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Bottazzi ME, Miles AP, Diemert D, Hotez PJ. An ounce of prevention on a budget: a nonprofit approach to developing vaccines against neglected diseases. Expert Rev Vaccines 2014; 5:189-98. [PMID: 16608419 DOI: 10.1586/14760584.5.2.189] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
This article provides a perspective on vaccine development for neglected tropical diseases in the nonprofit setting, with particular emphasis on recombinant protein vaccines. The Human Hookworm Vaccine Initiative is discussed as a model product development public-private partnership, and the major challenges are covered that accompany antigen selection, gene cloning, fermentation and purification process development, assay development, vaccine formulation and testing and clinical evaluation for those developing vaccines, especially against neglected tropical diseases, in the nonprofit sector. Throughout this perspective, special emphasis is placed on the growing promise that product development public-private partnerships hold for developing vaccines for the world's poorest people.
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Affiliation(s)
- Maria Elena Bottazzi
- The George Washington University, The Human Hookworm Vaccine Initiative, Department of Microbiology, Immunology and Tropical Medicine, 2300 Eye Street NW, Ross Hall Room 733, Washington, DC 20037, USA.
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Pearson MS, Bethony JM, Pickering DA, de Oliveira LM, Jariwala A, Santiago H, Miles AP, Zhan B, Jiang D, Ranjit N, Mulvenna J, Tribolet L, Plieskatt J, Smith T, Bottazzi ME, Jones K, Keegan B, Hotez PJ, Loukas A. An enzymatically inactivated hemoglobinase from Necator americanus induces neutralizing antibodies against multiple hookworm species and protects dogs against heterologous hookworm infection. FASEB J 2009; 23:3007-19. [PMID: 19380510 PMCID: PMC2735369 DOI: 10.1096/fj.09-131433] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Hookworms digest hemoglobin from erythrocytes via a proteolytic cascade that begins with the aspartic protease, APR-1. Ac-APR-1 from the dog hookworm, Ancylostoma caninum, protects dogs against hookworm infection via antibodies that neutralize enzymatic activity and interrupt blood-feeding. Toward developing a human hookworm vaccine, we expressed both wild-type (Na-APR-1wt) and mutant (Na-APR-1mut—mutagenesis of the catalytic aspartic acids) forms of Na-APR-1 from the human hookworm, Necator americanus. Refolded Na-APR-1wt was catalytically active, and Na-APR-1mut was catalytically inactive but still bound substrates. Vaccination of canines with Na-APR-1mut and heterologous challenge with A. caninum resulted in significantly reduced parasite egg burdens (P=0.034) and weight loss (P=0.022). Vaccinated dogs also had less gut pathology, fewer adult worms, and reduced blood loss compared to controls but these did not reach statistical significance. Vaccination with Na-APR-1mut induced antibodies that bound the native enzyme in the parasite gut and neutralized enzymatic activity of Na-APR-1wt and APR-1 orthologues from three other hookworm species that infect humans. IgG1 against Na-APR-1mut was the most prominently detected antibody in sera from people resident in high-transmission areas for N. americanus, indicating that natural boosting may occur in exposed humans. Na-APR-1mut is now a lead antigen for the development of an antihematophagy vaccine for human hookworm disease.—Pearson, M. S., Bethony, J. M., Pickering, D. A., de Oliveira, L. M., Jariwala, A., Santiago, H., Miles, A. P., Zhan, B., Jiang, D., Ranjit, N., Mulvenna, J., Tribolet, L., Plieskatt, J., Smith, T., Bottazzi, M. E., Jones, K., Keegan, B., Hotez, P. J., Loukas, A. An enzymatically inactivated hemoglobinase from Necator americanus induces neutralizing antibodies against multiple hookworm species and protects dogs against heterologous hookworm infection.
