute, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Khosrow Kashfi
- Department of Molecular, Cellular and Biomedical Sciences, Sophie Davis School of Biomedical Education, City University of New York School of Medicine, New York, New York
| | - Asghar Ghasemi
- Endocrine Physiology Research Center, Research Institute for Endocrine Sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran,Corresponding author.
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12
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Savransky V, Ionin B, Reece J. Current Status and Trends in Prophylaxis and Management of Anthrax Disease. Pathogens 2020; 9:E370. [PMID: 32408493 PMCID: PMC7281134 DOI: 10.3390/pathogens9050370] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Revised: 04/29/2020] [Accepted: 05/07/2020] [Indexed: 12/30/2022] Open
Abstract
Bacillus anthracis has been identified as a potential military and bioterror agent as it is relatively simple to produce, with spores that are highly resilient to degradation in the environment and easily dispersed. These characteristics are important in describing how anthrax could be used as a weapon, but they are also important in understanding and determining appropriate prevention and treatment of anthrax disease. Today, anthrax disease is primarily enzootic and found mostly in the developing world, where it is still associated with considerable mortality and morbidity in humans and livestock. This review article describes the spectrum of disease caused by anthrax and the various prevention and treatment options. Specifically we discuss the following; (1) clinical manifestations of anthrax disease (cutaneous, gastrointestinal, inhalational and intravenous-associated); (2) immunology of the disease; (3) an overview of animal models used in research; (4) the current World Health Organization and U.S. Government guidelines for investigation, management, and prophylaxis; (5) unique regulatory approaches to licensure and approval of anthrax medical countermeasures; (6) the history of vaccination and pre-exposure prophylaxis; (7) post-exposure prophylaxis and disease management; (8) treatment of symptomatic disease through the use of antibiotics and hyperimmune or monoclonal antibody-based antitoxin therapies; and (9) the current landscape of next-generation product candidates under development.
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Affiliation(s)
- Vladimir Savransky
- Emergent BioSolutions Inc., 300 Professional Drive, Gaithersburg, MD 20879, USA; (B.I.); (J.R.)
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Clark A, Wolfe DN. Current State of Anthrax Vaccines and Key R&D Gaps Moving Forward. Microorganisms 2020; 8:microorganisms8050651. [PMID: 32365729 PMCID: PMC7285291 DOI: 10.3390/microorganisms8050651] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Revised: 04/25/2020] [Accepted: 04/27/2020] [Indexed: 11/16/2022] Open
Abstract
A licensed anthrax vaccine has been available for pre-exposure prophylaxis in the United States since 1970, and it was approved for use as a post-exposure prophylaxis, in combination with antibiotic treatment, in 2015. A variety of other vaccines are available in other nations, approved under various regulatory frameworks. However, investments in anthrax vaccines continue due to the severity of the threat posed by this bacterium, as both a naturally occurring pathogen and the potential for use as a bioweapon. In this review, we will capture the current landscape of anthrax vaccine development, focusing on those lead candidates in clinical development. Although approved products are available, a robust pipeline of candidate vaccines are still in development to try to address some of the key research gaps in the anthrax vaccine field. We will then highlight some of the most pressing needs in terms of anthrax vaccine research.
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Abstract
The Bacillus cereus group includes several Bacillus species with closely related phylogeny. The most well-studied members of the group, B. anthracis, B. cereus, and B. thuringiensis, are known for their pathogenic potential. Here, we present the historical rationale for speciation and discuss shared and unique features of these bacteria. Aspects of cell morphology and physiology, and genome sequence similarity and gene synteny support close evolutionary relationships for these three species. For many strains, distinct differences in virulence factor synthesis provide facile means for species assignment. B. anthracis is the causative agent of anthrax. Some B. cereus strains are commonly recognized as food poisoning agents, but strains can also cause localized wound and eye infections as well as systemic disease. Certain B. thuringiensis strains are entomopathogens and have been commercialized for use as biopesticides, while some strains have been reported to cause infection in immunocompromised individuals. In this article we compare and contrast B. anthracis, B. cereus, and B. thuringiensis, including ecology, cell structure and development, virulence attributes, gene regulation and genetic exchange systems, and experimental models of disease.
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Bower WA, Schiffer J, Atmar RL, Keitel WA, Friedlander AM, Liu L, Yu Y, Stephens DS, Quinn CP, Hendricks K. Use of Anthrax Vaccine in the United States: Recommendations of the Advisory Committee on Immunization Practices, 2019. MMWR Recomm Rep 2019; 68:1-14. [PMID: 31834290 PMCID: PMC6918956 DOI: 10.15585/mmwr.rr6804a1] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
This report updates the 2009 recommendations from the CDC Advisory Committee on Immunization Practices (ACIP) regarding use of anthrax vaccine in the United States (Wright JG, Quinn CP, Shadomy S, Messonnier N. Use of anthrax vaccine in the United States: recommendations of the Advisory Committee on Immunization Practices [ACIP)], 2009. MMWR Recomm Rep 2010;59[No. RR-6]). The report 1) summarizes data on estimated efficacy in humans using a correlates of protection model and safety data published since the last ACIP review, 2) provides updated guidance for use of anthrax vaccine adsorbed (AVA) for preexposure prophylaxis (PrEP) and in conjunction with antimicrobials for postexposure prophylaxis (PEP), 3) provides updated guidance regarding PrEP vaccination of emergency and other responders, 4) summarizes the available data on an investigational anthrax vaccine (AV7909), and 5) discusses the use of anthrax antitoxins for PEP. Changes from previous guidance in this report include the following: 1) a booster dose of AVA for PrEP can be given every 3 years instead of annually to persons not at high risk for exposure to Bacillus anthracis who have previously received the initial AVA 3-dose priming and 2-dose booster series and want to maintain protection; 2) during a large-scale emergency response, AVA for PEP can be administered using an intramuscular route if the subcutaneous route of administration poses significant materiel, personnel, or clinical challenges that might delay or preclude vaccination; 3) recommendations on dose-sparing AVA PEP regimens if the anthrax vaccine supply is insufficient to vaccinate all potentially exposed persons; and 4) clarification on the duration of antimicrobial therapy when used in conjunction with vaccine for PEP. These updated recommendations can be used by health care providers and guide emergency preparedness officials and planners who are developing plans to provide anthrax vaccine, including preparations for a wide-area aerosol release of B. anthracis spores. The recommendations also provide guidance on dose-sparing options, if needed, to extend the supply of vaccine to increase the number of persons receiving PEP in a mass casualty event.
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Kondakova OA, Nikitin NA, Evtushenko EA, Ryabchevskaya EM, Atabekov JG, Karpova OV. Vaccines against anthrax based on recombinant protective antigen: problems and solutions. Expert Rev Vaccines 2019; 18:813-828. [PMID: 31298973 DOI: 10.1080/14760584.2019.1643242] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Introduction: Anthrax is a dangerous bio-terror agent because Bacillus anthracis spores are highly resilient and can be easily aerosolized and disseminated. There is a threat of deliberate use of anthrax spores aerosol that could lead to serious fatal diseases outbreaks. Existing control measures against inhalation form of the disease are limited. All of this has provided an impetus to the development of new generation vaccines. Areas сovered: This review is devoted to challenges and achievements in the design of vaccines based on the anthrax recombinant protective antigen (rPA). Scientific databases have been searched, focusing on causes of PA instability and solutions to this problem, including new approaches of rPA expression, novel rPA-based vaccines formulations as well as the simultaneous usage of PA with other anthrax antigens. Expert opinion: PA is a central anthrax toxin component, playing a key role in the defense against encapsulated and unencapsulated strains. Subunit rPA-based vaccines have a good safety and protective profile. However, there are problems of PA instability that are greatly enhanced when using aluminum adjuvants. New adjuvant compositions, dry formulations and resistant to proteolysis and deamidation mutant PA forms can help to handle this issue. Devising a modern anthrax vaccine requires huge efforts.
