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Preston KB, Wong TAS, Lieberman MM, To A, Lai CY, Granados A, Thomasson H, Misamore J, Yalley-Ogunro J, Cabus M, Andersen H, Donini O, Lehrer AT, Randolph TW. Lyophilized Filovirus Glycoprotein Vaccines: Peroxides in a Vaccine Formulation with Polysorbate 80-Containing Adjuvant are Associated with Reduced Neutralizing Antibody Titers in Both Mice and Non-Human Primates. J Pharm Sci 2022; 111:3424-3434. [PMID: 35609629 DOI: 10.1016/j.xphs.2022.05.017] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Revised: 05/18/2022] [Accepted: 05/18/2022] [Indexed: 01/05/2023]
Abstract
Zaire ebolavirus, Sudan ebolavirus, and Marburg marburgvirus are the filoviruses most commonly associated with human disease. Previously, we administered a three-dose regimen of trivalent vaccines comprising glycoprotein antigens from each virus in mice and non-human primates (NHPs). The vaccines, which contained a polysorbate 80-stabilized squalane-in-water emulsion adjuvant and were lyophilized from a solution containing trehalose, produced high antibody levels against all three filovirus antigens. Subsequently, single-vial formulations containing a higher concentration of adjuvant were generated for testing in NHPs, but these vaccines elicited lower neutralizing antibody titers in NHPs than previously tested formulations. In order to explain these results, in the current work we measured the size of adjuvant emulsion droplets and the peroxide levels present in the vaccines after lyophilization and reconstitution and tested the effects of these variables on the immune response in mice. Increases in squalane droplet sizes were observed when the ratio of adjuvant to trehalose was increased beyond a critical value, but antibody and neutralizing antibody titers in mice were independent of the droplet size. Higher levels of peroxides in the vaccines correlated with higher concentrations of adjuvant in the formulations, and higher peroxide levels were associated with increased levels of oxidative damage to glycoprotein antigens. Neutralizing titers in mice were inversely correlated with peroxide levels in the vaccines, but peroxide levels could be reduced by adding free methionine, resulting in retention of high neutralizing antibody titers. Overall, the results suggest that oxidation of glycoprotein antigens by peroxides in the polysorbate 80-stabilized squalane-in-water emulsion adjuvant, but not lyophilization-induced increases in adjuvant emulsion droplet size may have been responsible for the decreased neutralizing titers seen in formulations containing higher amounts of adjuvant.
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Affiliation(s)
- Kendall B Preston
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, CO 80303, United States
| | - Teri Ann S Wong
- Department of Tropical Medicine, Medical Microbiology & Pharmacology, John A. Burns School of Medicine, University of Hawai'i at Manoa, Honolulu, HI 96813, United States
| | - Michael M Lieberman
- Department of Tropical Medicine, Medical Microbiology & Pharmacology, John A. Burns School of Medicine, University of Hawai'i at Manoa, Honolulu, HI 96813, United States
| | - Albert To
- Department of Tropical Medicine, Medical Microbiology & Pharmacology, John A. Burns School of Medicine, University of Hawai'i at Manoa, Honolulu, HI 96813, United States
| | - Chih-Yun Lai
- Department of Tropical Medicine, Medical Microbiology & Pharmacology, John A. Burns School of Medicine, University of Hawai'i at Manoa, Honolulu, HI 96813, United States
| | | | | | | | | | - Mehtap Cabus
- BIOQUAL, Inc., Rockville, MD 20850, United States
| | | | | | - Axel T Lehrer
- Department of Tropical Medicine, Medical Microbiology & Pharmacology, John A. Burns School of Medicine, University of Hawai'i at Manoa, Honolulu, HI 96813, United States
| | - Theodore W Randolph
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, CO 80303, United States.