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Affiliation(s)
- Mark S Pearson
- Division of Infectious Diseases, Queensland Institute of Medical Research and The Australian Centre for Vaccine Development, Brisbane, Australia
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Wu Y, Ellis RD, Shaffer D, Fontes E, Malkin EM, Mahanty S, Fay MP, Narum D, Rausch K, Miles AP, Aebig J, Orcutt A, Muratova O, Song G, Lambert L, Zhu D, Miura K, Long C, Saul A, Miller LH, Durbin AP. Phase 1 trial of malaria transmission blocking vaccine candidates Pfs25 and Pvs25 formulated with montanide ISA 51. PLoS One 2008; 3:e2636. [PMID: 18612426 PMCID: PMC2440546 DOI: 10.1371/journal.pone.0002636] [Citation(s) in RCA: 294] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2008] [Accepted: 06/04/2008] [Indexed: 11/18/2022] Open
Abstract
Background Pfs25 and Pvs25, surface proteins of mosquito stage of the malaria parasites P. falciparum and P. vivax, respectively, are leading candidates for vaccines preventing malaria transmission by mosquitoes. This single blinded, dose escalating, controlled Phase 1 study assessed the safety and immunogenicity of recombinant Pfs25 and Pvs25 formulated with Montanide ISA 51, a water-in-oil emulsion. Methodology/Principal Findings The trial was conducted at The Johns Hopkins Center for Immunization Research, Washington DC, USA, between May 16, 2005–April 30, 2007. The trial was designed to enroll 72 healthy male and non-pregnant female volunteers into 1 group to receive adjuvant control and 6 groups to receive escalating doses of the vaccines. Due to unexpected reactogenicity, the vaccination was halted and only 36 volunteers were enrolled into 4 groups: 3 groups of 10 volunteers each were immunized with 5 µg of Pfs25/ISA 51, 5 µg of Pvs25/ISA 51, or 20 µg of Pvs25/ISA 51, respectively. A fourth group of 6 volunteers received adjuvant control (PBS/ISA 51). Frequent local reactogenicity was observed. Systemic adverse events included two cases of erythema nodosum considered to be probably related to the combination of the antigen and the adjuvant. Significant antibody responses were detected in volunteers who completed the lowest scheduled doses of Pfs25/ISA 51. Serum anti-Pfs25 levels correlated with transmission blocking activity. Conclusion/Significance It is feasible to induce transmission blocking immunity in humans using the Pfs25/ISA 51 vaccine, but these vaccines are unexpectedly reactogenic for further development. This is the first report that the formulation is associated with systemic adverse events including erythema nodosum. Trial Registration ClinicalTrials.gov NCT00295581
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MESH Headings
- Adolescent
- Adult
- Animals
- Antigens, Protozoan/chemistry
- Antigens, Protozoan/immunology
- Antigens, Surface/chemistry
- Antigens, Surface/immunology
- Disease Transmission, Infectious
- Female
- Humans
- Malaria Vaccines/adverse effects
- Malaria Vaccines/chemistry
- Malaria Vaccines/immunology
- Malaria, Falciparum/prevention & control
- Malaria, Falciparum/transmission
- Malaria, Vivax/prevention & control
- Malaria, Vivax/transmission
- Male
- Mannitol/administration & dosage
- Mannitol/analogs & derivatives
- Mannitol/chemistry
- Middle Aged
- Oleic Acids/administration & dosage
- Oleic Acids/chemistry
- Plasmodium falciparum/immunology
- Plasmodium vivax/immunology
- Protozoan Proteins/adverse effects
- Protozoan Proteins/chemistry
- Protozoan Proteins/immunology
- Recombinant Proteins/adverse effects
- Recombinant Proteins/immunology
- Vaccines, Synthetic/administration & dosage
- Vaccines, Synthetic/chemistry
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Affiliation(s)
- Yimin Wu
- Malaria Vaccine Development Branch, National Institute of Allergy and Infectious Diseases, Rockville, Maryland, United States of America
- * E-mail: (YW); (AD)
| | - Ruth D. Ellis
- Malaria Vaccine Development Branch, National Institute of Allergy and Infectious Diseases, Rockville, Maryland, United States of America
| | - Donna Shaffer
- Center for Immunization Research, Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
| | - Erica Fontes
- Center for Immunization Research, Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
| | - Elissa M. Malkin
- Malaria Vaccine Development Branch, National Institute of Allergy and Infectious Diseases, Rockville, Maryland, United States of America
| | - Siddhartha Mahanty
- Malaria Vaccine Development Branch, National Institute of Allergy and Infectious Diseases, Rockville, Maryland, United States of America
| | - Michael P. Fay
- Biostatistics Research Branch, National Institute of Allergy and Infectious Diseases, Bethesda, Maryland, United States of America
| | - David Narum
- Malaria Vaccine Development Branch, National Institute of Allergy and Infectious Diseases, Rockville, Maryland, United States of America
| | - Kelly Rausch
- Malaria Vaccine Development Branch, National Institute of Allergy and Infectious Diseases, Rockville, Maryland, United States of America
| | - Aaron P. Miles
- Malaria Vaccine Development Branch, National Institute of Allergy and Infectious Diseases, Rockville, Maryland, United States of America