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Affiliation(s)
- Olga A Kondakova
- a Department of Virology, Faculty of Biology, Lomonosov Moscow State University , Moscow , Russian Federation
| | - Nikolai A Nikitin
- a Department of Virology, Faculty of Biology, Lomonosov Moscow State University , Moscow , Russian Federation
| | - Ekaterina A Evtushenko
- a Department of Virology, Faculty of Biology, Lomonosov Moscow State University , Moscow , Russian Federation
| | - Ekaterina M Ryabchevskaya
- a Department of Virology, Faculty of Biology, Lomonosov Moscow State University , Moscow , Russian Federation
| | - Joseph G Atabekov
- a Department of Virology, Faculty of Biology, Lomonosov Moscow State University , Moscow , Russian Federation
| | - Olga V Karpova
- a Department of Virology, Faculty of Biology, Lomonosov Moscow State University , Moscow , Russian Federation
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Kang CK, Kim NH, Kim CJ, Rhie GE, Jo SK, Ahn M, Kang J, Choe PG, Park WB, Kim NJ, Oh MD. Immunogenicity and safety of a novel recombinant protective antigen anthrax vaccine (GC1109), a randomized, single-blind, placebo controlled phase II clinical study. Vaccine 2019; 37:3820-3824. [PMID: 31151800 DOI: 10.1016/j.vaccine.2019.05.057] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Revised: 05/16/2019] [Accepted: 05/18/2019] [Indexed: 11/17/2022]
Abstract
BACKGROUND The demand on effective and safe anthrax vaccine is increasing as a part of the preparedness for possible bioterrorism in the future. We performed a randomized, single-blind, placebo controlled phase II clinical study to evaluate the immunogenicity and safety of a novel recombinant protective antigen (rPA) anthrax vaccine, GC1109, in healthy adult volunteers. METHODS Participants were randomized to experiment groups (0.3 mL, 0.5 mL, and 1.0 mL of GC1109) or placebo group (normal saline 0.5 mL) in 2:2:2:1 ratio. They received respective vaccines intramuscularly at 0, 4 and 8 weeks. Immunogenicity was evaluated by seroconversion rate and geometric mean titer (GMT) of lethal toxin neutralizing assay (TNA) and anti-PA IgG by ELISA. Safety was assessed by laboratory tests, and solicited and unsolicited adverse events on diary cards. RESULTS 30, 29, 30 participants were randomized to 0.3, 0.5, and 1.0 mL of GC1109 groups, respectively, while 15 to placebo group. 92 participants received all three doses. In per-protocol analysis, TNA GMTs at week 12 were 296.5, 285.2, and 433.2 in the three groups, respectively. Seroconversion rates measured by ELISA were 100% at week 12 in the three groups. Local and systemic vaccine-related adverse events were frequent; however, most of them were mild, and no serious events were observed. CONCLUSIONS A new rPA anthrax vaccine GC1109 was immunogenic after three doses of intramuscular administration, and was well-tolerated.
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Affiliation(s)
- Chang Kyung Kang
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea; Department of Internal Medicine, Seoul National University Hospital, Seoul, Republic of Korea
| | - Nak-Hyun Kim
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea; Department of Internal Medicine, Seoul National University Hospital, Seoul, Republic of Korea
| | - Chung-Jong Kim
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea; Department of Internal Medicine, Seoul National University Hospital, Seoul, Republic of Korea
| | - Gi-Eun Rhie
- Division of High-risk Pathogens, Center for Laboratory Control of Infectious Diseases, Korea Centers for Disease Control and Prevention, Chungju, Republic of Korea
| | - Su Kyoung Jo
- Division of High-risk Pathogens, Center for Laboratory Control of Infectious Diseases, Korea Centers for Disease Control and Prevention, Chungju, Republic of Korea
| | - Misun Ahn
- GC Pharma Central Research Center, Yongin, Republic of Korea
| | - Jieun Kang
- GC Pharma Central Research Center, Yongin, Republic of Korea
| | - Pyoeng Gyun Choe
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea; Department of Internal Medicine, Seoul National University Hospital, Seoul, Republic of Korea
| | - Wan Beom Park
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea; Department of Internal Medicine, Seoul National University Hospital, Seoul, Republic of Korea
| | - Nam-Joong Kim
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea; Department of Internal Medicine, Seoul National University Hospital, Seoul, Republic of Korea
| | - Myoung-Don Oh
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea; Department of Internal Medicine, Seoul National University Hospital, Seoul, Republic of Korea.
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Weir GM, MacDonald LD, Rajagopalan R, Sivko GS, Valderas MW, Rayner J, Berger BJ, Sammatur L, Stanford MM. Single dose of DPX-rPA, an enhanced-delivery anthrax vaccine formulation, protects against a lethal Bacillus anthracis spore inhalation challenge. NPJ Vaccines 2019; 4:6. [PMID: 30774997 PMCID: PMC6368554 DOI: 10.1038/s41541-019-0102-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2018] [Accepted: 01/16/2019] [Indexed: 01/15/2023] Open
Abstract
Anthrax is a serious biological threat caused by pulmonary exposure to aerosolized spores of Bacillus anthracis. Biothrax® (anthrax vaccine adsorbed (AVA)) is the only Food and Drug Administration-licensed vaccine and requires five administrations over 12 months with annual boosting to maintain pre-exposure prophylaxis. Here we report the evaluation of a single intramuscular injection of recombinant B. anthracis-protective antigen (rPA) formulated in the DPX delivery platform. Immune responses were compared to an alum-based formulation in mice and rabbits. Serological analysis of anti-rPA immunoglobulin G and toxin neutralization activity demonstrated higher responses induced by DPX-rPA when compared to rPA in alum. DPX-rPA was compared to AVA in rabbits and non-human primates (NHPs). In both species, DPX-rPA generated responses after a single immunization, whereas AVA required two immunizations. In rabbits, single injection of DPX-rPA or two injections of AVA conferred 100% protection from anthrax challenge. In NHPs, single-dose DPX-rPA was 100% protective against challenge, whereas one animal in the two-dose AVA group and all saline administered animals succumbed to infection. DPX-rPA was minimally reactogenic in all species tested. These data indicate that DPX-rPA may offer improvement over AVA by reducing the doses needed for protective immune responses and is a promising candidate as a new-generation anthrax vaccine. A lipid-based anthrax vaccine formulation offers immunity from the first injection. Bacillus anthracis is a lethal pathogen at high risk for use in biological warfare. The only FDA-licensed vaccine for anthrax, AVA, requires multiple doses over six months followed by regular boosters, indicating a need for rapidly immunizing vaccines. Genevieve Weir and Lisa MacDonald, from IMV Inc., with Canadian and US collaborators, here describe a prophylactic consisting of B. anthracis antigens suspended in a lipid-in-oil formulation. Their candidate, DPX-rPA, generated antigen-specific antibodies in rabbits and monkeys after one dose, compared to two for AVA. DPX-rPA also protected both species from B. anthracis spores after one dose. The results indicate that single-dose DPX-rPA is equally protective as two doses of AVA and could serve as pre-exposure and post-exposure prophylaxis. Future studies may confirm its potential as a vaccine for humans.
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Affiliation(s)
- Genevieve M Weir
- IMV Inc., 130 Eileen Stubbs Avenue, Suite 19, Dartmouth, NS B3B 2C4 Canada
| | - Lisa D MacDonald
- IMV Inc., 130 Eileen Stubbs Avenue, Suite 19, Dartmouth, NS B3B 2C4 Canada
| | | | - Gloria S Sivko
- 2Battelle, 1425 Plain City Georgesville Road, West Jefferson, OH 43162 USA
| | | | - Jonathan Rayner
- 3Southern Research, 2000 9th Avenue S, Birmingham, AL 35205 USA
| | - Bradley J Berger
- 4Suffield Research Centre, Defence Research and Development Canada, Medicine Hat, AB T1A 8K6 Canada
| | - Leeladhar Sammatur
- IMV Inc., 130 Eileen Stubbs Avenue, Suite 19, Dartmouth, NS B3B 2C4 Canada
| | - Marianne M Stanford
- IMV Inc., 130 Eileen Stubbs Avenue, Suite 19, Dartmouth, NS B3B 2C4 Canada.,5Department of Microbiology and Immunology, Dalhousie University, 5850 College Street, Room 7-C, PO BOX 15000, Halifax, NS B3H 4R2 Canada
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19
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Single vector platform vaccine protects against lethal respiratory challenge with Tier 1 select agents of anthrax, plague, and tularemia. Sci Rep 2018; 8:7009. [PMID: 29725025 PMCID: PMC5934503 DOI: 10.1038/s41598-018-24581-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2018] [Accepted: 04/04/2018] [Indexed: 01/26/2023] Open
Abstract
Bacillus anthracis, Yersinia pestis, and Francisella tularensis are the causative agents of Tier 1 Select Agents anthrax, plague, and tularemia, respectively. Currently, there are no licensed vaccines against plague and tularemia and the licensed anthrax vaccine is suboptimal. Here we report F. tularensis LVS ΔcapB (Live Vaccine Strain with a deletion in capB)- and attenuated multi-deletional Listeria monocytogenes (Lm)-vectored vaccines against all three aforementioned pathogens. We show that LVS ΔcapB- and Lm-vectored vaccines express recombinant B. anthracis, Y. pestis, and F. tularensis immunoprotective antigens in broth and in macrophage-like cells and are non-toxic in mice. Homologous priming-boosting with the LVS ΔcapB-vectored vaccines induces potent antigen-specific humoral and T-cell-mediated immune responses and potent protective immunity against lethal respiratory challenge with all three pathogens. Protection against anthrax was far superior to that obtained with the licensed AVA vaccine and protection against tularemia was comparable to or greater than that obtained with the toxic and unlicensed LVS vaccine. Heterologous priming-boosting with LVS ΔcapB- and Lm-vectored B. anthracis and Y. pestis vaccines also induced potent protective immunity against lethal respiratory challenge with B. anthracis and Y. pestis. The single vaccine platform, especially the LVS ΔcapB-vectored vaccine platform, can be extended readily to other pathogens.