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2
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Freeze-drying: A Flourishing Strategy to Fabricate Stable Pharmaceutical and Biological Products. Int J Pharm 2022; 628:122233. [DOI: 10.1016/j.ijpharm.2022.122233] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Revised: 09/07/2022] [Accepted: 09/20/2022] [Indexed: 11/21/2022]
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3
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Han S, Li H, Chen W, Yang L, Tong X, Zuo J, Hu Y. Discovery of potent ebola entry inhibitors with (3S,4aS,8aS)-2-(3-amino-2-hydroxypropyl) decahydroisoquinoline-3-carboxamide scaffold. Eur J Med Chem 2022; 240:114608. [PMID: 35872393 DOI: 10.1016/j.ejmech.2022.114608] [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: 06/07/2022] [Revised: 07/03/2022] [Accepted: 07/10/2022] [Indexed: 11/15/2022]
Abstract
Ebola virus (EBOV), one member of the family Filoviridae, can causes hemorrhagic fever and other severe diseases in humans with a high mortality rate (25-90%). Until recently, there were no approved drugs and very limited treatment method for Ebola virus disease. In this study, we discovered a series of potent Ebola entry inhibitors with the (3S,4aS,8aS)-2-(3-amino-2-hydroxypropyl)decahydroisoquinoline-3-carboxamide scaffold from high-throughput screening in reported pseudotyped virus system. Further optimization resulted a most potent compound 28 (IC50= 0.05 μM, SI = 98), which displayed 3-fold potency compared to the known inhibitor Toremifene (IC50= 0.17 μM, SI = 55). Moreover, compound 28 exhibited the remarkable selectivity between EBOV-GP and VSV-G (Spec. Index = 58), thus could exclude nonspecific effects. Structure-activity relationship and molecular docking analysis of the new chemical scaffold provided more information on the binding modes and the spare volume at the binding cavity, thus can guide the design of the further potent compounds.
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Affiliation(s)
- Sheng Han
- State Key Laboratory of Drug Research, Department of Medicinal Chemistry, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai, 201203, China
| | - Heng Li
- Immunological Disease Research Center, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Weixiong Chen
- School of Chinese Materia Medica, Nanjing University of Chinese Medicine, Nanjing, 210023, China
| | - Li Yang
- Immunological Disease Research Center, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China
| | - Xiankun Tong
- Immunological Disease Research Center, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China.
| | - Jianping Zuo
- Immunological Disease Research Center, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China; Laboratory of Immunology and Virology, Shanghai University of Traditional Chinese Medicine, Shanghai, 201203, China.
| | - Youhong Hu
- State Key Laboratory of Drug Research, Department of Medicinal Chemistry, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai, 201203, China; School of Chinese Materia Medica, Nanjing University of Chinese Medicine, Nanjing, 210023, China; School of Pharmaceutical Science and Technology, Hangzhou Institute for Advanced Study, UCAS, 1 Xiangshanzhi Road, Hangzhou, 310024, China.
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4
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Ding Y, Li Z, Jaklenec A, Hu Q. Vaccine delivery systems toward lymph nodes. Adv Drug Deliv Rev 2021; 179:113914. [PMID: 34363861 PMCID: PMC9418125 DOI: 10.1016/j.addr.2021.113914] [Citation(s) in RCA: 58] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Revised: 07/05/2021] [Accepted: 07/31/2021] [Indexed: 12/15/2022]
Abstract
Strategies of improving vaccine targeting ability toward lymph nodes have been attracting considerable interest in recent years, though there are remaining delivery barriers based on the inherent properties of lymphatic systems and limited administration routes of vaccination. Recently, emerging vaccine delivery systems using various materials as carriers are widely developed to achieve efficient lymph node targeting and improve vaccine-triggered adaptive immune response. In this review, to further optimize the vaccine targeting ability for future research, the design principles of lymph node targeting vaccine delivery based on the anatomy of lymph nodes and vaccine administration routes are first summarized. Then different designs of lymph node targeting vaccine delivery systems, including vaccine delivery systems in clinical applications, are carefully surveyed. Also, the challenges and opportunities of current delivery systems for vaccines are concluded in the end.
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Affiliation(s)
- Yingyue Ding
- Pharmaceutical Sciences Division, School of Pharmacy, University of Wisconsin-Madison, Madison, WI 53705, United States,Carbone Cancer Center, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI 53705, United States
| | - Zhaoting Li
- Pharmaceutical Sciences Division, School of Pharmacy, University of Wisconsin-Madison, Madison, WI 53705, United States,Carbone Cancer Center, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI 53705, United States
| | - Ana Jaklenec
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02142, United States
| | - Quanyin Hu
- Pharmaceutical Sciences Division, School of Pharmacy, University of Wisconsin-Madison, Madison, WI 53705, United States; Carbone Cancer Center, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI 53705, United States.