| | - Joan Aebig
- Malaria Vaccine Development Branch, National Institute of Allergy and Infectious Diseases, Rockville, Maryland, United States of America
| | - Andrew Orcutt
- Malaria Vaccine Development Branch, National Institute of Allergy and Infectious Diseases, Rockville, Maryland, United States of America
| | - Olga Muratova
- Malaria Vaccine Development Branch, National Institute of Allergy and Infectious Diseases, Rockville, Maryland, United States of America
| | - Guanhong Song
- Malaria Vaccine Development Branch, National Institute of Allergy and Infectious Diseases, Rockville, Maryland, United States of America
| | - Lynn Lambert
- Malaria Vaccine Development Branch, National Institute of Allergy and Infectious Diseases, Rockville, Maryland, United States of America
| | - Daming Zhu
- Malaria Vaccine Development Branch, National Institute of Allergy and Infectious Diseases, Rockville, Maryland, United States of America
| | - Kazutoyo Miura
- Malaria Vaccine Development Branch, National Institute of Allergy and Infectious Diseases, Rockville, Maryland, United States of America
| | - Carole Long
- Malaria Vaccine Development Branch, National Institute of Allergy and Infectious Diseases, Rockville, Maryland, United States of America
| | - Allan Saul
- Malaria Vaccine Development Branch, National Institute of Allergy and Infectious Diseases, Rockville, Maryland, United States of America
| | - Louis H. Miller
- Malaria Vaccine Development Branch, National Institute of Allergy and Infectious Diseases, Rockville, Maryland, United States of America
| | - Anna P. Durbin
- Center for Immunization Research, Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
- * E-mail: (YW); (AD)
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Mullen GED, Aebig JA, Dobrescu G, Rausch K, Lambert L, Long CA, Miles AP, Saul A. Enhanced antibody production in mice to the malaria antigen AMA1 by CPG 7909 requires physical association of CpG and antigen. Vaccine 2007; 25:5343-7. [PMID: 17566616 PMCID: PMC1997297 DOI: 10.1016/j.vaccine.2007.05.007] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2007] [Revised: 04/27/2007] [Accepted: 05/09/2007] [Indexed: 11/29/2022]
Abstract
CpG oligodeoxynucleotides are potent immunostimulants. In this study, CPG 7909 was formulated with the recombinant Plasmodium falciparum protein AMA1-C1 adsorbed to Alhydrogel (aluminum hydroxide) and used to immunize mice. Mice receiving free CPG 7909 in a separate same site injection to the AMA1-C1/Alhydrogel had the same antibody responses as mice receiving AMA1-C1/Alhydrogel alone. For mice immunized with CPG 7909 bound to the AMA1-C1/Alhydrogel formulation, there was a bell shaped CPG 7909 dose-response curve with the highest antibody response co-incident with the concentration of CPG 7909 that saturated binding to the Alhydrogel. At a higher CPG 7909 dose where 74% was unbound, there was no enhancement of response over AMA1-C1/Alhydrogel alone. Our results suggest that the adjuvant effects of CpGs are optimal when adsorbed to Alhydrogel and highlight the need for careful characterization of the vaccine formulation.
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Affiliation(s)
| | - Joan A. Aebig
- *Corresponding author. Phone: 301-435-2936. Fax: 301-480-1962. E-mail:
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Malkin E, Long CA, Stowers AW, Zou L, Singh S, MacDonald NJ, Narum DL, Miles AP, Orcutt AC, Muratova O, Moretz SE, Zhou H, Diouf A, Fay M, Tierney E, Leese P, Mahanty S, Miller LH, Saul A, Martin LB. Phase 1 study of two merozoite surface protein 1 (MSP1(42)) vaccines for Plasmodium falciparum malaria. PLoS Clin Trials 2007; 2:e12. [PMID: 17415408 PMCID: PMC1847697 DOI: 10.1371/journal.pctr.0020012] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/02/2006] [Accepted: 02/07/2007] [Indexed: 11/19/2022]
Abstract
Objectives: To assess the safety and immunogenicity of two vaccines, MSP142-FVO/Alhydrogel and MSP142-3D7/Alhydrogel, targeting blood-stage Plasmodium falciparum parasites. Design: A Phase 1 open-label, dose-escalating study. Setting: Quintiles Phase 1 Services, Lenexa, Kansas between July 2004 and November 2005. Participants: Sixty healthy malaria-naïve volunteers 18–48 y of age. Interventions: The C-terminal 42-kDa region of merozoite surface protein 1 (MSP142) corresponding to the two allelic forms present in FVO and 3D7 P. falciparum lines were expressed in Escherichia coli, refolded, purified, and formulated on Alhydrogel (aluminum hydroxide). For each vaccine, volunteers in each of three dose cohorts (5, 20, and 80 μg) were vaccinated at 0, 28, and 180 d. Volunteers were followed for 1 y. Outcome Measures: The safety of MSP142-FVO/Alhydrogel and MSP142-3D7/Alhydrogel was assessed. The antibody response to each vaccine was measured by reactivity to homologous and heterologous MSP142, MSP119, and MSP133 recombinant proteins and recognition of FVO and 3D7 parasites. Results: Anti-MSP142 antibodies were detected by ELISA in 20/27 (74%) and 22/27 (81%) volunteers receiving three vaccinations of MSP142-FVO/Alhydrogel or MSP142-3D7/Alhydrogel, respectively. Regardless of the vaccine, the