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20
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Henning LN, Carpenter S, Stark GV, Serbina NV. Development of Protective Immunity in New Zealand White Rabbits Challenged with Bacillus anthracis Spores and Treated with Antibiotics and Obiltoxaximab, a Monoclonal Antibody against Protective Antigen. Antimicrob Agents Chemother 2018; 62:e01590-17. [PMID: 29133571 PMCID: PMC5786786 DOI: 10.1128/aac.01590-17] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Accepted: 11/03/2017] [Indexed: 02/08/2023] Open
Abstract
The recommended management of inhalational anthrax, a high-priority bioterrorist threat, includes antibiotics and antitoxins. Obiltoxaximab, a chimeric monoclonal antibody against anthrax protective antigen (PA), is licensed under the U.S. Food and Drug Administration's (FDA's) Animal Rule for the treatment of inhalational anthrax. Because of spore latency, disease reemergence after treatment cessation is a concern, and there is a need to understand the development of endogenous protective immune responses following antitoxin-containing anthrax treatment regimens. Here, acquired protective immunity was examined in New Zealand White (NZW) rabbits challenged with a targeted lethal dose of Bacillus anthracis spores and treated with antibiotics, obiltoxaximab, or a combination of both. Survivors of the primary challenge were rechallenged 9 months later and monitored for survival. Survival rates after primary and rechallenge for controls and animals treated with obiltoxaximab, levofloxacin, or a combination of both were 0, 65, 100, and 95%, and 0, 100, 95, and 89%, respectively. All surviving immune animals had circulating antibodies to PA and serum toxin-neutralizing titers prior to rechallenge. Following rechallenge, systemic bacteremia and toxemia were not detected in most animals, and the levels of circulating anti-PA IgG titers increased starting at 5 days postrechallenge. We conclude that treatment with obiltoxaximab, alone or combined with antibiotics, significantly improves the survival of rabbits that received a lethal inhalation B. anthracis spore challenge dose and does not interfere with the development of immunity. Survivors of primary challenge are protected against reexposure, have rare incidents of systemic bacteremia and toxemia, and have evidence of an anamnestic response.
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Correlation between anthrax lethal toxin neutralizing antibody levels and survival in guinea pigs and nonhuman primates vaccinated with the AV7909 anthrax vaccine candidate. Vaccine 2017; 35:4952-4959. [PMID: 28774566 DOI: 10.1016/j.vaccine.2017.07.076] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2017] [Revised: 06/22/2017] [Accepted: 07/23/2017] [Indexed: 01/29/2023]
Abstract
The anthrax vaccine candidate AV7909 is being developed as a next generation vaccine for a post-exposure prophylaxis (PEP) indication against anthrax. AV7909 consists of the Anthrax Vaccine Adsorbed (AVA, BioThrax®) bulk drug substance adjuvanted with the immunostimulatory oligodeoxynucleotide (ODN) compound, CPG 7909. The addition of CPG 7909 to AVA enhances both the magnitude and the kinetics of antibody responses in animals and human subjects, making AV7909 a suitable next-generation vaccine for use in a PEP setting. The studies described here provide initial information on AV7909-induced toxin-neutralizing antibody (TNA) levels associated with the protection of animals from lethal Bacillus anthracis challenge. Guinea pigs or nonhuman primates (NHPs) were immunized on Days 0 and 28 with various dilutions of AV7909, AVA or a saline or Alhydrogel+CPG 7909 control. Animals were challenged via the inhalational route with a lethal dose of aerosolized B. anthracis (Ames strain) spores and observed for clinical signs of disease and mortality. The relationship between pre-challenge serum TNA levels and survival following challenge was determined in order to calculate a threshold TNA level associated with protection. Immunisation with AV7909 induced a rapid, highly protective TNA response in guinea pigs and NHPs. Surprisingly, the TNA threshold associated with a 70% probability of survival for AV7909 immunized animals was substantially lower than the threshold which has been established for the licensed AVA vaccine. The results of this study suggest that the TNA threshold of protection against anthrax could be modified by the addition of an immune stimulant such as CPG 7909 and that the TNA levels associated with protection may be vaccine-specific.
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Protection against inhalation anthrax by immunization with Salmonella enterica serovar Typhi Ty21a stably producing protective antigen of Bacillus anthracis. NPJ Vaccines 2017; 2:17. [PMID: 29263873 PMCID: PMC5627300 DOI: 10.1038/s41541-017-0018-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2016] [Revised: 04/28/2017] [Accepted: 05/11/2017] [Indexed: 02/08/2023] Open
Abstract
The national blueprint for biodefense concluded that the United States is underprepared for biological threats. The licensed anthrax vaccine absorbed vaccine, BioThrax, requires administration of at least 3–5 intramuscular doses. The anthrax vaccine absorbed vaccine consists of complex cell-free culture filtrates of a toxigenic Bacillus anthracis strain and causes tenderness at the injection site and significant adverse events. We integrated a codon-optimized, protective antigen gene of B. anthracis (plus extracellular secretion machinery), into the chromosome of the licensed, oral, live-attenuated typhoid fever vaccineTy21a to form Ty21a-PA-01 and demonstrated excellent expression of the gene encoding protective antigen. We produced the vaccine in a 10-L fermenter; foam-dried and vialed it, and characterized the dried product. The vaccine retained ~50% viability for 20 months at ambient temperature. Sera from animals immunized by the intraperitoneal route had high levels of anti-protective antigen antibodies by enzyme-linked immunosorbent assay and anthrax lethal toxin-neutralizing activity. Immunized mice were fully protected against intranasal challenge with ~5 LD50 of B. anthracis Sterne spores, and 70% (7/10) of vaccinated rabbits were protected against aerosol challenge with 200 LD50 of B. anthracis Ames spores. There was a significant correlation between protection and antibody levels determined by enzyme-linked immunosorbent assay and toxin-neutralizing activity. These data provide the foundation for achievement of our ultimate goal, which is to develop an oral anthrax vaccine that is stable at ambient temperatures and induces the rapid onset of durable, high-level protection after a 1-week immunization regimen. A vaccine candidate for anthrax infection shows promise for improving preparedness for a biological attack. Bacillus anthracis, the bacterium responsible for anthrax is a top-tier bioterrorism agent due to its high lethality and spore stability. The current FDA-approved anthrax vaccine and other vaccine candidates in development lack ease of preparation, have short shelf lives and adverse effects. B. Kim Lee Sim of Protein Potential LLC and her collaborators combined key B. anthracis genetic material into an existing typhoid vaccine. The vaccine vector possesses high stability, a strong safety record, and offers long-term protection after oral administration, which Sim’s group hopes to preserve in their candidate anthrax vaccine. The team showed that their hybrid vaccine conferred excellent protection in rabbits and a short vaccination regimen, and suggest further studies into its suitability for human vaccine studies.