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5
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Lai CY, To A, Wong TAS, Lieberman MM, Clements DE, Senda JT, Ball AH, Pessaint L, Andersen H, Furuyama W, Marzi A, Donini O, Lehrer AT. Recombinant protein subunit SARS-CoV-2 vaccines formulated with CoVaccine HT adjuvant induce broad, Th1 biased, humoral and cellular immune responses in mice. Vaccine X 2021; 9:100126. [PMID: 34778744 PMCID: PMC8570651 DOI: 10.1016/j.jvacx.2021.100126] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Revised: 10/20/2021] [Accepted: 10/29/2021] [Indexed: 12/23/2022] Open
Abstract
The speed at which several COVID-19 vaccines went from conception to receiving FDA and EMA approval for emergency use is an achievement unrivaled in the history of vaccine development. Mass vaccination efforts using the highly effective vaccines are currently underway to generate sufficient herd immunity and reduce transmission of the SARS-CoV-2 virus. Despite the most advanced vaccine technology, global recipient coverage, especially in resource-poor areas remains a challenge as genetic drift in naïve population pockets threatens overall vaccine efficacy. In this study, we described the production of insect-cell expressed SARS-CoV-2 spike protein ectodomain constructs and examined their immunogenicity in mice. We demonstrated that, when formulated with CoVaccine HTTM adjuvant, an oil-in-water nanoemulsion compatible with lyophilization, our vaccine candidates elicit a broad-spectrum IgG response, high neutralizing antibody (NtAb) titers against SARS-CoV-2 prototype and variants of concern, specifically B.1.351 (Beta) and P.1. (Gamma), and an antigen-specific IFN-γ secreting response in outbred mice. Of note, different ectodomain constructs yielded variations in NtAb titers against the prototype strain and some VOC. Dose response experiments indicated that NtAb titers increased with antigen dose, but not adjuvant dose, and may be higher with a lower adjuvant dose. Our findings lay the immunological foundation for the development of a dry-thermostabilized vaccine that is deployable without refrigeration.
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Affiliation(s)
- Chih-Yun Lai
- Department of Tropical Medicine, Medical Microbiology, and Pharmacology,
John A. Burns School of Medicine, University of Hawaii at Manoa, Honolulu, HI,
USA
- Pacific Center for Emerging Infectious Disease Research, John A. Burns
School of Medicine, University of Hawaii at Manoa, Honolulu, HI, USA
| | - Albert To
- Department of Tropical Medicine, Medical Microbiology, and Pharmacology,
John A. Burns School of Medicine, University of Hawaii at Manoa, Honolulu, HI,
USA
| | - Teri Ann S. Wong
- Department of Tropical Medicine, Medical Microbiology, and Pharmacology,
John A. Burns School of Medicine, University of Hawaii at Manoa, Honolulu, HI,
USA
| | - Michael M. Lieberman
- Department of Tropical Medicine, Medical Microbiology, and Pharmacology,
John A. Burns School of Medicine, University of Hawaii at Manoa, Honolulu, HI,
USA
| | | | | | - Aquena H. Ball
- Department of Tropical Medicine, Medical Microbiology, and Pharmacology,
John A. Burns School of Medicine, University of Hawaii at Manoa, Honolulu, HI,
USA
| | | | | | - Wakako Furuyama
- Laboratory of Virology, Division of Intramural Research, NIAID, NIH,
Hamilton, Montana, MT, USA
| | - Andrea Marzi
- Laboratory of Virology, Division of Intramural Research, NIAID, NIH,
Hamilton, Montana, MT, USA
| | | | - Axel T. Lehrer
- Department of Tropical Medicine, Medical Microbiology, and Pharmacology,
John A. Burns School of Medicine, University of Hawaii at Manoa, Honolulu, HI,
USA
- Pacific Center for Emerging Infectious Disease Research, John A. Burns
School of Medicine, University of Hawaii at Manoa, Honolulu, HI, USA
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6
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Preston KB, Wong TAS, To A, Tashiro TE, Lieberman MM, Granados A, Feliciano K, Harrison J, Yalley-Ogunro J, Elyard HA, Donini O, Lehrer AT, Randolph TW. Single-vial filovirus glycoprotein vaccines: Biophysical characteristics and immunogenicity after co-lyophilization with adjuvant. Vaccine 2021; 39:5650-5657. [PMID: 34400019 DOI: 10.1016/j.vaccine.2021.08.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 07/23/2021] [Accepted: 08/02/2021] [Indexed: 10/20/2022]
Abstract
Zaire ebolavirus (EBOV), Sudan ebolavirus (SUDV), and Marburg marburgvirus (MARV) are the most prevalent and pathogenic species of filovirus. Previously, we showed that glycoprotein antigens from each virus could be lyophilized to create thermostable monovalent subunit vaccines. However, cross-protection is not expected from the monovalent vaccines and therefore developing a trivalent filovirus vaccine would be desirable. Subunit protein vaccines often require the addition of an adjuvant to sufficiently boost the immunogenicity. Typically, liquid suspensions or emulsions of adjuvants and lyophilized antigens are stored in separate vials to avoid destabilizing interactions and are only mixed immediately before administration. Herein, we describe the development and characterization of monovalent and trivalent filovirus vaccines that are co-lyophilized with a squalane-in-water emulsion adjuvant. We found that the single-vial presentation retained adjuvant particle diameter and zeta potential after lyophilization and reconstitution. Furthermore, the trivalent vaccines elicited high antibody levels against all three antigens in mice and non-human primates. These results advance the prospect of developing a single-vial trivalent filovirus vaccine, which would enable easier distribution and administration of the vaccine to resource-poor areas.