antibodies were cross-reactive to both MSP142-FVO and MSP142-3D7 proteins. The majority of the antibody response targeted the C-terminal 19-kDa domain of MSP142, although low-level antibodies to the N-terminal 33-kDa domain of MSP142 were also detected. Immunofluorescence microscopy of sera from the volunteers demonstrated reactivity with both FVO and 3D7 P. falciparum schizonts and free merozoites. Minimal in vitro growth inhibition of FVO or 3D7 parasites by purified IgG from the sera of the vaccinees was observed. Conclusions: The MSP142/Alhydrogel vaccines were safe and well tolerated but not sufficiently immunogenic to generate a biologic effect in vitro. Addition of immunostimulants to the Alhydrogel formulation to elicit higher vaccine-induced responses in humans may be required for an effective vaccine. Background: Generally, adults living in parts of the world where malaria is common develop protective immunity against the parasite. This means they may get infected but not become ill as a result. However, there are individuals, such as pregnant women and children under the age of five, who are more likely to develop symptoms of malaria due to no (or reduced) natural immunity. A successful malaria vaccine would stimulate an individual's immune system to respond to the malaria parasite and prevent serious clinical disease. Many different groups are currently developing potential vaccines. Several candidates are based on a protein called MSP1 (merozoite surface protein 1) which is found on the surface of the blood-stage form of the malaria parasite. However, in nature parasites carry different versions of the MSP1 protein, and ideally a successful vaccine would bring about immune responses against these different versions. The researchers carrying out this trial wanted to compare the safety and immune responses against candidate vaccines representing two different MSP1 proteins, which covered many different parasite lines. As a phase 1 trial, the study was carried out in healthy adult volunteers. Sixty individuals were assigned to receive an injection of the vaccines, either containing a recombinant protein analogous to the FVO parasite line (termed MSP142-FVO) or the 3D7 parasite line (termed MSP142-3D7) at three different dose levels. The trial's primary objective was to assess safety, which was done by collecting data on any abnormal signs or symptoms up to 14 d after each of three vaccinations. These outcomes were graded and then defined as related to the vaccine or not. The researchers also looked at antibody levels in participants' blood against different variants of the MSP1 protein, as well as using in vitro tests to see whether antibodies from vaccinated individuals could prevent malaria parasites from growing in lab culture. What the trial shows: The safety outcomes of the trial showed that the most common type of side effect experienced by the volunteers was pain at the injection site. The vast majority of such events were graded as mild, although there was one single case of a severe event (high levels of pain experienced by one volunteer at the injection site). There was no significant association between the chance of side effects and the vaccine dosage that an individual received. Following vaccination, antibody levels against the protein on which the vaccine was based were detected, although these levels dropped over time. The researchers did not see a strong association between the vaccine dosage that individuals received and the level of antibody response. However, the two vaccines when compared seemed to be equally good at raising an immune response and both caused antibodies to be raised corresponding to different variants of the MSP1 protein. However, the antibodies raised did not seem to be particularly effective at preventing malaria parasites from growing in lab culture. Strengths and limitations: Strengths of this study include a comparison of three different dosage levels of the vaccines under study, as well as a comparison of two vaccines based on the same protein, representing different parasite lines. Limitations to the study include the small number of participants, which makes the trial underpowered to detect all but large differences in side effects between the groups being compared. A placebo arm was not included in the trial, so it is not possible to be sure that the numbers of side effects observed here can be attributed to the vaccines or not. Finally, the procedure for assigning individuals to the two different vaccines involved alternation, rather than true randomization, which could have minimized the risk of bias. Contribution to the evidence: The trial reported here is an essential step in vaccine development. The results provide the first evidence relating to safety for these two vaccines, and do not raise any safety concerns at this stage. Although the vaccines raised an immune response, the antibodies raised did not seem to have much of an effect on malaria parasites in vitro. While these vaccines are safe, alternative MSP1 vaccine formulations anticipated to bring about a greater immune response will likely be studied before proceeding to field studies.