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Zeiss CJ, Allore HG, Beck AP. Established patterns of animal study design undermine translation of disease-modifying therapies for Parkinson's disease. PLoS One 2017; 12:e0171790. [PMID: 28182759 PMCID: PMC5300282 DOI: 10.1371/journal.pone.0171790] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Accepted: 01/25/2017] [Indexed: 11/18/2022] Open
Abstract
Translation of disease-modifying therapies in neurodegenerative disease has been disappointing. Parkinson's disease (PD) was used to compare patterns of preclinical study design for symptomatic and potentially disease-modifying interventions. We examined the relationship of model, intervention type and timing, outcomes and outcome measures in 543 animal and human studies (1973-2015) across a contemporary cohort of animal and human interventional studies (n = 445), animal studies for approved interventions (n = 28), animal and human studies for those that failed to translate (n = 70). Detailed study design data were collected for 216 studies in non-human primate (NHP) and rodent toxin-induced models. Species-specific patterns of study design prevailed regardless of whether interventions were symptomatic or potentially disease-modifying. In humans and NHPs, interventions were typically given to both sexes well after the PD phenotype was established, and clinical outcome measures were collected at single (symptomatic) or multiple (disease-modifying) time-points. In rodents, interventions often preceded induction of the model, acute toxic protocols were common, usually given to young males, clinical outcome measures were used less commonly, and outcomes were less commonly assessed at multiple time points. These patterns were more prevalent in mice than rats. In contrast, study design factors such as randomization and blinding did not differ appreciably across symptomatic and disease-modifying intervention categories. The translational gap for potentially disease-modifying interventions in PD in part results from study designs, particularly in mice, that fail to model the progressive nature and relatively late intervention characteristic of PD, or that anchor mechanistic and neuropathologic data to longitudinal clinical outcomes. Even if measures to improve reproducibility are broadly adopted, perpetuation of these norms will continue to impede effective translation.
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Affiliation(s)
- Caroline J. Zeiss
- Section of Comparative Medicine, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Heather G. Allore
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, United States of America
- Department of Biostatistics, Yale School of Public Health, New Haven, Connecticut, United States of America
| | - Amanda P. Beck
- Department of Pathology, Albert Einstein College of Medicine, Bronx, New York, United States of America
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Cross-species prediction of human survival probabilities for accelerated anthrax vaccine absorbed (AVA) regimens and the potential for vaccine and antibiotic dose sparing. Vaccine 2016; 34:6512-6517. [PMID: 27558619 DOI: 10.1016/j.vaccine.2016.06.041] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Revised: 04/09/2016] [Accepted: 06/06/2016] [Indexed: 11/23/2022]
Abstract
Anthrax vaccine adsorbed (AVA, BioThrax) was recently approved by the Food and Drug Administration (FDA) for a post-exposure prophylaxis (PEP) indication in adults 18-65years of age. The schedule is three doses administered subcutaneous (SC) at 2-week intervals (0, 2, and 4weeks), in conjunction with a 60-day course of antimicrobials. The Public Health Emergency Medical Countermeasures Enterprise (PHEMCE) developed an animal model to support assessment of a shortened antimicrobial PEP duration following Bacillus anthracis exposure. A nonhuman primate (NHP) study was completed to evaluate the efficacy of a two dose anthrax vaccine absorbed (AVA) schedule (0, 2weeks) aerosol challenged with high levels of B. anthracis spores at week4- the time point at which humans would receive the third vaccination of the approved PEP schedule. Here we use logistic regression models to combine the survival data from the NHP study along with serum anthrax lethal toxin neutralizing activity (TNA) and anti-PA IgG measured by enzyme linked immunosorbent assay (ELISA) data to perform a cross-species analysis to estimate survival probabilities in vaccinated human populations at this time interval (week4 of the PEP schedule). The bridging analysis demonstrated that high levels of NHP protection also yield high predicted probability of human survival just 2weeks after the second dose of vaccine with the full or half antigen dose regimen. The absolute difference in probability of human survival between the full and half antigen dose was estimated to be at most approximately 20%, indicating that more investigation of the half-antigen dose for vaccine dose sparing strategies may be warranted.
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Milley B, Kiwan R, Ott GS, Calacsan C, Kachura M, Campbell JD, Kanzler H, Coffman RL. Optimization, Production, and Characterization of a CpG-Oligonucleotide-Ficoll Conjugate Nanoparticle Adjuvant for Enhanced Immunogenicity of Anthrax Protective Antigen. Bioconjug Chem 2016; 27:1293-304. [PMID: 27074387 PMCID: PMC4873889 DOI: 10.1021/acs.bioconjchem.6b00107] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
![]()
We have synthesized and characterized
a novel phosphorothioate
CpG oligodeoxynucleotide (CpG ODN)-Ficoll conjugated nanoparticulate
adjuvant, termed DV230-Ficoll. This adjuvant was constructed from
an amine-functionalized-Ficoll, a heterobifunctional linker (succinimidyl-[(N-maleimidopropionamido)-hexaethylene glycol] ester) and
the CpG-ODN DV230. Herein, we describe the evaluation of the purity
and reactivity of linkers of different lengths for CpG-ODN-Ficoll
conjugation, optimization of linker coupling, and conjugation of thiol-functionalized
CpG to maleimide-functionalized Ficoll and process scale-up. Physicochemical
characterization of independently produced lots of DV230-Ficoll reveal
a bioconjugate with a particle size of approximately 50 nm and covalent
attachment of more than 100 molecules of CpG per Ficoll. Solutions
of purified DV230-Ficoll were stable for at least 12 months at frozen
and refrigerated temperatures and stability was further enhanced in
lyophilized form. Compared to nonconjugated monomeric DV230, the DV230-Ficoll
conjugate demonstrated improved in vitro potency for induction of
IFN-α from human peripheral blood mononuclear cells and induced
higher titer neutralizing antibody responses against coadministered
anthrax recombinant protective antigen in mice. The processes described
here establish a reproducible and robust process for the synthesis
of a novel, size-controlled, and stable CpG-ODN nanoparticle adjuvant
suitable for manufacture and use in vaccines.
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Affiliation(s)
- Bob Milley
- Dynavax Technologies Corporation , 2929 Seventh Street, Suite 100, Berkeley, California 94710, United States
| | - Radwan Kiwan
- Dynavax Technologies Corporation , 2929 Seventh Street, Suite 100, Berkeley, California 94710, United States
| | - Gary S Ott
- Dynavax Technologies Corporation , 2929 Seventh Street, Suite 100, Berkeley, California 94710, United States
| | - Carlo Calacsan
- Dynavax Technologies Corporation , 2929 Seventh Street, Suite 100, Berkeley, California 94710, United States
| | - Melissa Kachura
- Dynavax Technologies Corporation , 2929 Seventh Street, Suite 100, Berkeley, California 94710, United States
| | - John D Campbell
- Dynavax Technologies Corporation , 2929 Seventh Street, Suite 100, Berkeley, California 94710, United States
| | - Holger Kanzler
- MedImmune LLC , One MedImmune Way, Gaithersburg, Maryland 20878, United States
| | - Robert L Coffman
- Dynavax Technologies Corporation , 2929 Seventh Street, Suite 100, Berkeley, California 94710, United States
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Mechanistic Analysis of the Effect of Deamidation on the Immunogenicity of Anthrax Protective Antigen. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2016; 23:396-402. [PMID: 26912784 DOI: 10.1128/cvi.00701-15] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Accepted: 02/18/2016] [Indexed: 11/20/2022]
Abstract
The spontaneous modification of proteins, such as deamidation of asparagine residues, can significantly affect the immunogenicity of protein-based vaccines. Using a "genetically deamidated" form of recombinant protective antigen (rPA), we have previously shown that deamidation can decrease the immunogenicity of rPA, the primary component of new-generation anthrax vaccines. In this study, we investigated the biochemical and immunological mechanisms by which deamidation of rPA might decrease the immunogenicity of the protein. We found that loss of the immunogenicity of rPA vaccine was independent of the presence of adjuvant. We assessed the effect of deamidation on the immunodominant neutralizing B-cell epitopes of rPA and found that these epitopes were not significantly affected by deamidation. In order to assess the effect of deamidation on T-cell help for antibody production elicited by rPA vaccine, we examined the ability of the wild-type and genetically deamidated forms of rPA to serve as hapten carriers. We found that when wild-type and genetically deamidated rPA were modified to similar extents with 2,4-dinitrophenyl hapten (DNP) and then used to immunize mice, higher levels of anti-DNP antibodies were elicited by wild-type DNP-rPA than those elicited by the genetically deamidated DNP-rPA, indicating that wild-type rPA elicits more T-cell help than the genetically deamidated form of the protein. These results suggest that a decrease in the ability of deamidated rPA to elicit T-cell help for antibody production is a possible contributor to its lower immunogenicity.