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Affiliation(s)
- Kendall B Preston
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, CO 80303, United States
| | - Teri Ann S Wong
- Department of Tropical Medicine, Medical Microbiology & Pharmacology, John A. Burns School of Medicine, University of Hawai'i at Manoa, Honolulu, HI 96813, United States
| | - Albert To
- Department of Tropical Medicine, Medical Microbiology & Pharmacology, John A. Burns School of Medicine, University of Hawai'i at Manoa, Honolulu, HI 96813, United States
| | - Taylor E Tashiro
- Department of Tropical Medicine, Medical Microbiology & Pharmacology, John A. Burns School of Medicine, University of Hawai'i at Manoa, Honolulu, HI 96813, United States
| | - Michael M Lieberman
- Department of Tropical Medicine, Medical Microbiology & Pharmacology, John A. Burns School of Medicine, University of Hawai'i at Manoa, Honolulu, HI 96813, United States
| | | | | | | | | | | | | | - Axel T Lehrer
- Department of Tropical Medicine, Medical Microbiology & Pharmacology, John A. Burns School of Medicine, University of Hawai'i at Manoa, Honolulu, HI 96813, United States
| | - Theodore W Randolph
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, CO 80303, United States.
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7
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Lehrer AT, Chuang E, Namekar M, Williams CA, Wong TAS, Lieberman MM, Granados A, Misamore J, Yalley-Ogunro J, Andersen H, Geisbert JB, Agans KN, Cross RW, Geisbert TW. Recombinant Protein Filovirus Vaccines Protect Cynomolgus Macaques From Ebola, Sudan, and Marburg Viruses. Front Immunol 2021; 12:703986. [PMID: 34484200 PMCID: PMC8416446 DOI: 10.3389/fimmu.2021.703986] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2021] [Accepted: 07/29/2021] [Indexed: 11/23/2022] Open
Abstract
Ebola (EBOV), Marburg (MARV) and Sudan (SUDV) viruses are the three filoviruses which have caused the most fatalities in humans. Transmission from animals into the human population typically causes outbreaks of limited scale in endemic regions. In contrast, the 2013-16 outbreak in several West African countries claimed more than 11,000 lives revealing the true epidemic potential of filoviruses. This is further emphasized by the difficulty seen with controlling the 2018-2020 outbreak of EBOV in the Democratic Republic of Congo (DRC), despite the availability of two emergency use-approved vaccines and several experimental therapeutics targeting EBOV. Moreover, there are currently no vaccine options to protect against the other epidemic filoviruses. Protection of a monovalent EBOV vaccine against other filoviruses has never been demonstrated in primate challenge studies substantiating a significant void in capability should a MARV or SUDV outbreak of similar magnitude occur. Herein we show progress on developing vaccines based on recombinant filovirus glycoproteins (GP) from EBOV, MARV and SUDV produced using the Drosophila S2 platform. The highly purified recombinant subunit vaccines formulated with CoVaccine HT™ adjuvant have not caused any safety concerns (no adverse reactions or clinical chemistry abnormalities) in preclinical testing. Candidate formulations elicit potent immune responses in mice, guinea pigs and non-human primates (NHPs) and consistently produce high antigen-specific IgG titers. Three doses of an EBOV candidate vaccine elicit full protection against lethal EBOV infection in the cynomolgus challenge model while one of four animals infected after only two doses showed delayed onset of Ebola Virus Disease (EVD) and eventually succumbed to infection while the other three animals survived challenge. The monovalent MARV or SUDV vaccine candidates completely protected cynomolgus macaques from infection with lethal doses of MARV or SUDV. It was further demonstrated that combinations of MARV or SUDV with the EBOV vaccine can be formulated yielding bivalent vaccines retaining full efficacy. The recombinant subunit vaccine platform should therefore allow the development of a safe and efficacious multivalent vaccine candidate for protection against Ebola, Marburg and Sudan Virus Disease.