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Affiliation(s)
- Elissa Malkin
- Malaria Vaccine Development Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, United States of America
| | - Carole A Long
- Malaria Vaccine Development Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, United States of America
| | - Anthony W Stowers
- Malaria Vaccine Development Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, United States of America
| | - Lanling Zou
- Malaria Vaccine Development Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, United States of America
| | - Sanjay Singh
- Malaria Vaccine Development Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, United States of America
| | - Nicholas J MacDonald
- Malaria Vaccine Development Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, United States of America
| | - David L Narum
- Malaria Vaccine Development Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, United States of America
| | - Aaron P Miles
- Malaria Vaccine Development Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, United States of America
| | - Andrew C Orcutt
- Malaria Vaccine Development Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, United States of America
| | - Olga Muratova
- Malaria Vaccine Development Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, United States of America
| | - Samuel E Moretz
- Malaria Vaccine Development Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, United States of America
| | - Hong Zhou
- Malaria Vaccine Development Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, United States of America
| | - Ababacar Diouf
- Malaria Vaccine Development Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, United States of America
| | - Michael Fay
- Biostatistics Research Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Eveline Tierney
- PATH Malaria Vaccine Initiative, Bethesda, Maryland, United States of America
| | - Philip Leese
- Quintiles Phase 1 Services, Lenexa, Kansas, United States of America
| | - Siddhartha Mahanty
- Malaria Vaccine Development Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, United States of America
| | - Louis H Miller
- Malaria Vaccine Development Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, United States of America
| | - Allan Saul
- Malaria Vaccine Development Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, United States of America
| | - Laura B Martin
- Malaria Vaccine Development Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, United States of America
- * To whom correspondence should be addressed. E-mail:
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Wille-Reece U, Flynn BJ, Loré K, Koup RA, Miles AP, Saul A, Kedl RM, Mattapallil JJ, Weiss WR, Roederer M, Seder RA. Toll-like receptor agonists influence the magnitude and quality of memory T cell responses after prime-boost immunization in nonhuman primates. ACTA ACUST UNITED AC 2006; 203:1249-58. [PMID: 16636134 PMCID: PMC2121207 DOI: 10.1084/jem.20052433] [Citation(s) in RCA: 225] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
There is a remarkable heterogeneity in the functional profile (quality) of T cell responses. Importantly, the magnitude and/or quality of a response required for protection may be different depending on the infection. Here, we assessed the capacity of different Toll like receptor (TLR)-binding compounds to influence T helper cell (Th)1 and CD8+ T cell responses when used as adjuvants in nonhuman primates (NHP) with HIV Gag as a model antigen. NHP were immunized with HIV Gag protein emulsified in Montanide ISA 51, an oil-based adjuvant, with or without a TLR7/8 agonist, a TLR8 agonist, or the TLR9 ligand cytosine phosphate guanosine oligodeoxynucleotides (CpG ODN), and boosted 12 wk later with a replication-defective adenovirus-expressing HIV-Gag (rAD-Gag). Animals vaccinated with HIV Gag protein/Montanide and CpG ODN or the TLR7/8 agonist had higher frequencies of Th1 responses after primary immunization compared to all other vaccine groups. Although the rAD-Gag boost did not elevate the frequency of Th1 memory cytokine responses, there was a striking increase in HIV Gag-specific CD8+ T cell responses after the boost in all animals that had received a primary immunization with any of the TLR adjuvants. Importantly, the presence and type of TLR adjuvant used during primary immunization conferred stability and dramatically influenced the magnitude and quality of the Th1 and CD8+ T cell responses after the rAD-Gag boost. These data provide insights for designing prime-boost immunization regimens to optimize Th1 and CD8+ T cell responses.
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Affiliation(s)
- Ulrike Wille-Reece
- Cellular Immunology Section, Vaccine Research Center, National Institutes of Health, Bethesda, MD 20892, USA
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Miles AP, Saul A. Quantifying recombinant proteins and their degradation products using SDS-PAGE and scanning laser densitometry. Methods Mol Biol 2005; 308:349-56. [PMID: 16082047 DOI: 10.1385/1-59259-922-2:349] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Affiliation(s)
- Aaron P Miles
- Biochemical Assay Development and Quality Control, Malaria Vaccine Development Branch, National Institute of Allergy and Infectious Diseases, Rockville, MD, USA
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Zhu D, Saul AJ, Miles AP. A quantitative slot blot assay for host cell protein impurities in recombinant proteins expressed in E. coli. J Immunol Methods 2005; 306:40-50. [PMID: 16137696 DOI: 10.1016/j.jim.2005.07.021] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2004] [Revised: 07/14/2005] [Accepted: 07/20/2005] [Indexed: 11/22/2022]
Abstract
Residual host cell protein impurities in recombinant proteins intended for human use must be accurately quantified to help establish their safety. We describe a novel means of host cell protein quantitation, in which a slot blot system was employed together with scanning laser densitometry to allow picogram level sensitivity in detection of residual host cell proteins in unpurified fermentation products and final purified bulk samples. Two allelic forms of merozoite surface protein 1, a promising malaria vaccine candidate antigen currently undergoing evaluation in clinical trials, were expressed in E. coli as clinical grade proteins, refolded, and carried through several chromatographic purification steps. Several lots of these proteins were analyzed with this generic quantitative assay that uses rat polyclonal antibodies generated against soluble and insoluble E. coli proteins. The assay had a detection range of 6.1-1562 ng/mL, with a detection limit of 6.1 ng/mL, comparable to reported ELISA-based methods. This assay proved simple yet very sensitive and accurate, giving highly reproducible results. Thus it is suitable for evaluating host cell protein levels in clinical grade recombinant proteins expressed in E. coli.