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Evaluation of early immune response-survival relationship in cynomolgus macaques after Anthrax Vaccine Adsorbed vaccination and Bacillus anthracis spore challenge. Vaccine 2016; 34:6518-6528. [PMID: 27155494 DOI: 10.1016/j.vaccine.2016.04.048] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Revised: 04/08/2016] [Accepted: 04/18/2016] [Indexed: 01/02/2023]
Abstract
Anthrax Vaccine Adsorbed (AVA, BioThrax) is approved by the US Food and Drug Administration for post-exposure prophylaxis (PEP) of anthrax in adults. The PEP schedule is 3 subcutaneous (SC) doses (0, 14 and 28 days), in conjunction with a 60 day course of antimicrobials. The objectives of this study were to understand the onset of protection from AVA PEP vaccination and to assess the potential for shortening the duration of antimicrobial treatment (http://www.phe.gov/Preparedness/mcm/phemce/Documents/2014-phemce-sip.pdf). We determined the efficacy against inhalation anthrax in nonhuman primates (NHP) of the first two doses of the PEP schedule by infectious challenge at the time scheduled for receipt of the third PEP dose (Day 28). Forty-eight cynomolgus macaques were randomized to five groups and vaccinated with serial dilutions of AVA on Days 0 and 14. NHP were exposed to Bacillus anthracis Ames spores on Day 28 (target dose 200 LD50 equivalents). Anti-protective antigen (PA) IgG and toxin neutralizing antibody (TNA) responses to vaccination and in post-challenge survivors were determined. Post-challenge blood and selected tissue samples were assessed for B. anthracis at necropsy or end of study (Day 56). Pre-challenge humoral immune responses correlated with survival, which ranged from 24 to 100% survival depending on vaccination group. Surviving, vaccinated animals had elevated anti-PA IgG and TNA levels for the duration of the study, were abacteremic, exhibited no apparent signs of infection, and had no gross or microscopic lesions. However, survivors had residual spores in lung tissues. We conclude that the first two doses of the PEP schedule provide high levels of protection by the scheduled timing of the third dose. These data may also support consideration of a shorter duration PEP antimicrobial regimen.
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28
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Elkins KL, Kurtz SL, De Pascalis R. Progress, challenges, and opportunities in Francisella vaccine development. Expert Rev Vaccines 2016; 15:1183-96. [PMID: 27010448 DOI: 10.1586/14760584.2016.1170601] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Renewed interest in Francisella tularensis has resulted in substantial new information about its pathogenesis and immunology, along with development of useful animal models. While understanding of protective immunity against Francisella remains incomplete, data in both animals and humans suggest that inducing T cell-mediated immunity is crucial for successful vaccination with current candidates such as the Live Vaccine Strain (LVS), with specific antibodies and immune B cells playing supporting roles. Consistent with this idea, recent results indicate that measurements of T cell functions and relative gene expression by immune T cells predict vaccine-induced protection in animal models. Because field trials of new vaccines will be difficult to design, using such measurements to derive potential correlates of protection may be important to bridge between animal efficacy studies and people.
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Affiliation(s)
- Karen L Elkins
- a Division of Bacterial, Parasitic, and Allergenic Products, CBER/FDA , Silver Spring , MD , USA
| | - Sherry L Kurtz
- a Division of Bacterial, Parasitic, and Allergenic Products, CBER/FDA , Silver Spring , MD , USA
| | - Roberto De Pascalis
- a Division of Bacterial, Parasitic, and Allergenic Products, CBER/FDA , Silver Spring , MD , USA
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29
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Humoral and Cell-Mediated Immune Responses to Alternate Booster Schedules of Anthrax Vaccine Adsorbed in Humans. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2016; 23:326-38. [PMID: 26865594 DOI: 10.1128/cvi.00696-15] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2015] [Accepted: 02/02/2016] [Indexed: 12/28/2022]
Abstract
Protective antigen (PA)-specific antibody and cell-mediated immune (CMI) responses to annual and alternate booster schedules of anthrax vaccine adsorbed (AVA; BioThrax) were characterized in humans over 43 months. Study participants received 1 of 6 vaccination schedules: a 3-dose intramuscular (IM) priming series (0, 1, and 6 months) with a single booster at 42 months (4-IM); 3-dose IM priming with boosters at 18 and 42 months (5-IM); 3-dose IM priming with boosters at 12, 18, 30, and 42 months (7-IM); the 1970 licensed priming series of 6 doses (0, 0.5, 1, 6, 12, and 18 months) and two annual boosters (30 and 42 months) administered either subcutaneously (SQ) (8-SQ) or IM (8-IM); or saline placebo control at all eight time points. Antibody response profiles included serum anti-PA IgG levels, subclass distributions, avidity, and lethal toxin neutralization activity (TNA). CMI profiles included frequencies of gamma interferon (IFN-γ)- and interleukin 4 (IL-4)-secreting cells and memory B cells (MBCs), lymphocyte stimulation indices (SI), and induction of IFN-γ, IL-2, IL-4, IL-6, IL-1β, and tumor necrosis factor alpha (TNF-α) mRNA. All active schedules elicited high-avidity PA-specific IgG, TNA, MBCs, and T cell responses with a mixed Th1-Th2 profile and Th2 dominance. Anti-PA IgG and TNA were highly correlated (e.g., month 7,r(2)= 0.86,P< 0.0001, log10 transformed) and declined in the absence of boosters. Boosters administered IM generated the highest antibody responses. Increasing time intervals between boosters generated antibody responses that were faster than and superior to those obtained with the final month 42 vaccination. CMI responses to the 3-dose IM priming remained elevated up to 43 months. (This study has been registered at ClinicalTrials.gov under registration no. NCT00119067.).
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Schiffer JM, McNeil MM, Quinn CP. Recent developments in the understanding and use of anthrax vaccine adsorbed: achieving more with less. Expert Rev Vaccines 2016; 15:1151-62. [PMID: 26942655 DOI: 10.1586/14760584.2016.1162104] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Anthrax Vaccine Adsorbed (AVA, BioThrax™) is the only Food and Drug Administration (FDA) approved vaccine for the prevention of anthrax in humans. Recent improvements in pre-exposure prophylaxis (PrEP) use of AVA include intramuscular (IM) administration and simplification of the priming series to three doses over 6 months. Administration IM markedly reduced the frequency, severity and duration of injection site reactions. Refinement of animal models for inhalation anthrax, identification of immune correlates of protection and cross-species modeling have created opportunities for reductions in the PrEP booster schedule and were pivotal in FDA approval of a post-exposure prophylaxis (PEP) indication. Clinical and nonclinical studies of accelerated PEP schedules and divided doses may provide prospects for shortening the PEP antimicrobial treatment period. These data may assist in determining feasibility of expanded coverage in a large-scale emergency when vaccine demand may exceed availability. Enhancements to the AVA formulation may broaden the vaccine's PEP application.
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Affiliation(s)
- Jarad M Schiffer
- a MPIR Laboratory, Meningitis and Vaccine Preventable Diseases Branch, Division of Bacterial Diseases, National Center for Immunization and Respiratory Diseases , Centers for Disease Control and Prevention (CDC) , Atlanta , GA , USA
| | - Michael M McNeil
- b Immunization Safety Office, Division of Healthcare Quality Promotion , National Center for Emerging and Zoonotic Infectious Diseases , Atlanta , GA , USA
| | - Conrad P Quinn
- c Meningitis and Vaccine Preventable Diseases Branch, Division of Bacterial Diseases , National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention (CDC) , Atlanta , GA , USA
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31
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Kachura MA, Hickle C, Kell SA, Sathe A, Calacsan C, Kiwan R, Hall B, Milley R, Ott G, Coffman RL, Kanzler H, Campbell JD. A CpG-Ficoll Nanoparticle Adjuvant for Anthrax Protective Antigen Enhances Immunogenicity and Provides Single-Immunization Protection against Inhaled Anthrax in Monkeys. THE JOURNAL OF IMMUNOLOGY 2015; 196:284-97. [PMID: 26608924 DOI: 10.4049/jimmunol.1501903] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Accepted: 10/30/2015] [Indexed: 01/07/2023]
Abstract
Nanoparticulate delivery systems for vaccine adjuvants, designed to enhance targeting of secondary lymphoid organs and activation of APCs, have shown substantial promise for enhanced immunopotentiation. We investigated the adjuvant activity of synthetic oligonucleotides containing CpG-rich motifs linked to the sucrose polymer Ficoll, forming soluble 50-nm particles (DV230-Ficoll), each containing >100 molecules of the TLR9 ligand, DV230. DV230-Ficoll was evaluated as an adjuvant for a candidate vaccine for anthrax using recombinant protective Ag (rPA) from Bacillus anthracis. A single immunization with rPA plus DV230-Ficoll induced 10-fold higher titers of toxin-neutralizing Abs in cynomolgus monkeys at 2 wk compared with animals immunized with equivalent amounts of monomeric DV230. Monkeys immunized either once or twice with rPA plus DV230-Ficoll were completely protected from challenge with 200 LD50 aerosolized anthrax spores. In mice, DV230-Ficoll was more potent than DV230 for the induction of innate immune responses at the injection site and draining lymph nodes. DV230-Ficoll was preferentially colocalized with rPA in key APC populations and induced greater maturation marker expression (CD69 and CD86) on these cells and stronger germinal center B and T cell responses, relative to DV230. DV230-Ficoll was also preferentially retained at the injection site and draining lymph nodes and produced fewer systemic inflammatory responses. These findings support the development of DV230-Ficoll as an adjuvant platform, particularly for vaccines such as for anthrax, for which rapid induction of protective immunity and memory with a single injection is very important.