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Affiliation(s)
- Axel T. Lehrer
- Department of Tropical Medicine, Medical Microbiology & Pharmacology, John A. Burns School of Medicine, University of Hawaii at Manoa, Honolulu, HI, United States
| | - Eleanore Chuang
- Department of Tropical Medicine, Medical Microbiology & Pharmacology, John A. Burns School of Medicine, University of Hawaii at Manoa, Honolulu, HI, United States
| | - Madhuri Namekar
- Department of Tropical Medicine, Medical Microbiology & Pharmacology, John A. Burns School of Medicine, University of Hawaii at Manoa, Honolulu, HI, United States
| | - Caitlin A. Williams
- Department of Tropical Medicine, Medical Microbiology & Pharmacology, John A. Burns School of Medicine, University of Hawaii at Manoa, Honolulu, HI, United States
| | - Teri Ann S. Wong
- Department of Tropical Medicine, Medical Microbiology & Pharmacology, John A. Burns School of Medicine, University of Hawaii at Manoa, Honolulu, HI, United States
| | - Michael M. Lieberman
- Department of Tropical Medicine, Medical Microbiology & Pharmacology, John A. Burns School of Medicine, University of Hawaii at Manoa, Honolulu, HI, United States
| | | | | | | | | | - Joan B. Geisbert
- Galveston National Laboratory, Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX, United States
| | - Krystle N. Agans
- Galveston National Laboratory, Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX, United States
| | - Robert W. Cross
- Galveston National Laboratory, Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX, United States
| | - Thomas W. Geisbert
- Galveston National Laboratory, Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX, United States
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8
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Preston KB, Randolph TW. Stability of lyophilized and spray dried vaccine formulations. Adv Drug Deliv Rev 2021; 171:50-61. [PMID: 33484735 DOI: 10.1016/j.addr.2021.01.016] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Revised: 01/13/2021] [Accepted: 01/14/2021] [Indexed: 12/16/2022]
Abstract
Liquid formulations of vaccines are subject to instabilities that result from degradation processes that proceed via a variety of physical and chemical pathways. In dried formulations, such as those prepared by lyophilization or spray drying, many of these degradation pathways may be avoided or inhibited. Thus, the stability of vaccine formulations can be enhanced significantly in the absence of bulk water. Potential advantages of dry vaccine formulations include extended shelf lives and less stringent cold-chain storage requirements, both of which offer possibilities of reduced vaccine wastage and facilitated distribution to resource-poor areas. Lyophilization and spray drying represent the most common methods of stabilizing vaccines through drying. This article reviews several lyophilized and spray dried vaccines that address a diverse set of pathogens, as well as some of the assays used to quantify their stability. Recent dry vaccine trends include needle-free delivery of dry powder via non-parenteral routes of administration and the incorporation of advanced vaccine adjuvants into formulations, which further contribute to the goal of increasing vaccine distribution to resource-poor areas. Challenges associated with development of these newer technologies are also discussed.
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Affiliation(s)
- Kendall B Preston
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, CO 80303, United States of America
| | - Theodore W Randolph
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, CO 80303, United States of America.
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9
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Lai CY, To A, Wong TAS, Lieberman MM, Clements DE, Senda JT, Ball AH, Pessaint L, Andersen H, Donini O, Lehrer AT. Recombinant protein subunit SARS-CoV-2 vaccines formulated with CoVaccine HT adjuvant induce broad, Th1 biased, humoral and cellular immune responses in mice. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2021. [PMID: 33688645 DOI: 10.1101/2021.03.02.433614] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The speed at which several COVID-19 vaccines went from conception to receiving FDA and EMA approval for emergency use is an achievement unrivaled in the history of vaccine development. Mass vaccination efforts using the highly effective vaccines are currently underway to generate sufficient herd immunity and reduce transmission of the SARS-CoV-2 virus. Despite the most advanced vaccine technology, global recipient coverage, especially in resource-poor areas remains a challenge as genetic drift in naïve population pockets threatens overall vaccine efficacy. In this study, we described the production of insect-cell expressed SARS-CoV-2 spike protein ectodomain and examined its immunogenicity in mice. We demonstrated that, when formulated with CoVaccine HT™adjuvant, an oil-in-water nanoemulsion compatible with lyophilization, our vaccine candidates elicit a broad-spectrum IgG response, high neutralizing antibody titers, and a robust, antigen-specific IFN-γ secreting response from immune splenocytes in outbred mice. Our findings lay the foundation for the development of a dry-thermostabilized vaccine that is deployable without refrigeration.
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