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Affiliation(s)
- Daming Zhu
- Malaria Vaccine Development Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20852, USA.
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Miles AP, Zhu D, Saul A. Determining residual host cell antigen levels in purified recombinant proteins by slot blot and scanning laser densitometry. Methods Mol Biol 2005; 308:233-42. [PMID: 16082039 DOI: 10.1385/1-59259-922-2:233] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Affiliation(s)
- Aaron P Miles
- Biochemical Assay Development and Quality Control, Malaria Vaccine Development Branch, National Institute of Allergy and Infectious Diseases, Rockville, MD, USA
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10
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Malkin EM, Diemert DJ, McArthur JH, Perreault JR, Miles AP, Giersing BK, Mullen GE, Orcutt A, Muratova O, Awkal M, Zhou H, Wang J, Stowers A, Long CA, Mahanty S, Miller LH, Saul A, Durbin AP. Phase 1 clinical trial of apical membrane antigen 1: an asexual blood-stage vaccine for Plasmodium falciparum malaria. Infect Immun 2005; 73:3677-85. [PMID: 15908397 PMCID: PMC1111886 DOI: 10.1128/iai.73.6.3677-3685.2005] [Citation(s) in RCA: 207] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Apical membrane antigen 1 (AMA1), a polymorphic merozoite surface protein, is a leading blood-stage malaria vaccine candidate. A phase 1 trial was conducted with 30 malaria-naive volunteers to assess the safety and immunogenicity of the AMA1-C1 malaria vaccine. AMA1-C1 contains an equal mixture of recombinant proteins based on sequences from the FVO and 3D7 clones of Plasmodium falciparum. The proteins were expressed in Pichia pastoris and adsorbed on Alhydrogel. Ten volunteers in each of three dose groups (5 mug, 20 mug, and 80 mug) were vaccinated in an open-label study at 0, 28, and 180 days. The vaccine was well tolerated, with pain at the injection site being the most commonly observed reaction. Anti-AMA1 immunoglobulin G (IgG) was detected by enzyme-linked immunosorbent assay (ELISA) in 15/28 (54%) volunteers after the second immunization and in 23/25 (92%) after the third immunization, with equal reactivity to both AMA1-FVO and AMA1-3D7 vaccine components. A significant dose-response relationship between antigen dose and antibody response by ELISA was observed, and the antibodies were predominantly of the IgG1 isotype. Confocal microscopic evaluation of sera from vaccinated volunteers demonstrated reactivity with P. falciparum schizonts in a pattern similar to native parasite AMA1. Antigen-specific in vitro inhibition of both FVO and 3D7 parasites was achieved with IgG purified from sera of vaccinees, demonstrating biological activity of the antibodies. To our knowledge, this is the first AMA1 vaccine candidate to elicit functional immune responses in malaria-naive humans, and our results support the further development of this vaccine.
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Affiliation(s)
- Elissa M Malkin
- Johns Hopkins University Bloomberg School of Public Health, Center for Immunization Research, 624 N. Broadway, Room 217, Baltimore, MD 21205, USA.
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Malkin EM, Durbin AP, Diemert DJ, Sattabongkot J, Wu Y, Miura K, Long CA, Lambert L, Miles AP, Wang J, Stowers A, Miller LH, Saul A. Phase 1 vaccine trial of Pvs25H: a transmission blocking vaccine for Plasmodium vivax malaria. Vaccine 2005; 23:3131-8. [PMID: 15837212 PMCID: PMC10994215 DOI: 10.1016/j.vaccine.2004.12.019] [Citation(s) in RCA: 172] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2004] [Revised: 12/20/2004] [Accepted: 12/28/2004] [Indexed: 11/19/2022]
Abstract
Plasmodium vivax is responsible for the majority of malaria cases outside of Africa, and results in substantial morbidity. Transmission blocking vaccines are a potentially powerful component of a multi-faceted public health approach to controlling or eliminating malaria. We report the first phase 1 clinical trial of a P. vivax transmission blocking vaccine in humans. The Pvs25H vaccine is a recombinant protein derived from the Pvs25 surface antigen of P. vivax ookinetes. The protein was expressed in Saccharomyces cerevisiae, purified, and adsorbed onto Alhydrogel. Ten volunteers in each of three dose groups (5, 20, or 80 microg) were vaccinated by intramuscular injection in an open-label study at 0, 28 and 180 days. No vaccine-related serious adverse events were observed. The majority of adverse events causally related to vaccination were mild or moderate in severity. Injection site tenderness was the most commonly observed adverse event. Anti-Pvs25H antibody levels measured by ELISA peaked after the third vaccination. Vaccine-induced antibody is functionally active as evidenced by significant transmission blocking activity in the membrane feeding assay. Correlation between antibody concentration and degree of inhibition was observed. Pvs25H generates transmission blocking immunity in humans against P. vivax demonstrating the potential of this antigen as a component of a transmission blocking vaccine.