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Affiliation(s)
| | | | | | - Atul Sathe
- Dynavax Technologies, Berkeley, CA 94710; and
| | | | | | - Brian Hall
- Amnis Corp., EMD Millipore, Seattle, WA 98119
| | | | - Gary Ott
- Dynavax Technologies, Berkeley, CA 94710; and
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32
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Williamson ED, Dyson EH. Anthrax prophylaxis: recent advances and future directions. Front Microbiol 2015; 6:1009. [PMID: 26441934 PMCID: PMC4585224 DOI: 10.3389/fmicb.2015.01009] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2015] [Accepted: 09/07/2015] [Indexed: 11/13/2022] Open
Abstract
Anthrax is a serious, potentially fatal disease that can present in four distinct clinical patterns depending on the route of infection (cutaneous, gastrointestinal, pneumonic, or injectional); effective strategies for prophylaxis and therapy are therefore required. This review addresses the complex mechanisms of pathogenesis employed by the bacterium and describes how, as understanding of these has developed over many years, so too have current strategies for vaccination and therapy. It covers the clinical and veterinary use of live attenuated strains of anthrax and the subsequent identification of protein sub-units for incorporation into vaccines, as well as combinations of protein sub-units with spore or other components. It also addresses the application of these vaccines for conventional prophylactic use, as well as post-exposure use in conjunction with antibiotics. It describes the licensed acellular vaccines AVA and AVP and discusses the prospects for a next generation of recombinant sub-unit vaccines for anthrax, balancing the regulatory requirement and current drive for highly defined vaccines, against the risk of losing the “danger” signals required to induce protective immunity in the vaccinee. It considers novel approaches to reduce time to immunity by means of combining, for example, dendritic cell vaccination with conventional approaches and considers current opportunities for the immunotherapy of anthrax.
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Affiliation(s)
| | - Edward Hugh Dyson
- Defence Science and Technology Laboratory Porton Down, Salisbury, UK
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33
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Bridging non-human primate correlates of protection to reassess the Anthrax Vaccine Adsorbed booster schedule in humans. Vaccine 2015; 33:3709-16. [PMID: 26072016 PMCID: PMC6360524 DOI: 10.1016/j.vaccine.2015.05.091] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2015] [Revised: 05/14/2015] [Accepted: 05/29/2015] [Indexed: 11/20/2022]
Abstract
Anthrax Vaccine Adsorbed (AVA, BioThrax) is approved for use in humans as a priming series of 3 intramuscular (i.m.) injections (0, 1, 6 months; 3-IM) with boosters at 12 and 18 months, and annually thereafter for those at continued risk of infection. A reduction in AVA booster frequency would lessen the burden of vaccination, reduce the cumulative frequency of vaccine associated adverse events and potentially expand vaccine coverage by requiring fewer doses per schedule. Because human inhalation anthrax studies are neither feasible nor ethical, AVA efficacy estimates are determined using cross-species bridging of immune correlates of protection (COP) identified in animal models. We have previously reported that the AVA 3-IM priming series provided high levels of protection in non-human primates (NHP) against inhalation anthrax for up to 4 years after the first vaccination. Penalized logistic regressions of those NHP immunological data identified that anti-protective antigen (anti-PA) IgG concentration measured just prior to infectious challenge was the most accurate single COP. In the present analysis, cross-species logistic regression models of this COP were used to predict probability of survival during a 43 month study in humans receiving the current 3-dose priming and 4 boosters (12, 18, 30 and 42 months; 7-IM) and reduced schedules with boosters at months 18 and 42 only (5-IM), or at month 42 only (4-IM). All models predicted high survival probabilities for the reduced schedules from 7 to 43 months. The predicted survival probabilities for the reduced schedules were 86.8% (4-IM) and 95.8% (5-IM) at month 42 when antibody levels were lowest. The data indicated that 4-IM and 5-IM are both viable alternatives to the current AVA pre-exposure prophylaxis schedule.
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34
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Oscherwitz J, Quinn CP, Cease KB. Anthrax vaccine recipients lack antibody against the loop neutralizing determinant: A protective neutralizing epitope from Bacillus anthracis protective antigen. Vaccine 2015; 33:2342-6. [PMID: 25820066 DOI: 10.1016/j.vaccine.2015.03.037] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2014] [Revised: 02/11/2015] [Accepted: 03/12/2015] [Indexed: 11/24/2022]
Abstract
BACKGROUND Epitope-focused immunogens can elicit antibody against the loop neutralizing determinant (LND), a neutralizing epitope found within the 2β2-2β3 loop of protective antigen (PA), which can protect rabbits from high-dose inhalation challenge with Bacillus anthracis Ames strain. Interestingly, data suggests that this epitope is relatively immunosilent in rabbits and non-human primates immunized with full length PA. METHODS To determine whether the LND is immunosilent among humans vaccinated with PA, we screened antisera from AVA- or placebo-vaccinees from a clinical trial for antibody reactive with the LND. RESULTS AVA-vaccinee sera had significant PA-specific antibody compared to placebo-vaccinee sera; however, sera from the two cohorts were indistinguishable with regard to the frequency of individuals with antibody specific for the LND. CONCLUSIONS AVA-vaccinees have a low frequency of antibody reactive with the LND. As with rabbits and non-human primates, the elicitation of LND-specific antibody in humans appears to require immunization with an epitope-focused vaccine.
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Affiliation(s)
- Jon Oscherwitz
- Division of Hematology-Oncology, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI 48105, USA; Veterans Administration Ann Arbor Healthcare System, 2215 Fuller Road, Ann Arbor, MI 48105, USA.
| | - Conrad P Quinn
- Division of Bacterial Diseases, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Kemp B Cease
- Division of Hematology-Oncology, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI 48105, USA; Veterans Administration Ann Arbor Healthcare System, 2215 Fuller Road, Ann Arbor, MI 48105, USA
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35
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Oscherwitz J, Feldman D, Yu F, Cease KB. Epitope-focused peptide immunogens in human use adjuvants protect rabbits from experimental inhalation anthrax. Vaccine 2014; 33:430-6. [PMID: 25454087 DOI: 10.1016/j.vaccine.2014.11.042] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2014] [Revised: 10/28/2014] [Accepted: 11/21/2014] [Indexed: 11/28/2022]
Abstract
BACKGROUND Anthrax represents a formidable bioterrorism threat for which new, optimized vaccines are required. We previously demonstrated that epitope-focused multiple antigenic peptides or a recombinant protein in Freund's adjuvant can elicit Ab against the loop neutralizing determinant (LND), a cryptic linear neutralizing epitope in the 2ß2-2ß3 loop of protective antigen from Bacillus anthracis, which mediated protection of rabbits from inhalation challenge with B. anthracis Ames strain. However, demonstration of efficacy using human-use adjuvants is required before proceeding with further development of an LND vaccine for testing in non-human primates and humans. METHODS To optimize the LND immunogen, we first evaluated the protective efficacy and immune correlates associated with immunization of rabbits with mixtures containing two molecular variants of multiple antigenic peptides in Freunds adjuvant, termed BT-LND(2) and TB-LND(2). TB-LND(2) was then further evaluated for protective efficacy in rabbits employing human-use adjuvants. RESULTS Immunization of rabbits with TB-LND(2) in human-use adjuvants elicited protection from Ames strain spore challenge which was statistically indistinguishable from that elicited through immunization with protective antigen. All TB-LND(2) rabbits with any detectable serum neutralization prior to challenge were protected from aerosolized spore exposure. Remarkably, rabbits immunized with TB-LND(2) in Alhydrogel/CpG had significant anamnestic increases in post-challenge LND-specific Ab and neutralization titers despite little evidence of spore germination in these rabbits. CONCLUSIONS An LND-specific epitope-focused vaccine may complement PA-based vaccines and may represent a complementary stand-alone vaccine for anthrax.