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Affiliation(s)
- Elissa M Malkin
- Malaria Vaccine Development Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 5640 Fishers Lane, Twinbrook 1, Room 1123, Rockville, MD 20852, USA.
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Miles AP, McClellan HA, Rausch KM, Zhu D, Whitmore MD, Singh S, Martin LB, Wu Y, Giersing BK, Stowers AW, Long CA, Saul A. Montanide® ISA 720 vaccines: quality control of emulsions, stability of formulated antigens, and comparative immunogenicity of vaccine formulations. Vaccine 2005; 23:2530-9. [PMID: 15752840 DOI: 10.1016/j.vaccine.2004.08.049] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2004] [Revised: 08/27/2004] [Accepted: 08/30/2004] [Indexed: 11/24/2022]
Abstract
Montanide ISA 720 is an experimental adjuvant, formulated as water-in-oil emulsions, that induces high antibody titers in several animal species. It has been used in human vaccine trials with malaria and HIV vaccines. The heightened response is likely due, in part, to the formation of a depot at the injection site. However, post-formulation modifications were seen with seven proteins tested during storage of ISA 720 formulations at 37 degrees C for 1 week and two proteins stored longer at 4 degrees C. Potency studies in mice, in which the stored vaccines were diluted into placebo emulsions for appropriate dosing, indicated that this instability could lead to loss of immunogenicity in the post-injection depot, limiting the allowable storage time of preformed vaccines. We describe point-of-injection formulation for ISA 720 vaccines that meets the requirement for in vitro stability. For preformed vaccines, addition of glycine or glycylglycine prevented antigen modification on storage at 37 degrees C, providing a potential way of stabilizing antigen/ISA 720 formulations for in vitro storage and the post-injection depot.
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Affiliation(s)
- Aaron P Miles
- Malaria Vaccine Development Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 5640 Fishers Lane, Twinbrook I Room 1118, Rockville, MD 20852, USA.
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Affiliation(s)
- Aaron P Miles
- Biochemical Assay Development and Quality Control, Malaria Vaccine Development Branch, National Institute of Allergy and Infectious Diseases, Rockville, MD, USA
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Abstract
In previously published studies, Saccharomyces cerevisiae recombinant protein expression systems have been employed to express the malaria parasite antigen Pfs25, a candidate transmission-blocking vaccine antigen against Plasmodium falciparum malaria. However, despite having been in two Phase 1 trials, the recombinant Pfs25 so produced (previously called TBV25H) exists as a mixture of two monomeric protein conformational forms, Pfs25H-A and Pfs25H-B. In this study, we optimized the expression and purification of the two Pfs25H conformers in S. cerevisiae, and characterized their biochemical and antigenic properties, immunogenicities, and transmission-blocking activities. Pfs25H-A is apparently homogeneous, and has the correct conformation as measured by monoclonal antibody recognition. It is, however, expressed at a low yield of only 0.19mg/l. By contrast, Pfs25H-B is produced as a heterogeneous population of molecules that do not seem to have the correct conformation. Nonetheless, both forms appear equally effective in their ability to produce transmission-blocking antibodies in mice. To address the low yield seen with S. cerevisiae, we also expressed Pfs25 in Pichia pastoris. P. pastoris is apparently superior to S. cerevisiae in producing higher yield, immunologically more potent, biologically more active Pfs25H-A.
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Affiliation(s)
- Lanling Zou
- Malaria Vaccine Development Unit, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20852, USA
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Kennedy MC, Wang J, Zhang Y, Miles AP, Chitsaz F, Saul A, Long CA, Miller LH, Stowers AW. In vitro studies with recombinant Plasmodium falciparum apical membrane antigen 1 (AMA1): production and activity of an AMA1 vaccine and generation of a multiallelic response. Infect Immun 2002; 70:6948-60. [PMID: 12438374 PMCID: PMC133034 DOI: 10.1128/iai.70.12.6948-6960.2002] [Citation(s) in RCA: 209] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Apical membrane antigen 1 (AMA1) is regarded as a leading malaria blood-stage vaccine candidate. While the overall structure of AMA1 is conserved in Plasmodium spp., numerous AMA1 allelic variants of P. falciparum have been described. The effect of AMA1 allelic diversity on the ability of a recombinant AMA1 vaccine to protect against human infection by different P. falciparum strains is unknown. We characterize two allelic forms of AMA1 that were both produced in Pichia pastoris at a sufficient economy of scale to be usable for clinical vaccine studies. Both proteins were used to immunize rabbits, singly and in combination, in order to evaluate their immunogenicity and the ability of elicited antibodies to block the growth of different P. falciparum clones. Both antigens, when used alone, elicited high homologous anti-AMA1 titers, with reduced strain cross-reactivity. Similarly, sera from rabbits immunized with a single antigen were capable of blocking the growth of homologous parasite strains at levels theoretically sufficient to clear parasite infections. However, heterologous inhibition was significantly reduced, providing experimental evidence that AMA1 allelic diversity is a result of immune pressure. Encouragingly, rabbits immunized with a combination of both antigens exhibited titers and levels of parasite inhibition as good as those of the single-antigen-immunized rabbits for each of the homologous parasite lines, and consequently exhibited a broadening of allelic diversity coverage.
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Affiliation(s)
- Michael C Kennedy
- Malaria Vaccine Development Unit, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland 20852, USA
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Miles AP, Zhang Y, Saul A, Stowers AW. Large-scale purification and characterization of malaria vaccine candidate antigen Pvs25H for use in clinical trials. Protein Expr Purif 2002; 25:87-96. [PMID: 12071703 DOI: 10.1006/prep.2001.1613] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The budding yeast Saccharomyces cerevisiae has been used to express the recombinant protein Pvs25H, currently the only candidate transmission-blocking vaccine against Plasmodium vivax malaria. This molecule contains four epidermal growth factor-like domains and is expressed as at least two stable monomeric forms with different physicochemical properties. Pvs25H-A is apparently homogeneous and seems to have a correct disulfide bond structure. By contrast, Pvs25H-B is produced as a heterogeneous population of molecules, some of which are associated with an as yet unidentified chromophore, and it contains both internal and N-terminal cleavages. We report here a procedure for successfully separating these two forms with a process suitable for clinical production of this antigen.
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Affiliation(s)
- Aaron P Miles
- Malaria Vaccine Development Unit, National Institute of Allergy and Infectious Diseases, Rockville, Maryland 20852, USA
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Brady CP, Shimp RL, Miles AP, Whitmore M, Stowers AW. High-level production and purification of P30P2MSP1(19), an important vaccine antigen for malaria, expressed in the methylotropic yeast Pichia pastoris. Protein Expr Purif 2001; 23:468-75. [PMID: 11722185 DOI: 10.1006/prep.2001.1526] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
P30P2MSP1(19) is a recombinant subunit vaccine derived from merozoite surface protein 1 (MSP1) of Plasmodium falciparum, the causative agent of malaria. P30P2MSP1(19) consists of two universal T-cell epitopes fused to the most C-terminal 19-kDa portion of MSP1, and this protein has previously shown promising potential as a vaccine for malaria. However, previous attempts at producing this molecule in Saccharomyces cerevisiae resulted in the production of a truncated form of the molecule missing most of the universal T-cell epitopes. Here, we report the production of full-length P30P2MSP1(19) in Pichia pastoris. As salt precipitation is a common problem during P. pastoris high-density fermentation, we utilized an alternative low-salt, fully defined medium that did not reduce growth rates or biomass yields to avoid precipitation. A total of 500 mg/L of secreted purified protein was produced in high cell density fermentation and the protein was purified in one step utilizing nickel-chelate chromatography. P30P2MSP1(19) produced in Pichia was reactive with monoclonal antibodies that recognize only conformational epitopes on correctly folded MSP1. Rabbits immunized with this molecule generated higher and more uniform antibody titers than rabbits immunized with the protein produced in Saccharomyces. P30P2MSP1(19) produced in Pichia may prove to be a more efficacious vaccine than that produced in Saccharomyces and Pichia would provide a system for the cost-effective production of such a vaccine.
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Affiliation(s)
- C P Brady
- Malaria Vaccine Development Unit, Laboratory of Parasitic Diseases, Rockville, Maryland 20852, USA
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Abstract
Effective 1992, the US Congress implemented the Resource-Based Relative Value Scale (RBRVS) for pricing and reimbursing Medicare physician services. This study evaluates the post-1991 impacts of RBRVS on the utilization volumes of two leading cardiovascular procedures--Percutaneous Transluminal Coronary Artery (PTCA) and Coronary Artery Bypass Grafts (CABG). The regression model results based on HCFA-supplied data suggest that the new reimbursement policy reduced (increased) utilization volumes of the more (less) expensive CABG (PTCA) procedures. Physician adjustments to tightened HCFA reimbursements are partly aided by the increased percentage of Medicare patients enrolled in Medigap. The RBRVS fee schedule appears to be meeting its intended cost containment policy goals for the leading cardiovascular procedures.
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Affiliation(s)
- A A Okunade
- Department of Economics, University of Memphis, TN 38152, USA.
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