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Affiliation(s)
- Jon Oscherwitz
- Division of Hematology-Oncology, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI 48105, USA; Veterans Administration Ann Arbor Healthcare System, 2215 Fuller Road, Ann Arbor, MI 48105, USA.
| | - Daniel Feldman
- University of Michigan Medical School, Ann Arbor, MI 48105, USA
| | - Fen Yu
- Division of Hematology-Oncology, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI 48105, USA
| | - Kemp B Cease
- Division of Hematology-Oncology, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI 48105, USA; Veterans Administration Ann Arbor Healthcare System, 2215 Fuller Road, Ann Arbor, MI 48105, USA
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36
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Zeiss CJ. Improving the predictive value of interventional animal models data. Drug Discov Today 2014; 20:475-82. [PMID: 25448761 DOI: 10.1016/j.drudis.2014.10.015] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2014] [Revised: 10/03/2014] [Accepted: 10/27/2014] [Indexed: 12/15/2022]
Abstract
For many chronic diseases, translational success using the animal model paradigm has reached an impasse. Using Alzheimer's disease as an example, this review employs a networks-based method to assess repeatability of outcomes across species, by intervention and mechanism. Over 75% of animal studies reported an improved outcome. Strain background was a significant potential confounder. Five percent of interventions had been tested across animals and humans, or examined across three or more animal models. Positive outcomes across species emerged for donepezil, memantine and exercise. Repeatable positive outcomes in animals were identified for the amyloid hypothesis and three additional mechanisms. This approach supports in silico reduction of positive outcomes bias in animal studies.
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Affiliation(s)
- Caroline J Zeiss
- Section of Comparative Medicine, Yale University School of Medicine, 375 Congress Ave, New Haven, CT 06520, USA.
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37
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Lecour S, Bøtker HE, Condorelli G, Davidson SM, Garcia-Dorado D, Engel FB, Ferdinandy P, Heusch G, Madonna R, Ovize M, Ruiz-Meana M, Schulz R, Sluijter JPG, Van Laake LW, Yellon DM, Hausenloy DJ. ESC working group cellular biology of the heart: position paper: improving the preclinical assessment of novel cardioprotective therapies. Cardiovasc Res 2014; 104:399-411. [PMID: 25344369 PMCID: PMC4242141 DOI: 10.1093/cvr/cvu225] [Citation(s) in RCA: 134] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Ischaemic heart disease (IHD) remains the leading cause of death and disability worldwide. As a result, novel therapies are still needed to protect the heart from the detrimental effects of acute ischaemia–reperfusion injury, in order to improve clinical outcomes in IHD patients. In this regard, although a large number of novel cardioprotective therapies discovered in the research laboratory have been investigated in the clinical setting, only a few of these have been demonstrated to improve clinical outcomes. One potential reason for this lack of success may have been the failure to thoroughly assess the cardioprotective efficacy of these novel therapies in suitably designed preclinical experimental animal models. Therefore, the aim of this Position Paper by the European Society of Cardiology Working Group Cellular Biology of the Heart is to provide recommendations for improving the preclinical assessment of novel cardioprotective therapies discovered in the research laboratory, with the aim of increasing the likelihood of success in translating these new treatments into improved clinical outcomes.
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Affiliation(s)
- Sandrine Lecour
- Hatter Institute for Cardiovascular Research in Africa and MRC Inter-University Cape Heart Group, University of Cape Town, Cape Town, South Africa
| | - Hans E Bøtker
- Department of Cardiology, Aarhus University Hospital Skejby, Aarhus N, Denmark
| | - Gianluigi Condorelli
- Humanitas Clinical and Research Institute, National Research Council of Italy, Rozzano, Italy
| | - Sean M Davidson
- The Hatter Cardiovascular Institute, University College London, 67 Chenies Mews
| | - David Garcia-Dorado
- Department of Cardiology, Vall d'Hebron University Hospital and Research Institute, Universitat Autónoma de Barcelona, Barcelona, Spain
| | - Felix B Engel
- Experimental Renal and Cardiovascular Research, Department of Nephropathology, Institute of Pathology, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Peter Ferdinandy
- Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary Pharmahungary Group, Szeged, Hungary
| | - Gerd Heusch
- Institut für Pathophysiologie, West German Heart and Vascular Centre, Universitätsklinikum Essen, Essen, Germany
| | - Rosalinda Madonna
- Institute of Cardiology and Center of Excellence on Aging, 'G. d'Annunzio' University of Chieti, Chieti, Italy Texas Heart Institute, Houston, TX, USA Department of Internal Medicine, University of Texas Medical School, Center of Cardiovascular and Atherosclerosis Research, Houston, TX, USA
| | - Michel Ovize
- Inserm U 1060 (CarMeN_Cardioprotection Team) & CIC de Lyon, Service d'Exploration Fonctionnelles Cardiovasculaires, Hospices Civils de Lyon, Université Claude Bernard Lyon1, Lyon, France
| | - Marisol Ruiz-Meana
- Department of Cardiology, Vall d'Hebron University Hospital and Research Institute, Universitat Autónoma de Barcelona, Barcelona, Spain
| | | | | | - Linda W Van Laake
- University Medical Center Utrecht and Hubrecht Institute, Utrecht, the Netherlands
| | - Derek M Yellon
- The Hatter Cardiovascular Institute, University College London, 67 Chenies Mews
| | - Derek J Hausenloy
- The Hatter Cardiovascular Institute, University College London, 67 Chenies Mews
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38
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Comprehensive analysis and selection of anthrax vaccine adsorbed immune correlates of protection in rhesus macaques. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2014; 21:1512-20. [PMID: 25185577 DOI: 10.1128/cvi.00469-14] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Humoral and cell-mediated immune correlates of protection (COP) for inhalation anthrax in a rhesus macaque (Macaca mulatta) model were determined. The immunological and survival data were from 114 vaccinated and 23 control animals exposed to Bacillus anthracis spores at 12, 30, or 52 months after the first vaccination. The vaccinated animals received a 3-dose intramuscular priming series (3-i.m.) of anthrax vaccine adsorbed (AVA) (BioThrax) at 0, 1, and 6 months. The immune responses were modulated by administering a range of vaccine dilutions. Together with the vaccine dilution dose and interval between the first vaccination and challenge, each of 80 immune response variables to anthrax toxin protective antigen (PA) at every available study time point was analyzed as a potential COP by logistic regression penalized by least absolute shrinkage and selection operator (LASSO) or elastic net. The anti-PA IgG level at the last available time point before challenge (last) and lymphocyte stimulation index (SI) at months 2 and 6 were identified consistently as a COP. Anti-PA IgG levels and lethal toxin neutralization activity (TNA) at months 6 and 7 (peak) and the frequency of gamma interferon (IFN-γ)-secreting cells at month 6 also had statistically significant positive correlations with survival. The ratio of interleukin 4 (IL-4) mRNA to IFN-γ mRNA at month 6 also had a statistically significant negative correlation with survival. TNA had lower accuracy as a COP than did anti-PA IgG response. Following the 3-i.m. priming with AVA, the anti-PA IgG responses at the time of exposure or at month 7 were practicable and accurate metrics for correlating vaccine-induced immunity with protection against inhalation anthrax.
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Hopkins RJ, Howard C, Hunter-Stitt E, Kaptur PE, Pleune B, Muse D, Sheldon E, Davis M, Strout C, Vert-Wong K. Phase 3 trial evaluating the immunogenicity and safety of a three-dose BioThrax® regimen for post-exposure prophylaxis in healthy adults. Vaccine 2014; 32:2217-24. [PMID: 24613523 DOI: 10.1016/j.vaccine.2014.01.073] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2013] [Revised: 01/23/2014] [Accepted: 01/28/2014] [Indexed: 11/27/2022]
Abstract
BACKGROUND This study was conducted to support licensure of a post-exposure prophylaxis indication for BioThrax(®) (anthrax vaccine adsorbed) concurrent with antimicrobials for individuals exposed to aerosolized anthrax spores. METHODS The immunogenicity and safety of a three-dose regimen (0, 2, and 4 weeks) of BioThrax administered subcutaneously (SC) were evaluated in 200 healthy adults 18-65 years of age. Toxin-neutralizing antibody (TNA) was expressed as 50% neutralization factor (NF50) at predetermined time points through Day 100. Safety was assessed by physical examinations, vital signs, solicited local and systemic reactions using web-enabled subject diaries, in-clinic solicited reactions, and unsolicited adverse events (AEs). RESULTS The prospectively defined success criteria for the primary and secondary endpoints were met. This required the lower bound of the 95% confidence interval (CI) for the proportion of subjects with a TNA NF50 value to be greater than 40% at Day 63 (primary), Day 70 (secondary) and Days 63-100 (secondary). At Day 63, 71% of subjects achieved a TNA NF50 threshold value ≥ 0.56, with a lower bound of the 95% CI ≥ 40% (64%). The percentage of subjects achieving a TNA NF50 threshold value ≥ 0.56 at Day 70 was 58% (95% CI: 50%, 65%), and the mean value on Days 63-100 (inclusive) was 53% (95% CI: 41%, 55%). The threshold TNA NF50 value of 0.56 was developed from previous rabbit challenge and human immunogenicity studies. No related serious AEs occurred during the study, and no subjects withdrew from the study because of an AE. Tenderness and pain at the injection site were recorded most often in subject diaries following vaccination. CONCLUSIONS BioThrax, administered as three SC doses at 0, 2, and 4 weeks, was well tolerated. The prospectively defined success criteria for TNA levels on Days 63, 70, and 63-100 were achieved.
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Affiliation(s)
- Robert J Hopkins
- Clinical Development, Emergent BioSolutions, Gaithersburg, MD, USA.
| | - Cris Howard
- Clinical Development, Emergent BioSolutions, Gaithersburg, MD, USA
| | | | - Paulina E Kaptur
- Corporate Clinical and Medical Affairs, Emergent BioSolutions, Gaithersburg, MD, USA
| | - Brett Pleune
- Regulatory Affairs, Emergent BioSolutions, Gaithersburg, MD, USA.
| | - Derek Muse
- Jean Brown Research, Salt Lake City, UT, USA
| | | | - Matthew Davis
- Rochester Clinical Research Inc., Rochester, NY, USA
| | - Cynthia Strout
- Coastal Carolina Research Center, Mount Pleasant, SC, USA
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Intramuscular delivery of adenovirus serotype 5 vector expressing humanized protective antigen induces rapid protection against anthrax that may bypass intranasally originated preexisting adenovirus immunity. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2013; 21:156-64. [PMID: 24307239 DOI: 10.1128/cvi.00560-13] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Developing an effective anthrax vaccine that can induce a rapid and sustained immune response is a priority for the prevention of bioterrorism-associated anthrax infection. Here, we developed a recombinant replication-deficient adenovirus serotype 5-based vaccine expressing the humanized protective antigen (Ad5-PAopt). A single intramuscular injection of Ad5-PAopt resulted in rapid and robust humoral and cellular immune responses in Fisher 344 rats. Animals intramuscularly inoculated with a single dose of 10⁸ infectious units of Ad5-PAopt achieved 100% protection from challenge with 10 times the 50% lethal dose (LD₅₀) of anthrax lethal toxin 7 days after vaccination. Although preexisting intranasally induced immunity to Ad5 slightly weakened the humoral and cellular immune responses to Ad5-PAopt via intramuscular inoculation, 100% protection was achieved 15 days after vaccination in Fisher 344 rats. The protective efficacy conferred by intramuscular vaccination in the presence of preexisting intranasally induced immunity was significantly better than that of intranasal delivery of Ad5-PAopt and intramuscular injection with recombinant PA and aluminum adjuvant without preexisting immunity. As natural Ad5 infection often occurs via the mucosal route, the work here largely illuminates that intramuscular inoculation with Ad5-PAopt can overcome the negative effects of immunity induced by prior adenovirus infection and represents an efficient approach for protecting against emerging anthrax.
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Lu H, Catania J, Baranji K, Feng J, Gu M, Lathey J, Sweeny D, Sanford H, Sapru K, Patamawenu T, Chen JH, Ng A, Fesseha Z, Kluepfel-Stahl S, Minang J, Alleva D. Characterization of the native form of anthrax lethal factor for use in the toxin neutralization assay. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2013; 20:986-97. [PMID: 23637044 PMCID: PMC3697443 DOI: 10.1128/cvi.00046-13] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2013] [Accepted: 04/22/2013] [Indexed: 11/20/2022]
Abstract
The cell-based anthrax toxin neutralization assay (TNA) is used to determine functional antibody titers of sera from animals and humans immunized with anthrax vaccines. The anthrax lethal toxin is a critical reagent of the TNA composed of protective antigen (PA) and lethal factor (LF), which are neutralization targets of serum antibodies. Cytotoxic potency of recombinant LF (rLF) lots can vary substantially, causing a challenge in producing a renewable supply of this reagent for validated TNAs. To address this issue, we characterized a more potent rLF variant (rLF-A) with the exact native LF amino acid sequence that lacks the additional N-terminal histidine and methionine residues present on the commonly used form of rLF (rLF-HMA) as a consequence of the expression vector. rLF-A can be used at 4 to 6 ng/ml (in contrast to 40 ng/ml rLF-HMA) with 50 ng/ml recombinant PA (rPA) to achieve 95 to 99% cytotoxicity. In the presence of 50 ng/ml rPA, both rLF-A and rLF-HMA allowed for similar potencies (50% effective dilution) among immune sera in the TNA. rPA, but not rLF, was the dominant factor in determining potency of serum samples containing anti-PA antibodies only or an excess of anti-PA relative to anti-rLF antibodies. Such anti-PA content is reflected in immune sera derived from most anthrax vaccines in development. These results support that 7- to 10-fold less rLF-A can be used in place of rLF-HMA without changing TNA serum dilution curve parameters, thus extending the use of a single rLF lot and a consistent, renewable supply.
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Affiliation(s)
- Hang Lu
- Emergent BioSolutions, Inc., Gaithersburg, Maryland, USA
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Merkel TJ, Perera PY, Lee GM, Verma A, Hiroi T, Yokote H, Waldmann TA, Perera LP. Protective-antigen (PA) based anthrax vaccines confer protection against inhalation anthrax by precluding the establishment of a systemic infection. Hum Vaccin Immunother 2013; 9:1841-8. [PMID: 23787486 DOI: 10.4161/hv.25337] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
An intense effort has been launched to develop improved anthrax vaccines that confer rapid, long lasting protection preferably with an extended stability profile amenable for stockpiling. Protective antigen (PA)-based vaccines are most favored as immune responses directed against PA are singularly protective, although the actual protective mechanism remains to be unraveled. Herein we show that contrary to the prevailing view, an efficacious PA-based vaccine confers protection against inhalation anthrax by preventing the establishment of a toxin-releasing systemic infection. Equally importantly, antibodies measured by the in vitro lethal toxin neutralization activity assay (TNA) that is considered as a reliable correlate of protection, especially for PA protein-based vaccines adjuvanted with aluminum salts appear to be not absolutely essential for this protective immune response.
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Affiliation(s)
- Tod J Merkel
- Center for Biologics Evaluation and Research; Food and Drug Administration; Bethesda, MD USA
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Evaluation of immunogenicity and efficacy of anthrax vaccine adsorbed for postexposure prophylaxis. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2013; 20:1016-26. [PMID: 23658392 DOI: 10.1128/cvi.00099-13] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Antimicrobials administered postexposure can reduce the incidence or progression of anthrax disease, but they do not protect against the disease resulting from the germination of spores that may remain in the body after cessation of the antimicrobial regimen. Such additional protection may be achieved by postexposure vaccination; however, no anthrax vaccine is licensed for postexposure prophylaxis (PEP). In a rabbit PEP study, animals were subjected to lethal challenge with aerosolized Bacillus anthracis spores and then were treated with levofloxacin with or without concomitant intramuscular (i.m.) vaccination with anthrax vaccine adsorbed (AVA) (BioThrax; Emergent BioDefense Operations Lansing LLC, Lansing, MI), administered twice, 1 week apart. A significant increase in survival rates was observed among vaccinated animals compared to those treated with antibiotic alone. In preexposure prophylaxis studies in rabbits and nonhuman primates (NHPs), animals received two i.m. vaccinations 1 month apart and were challenged with aerosolized anthrax spores at day 70. Prechallenge toxin-neutralizing antibody (TNA) titers correlated with animal survival postchallenge and provided the means for deriving an antibody titer associated with a specific probability of survival in animals. In a clinical immunogenicity study, 82% of the subjects met or exceeded the prechallenge TNA value that was associated with a 70% probability of survival in rabbits and 88% probability of survival in NHPs, which was estimated based on the results of animal preexposure prophylaxis studies. The animal data provide initial information on protective antibody levels for anthrax, as well as support previous findings regarding the ability of AVA to provide added protection to B. anthracis-infected animals compared to antimicrobial treatment alone.
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Abstract
Because of a variety of caveats, the safety and effectiveness of interventions in human subjects can only be speculated from animal studies. Careful synthesis of data from multiple animal studies is needed to begin to assess the likelihood of successful cross-species translation (Fay et al., this issue).
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Affiliation(s)
- John P A Ioannidis
- Stanford Prevention Research Center, Department of Medicine, Stanford University School of Medicine, Stanford University School of Humanities and Sciences, Stanford, CA 94305, USA.
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