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Hillier CJ, Ware LA, Barbosa A, Angov E, Lyon JA, Heppner DG, Lanar DE. Process development and analysis of liver-stage antigen 1, a preerythrocyte-stage protein-based vaccine for Plasmodium falciparum. Infect Immun 2005; 73:2109-15. [PMID: 15784552 PMCID: PMC1087442 DOI: 10.1128/iai.73.4.2109-2115.2005] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Plasmodium falciparum liver-stage antigen 1 (LSA-1) is expressed solely in infected hepatocytes and is thought to have a role in liver schizogony and merozoite release. Specific humoral, cellular, and cytokine immune responses to LSA-1 are well documented, with epitopes identified that correlate with antibody production, proliferative T-cell responses, or cytokine induction. With the goal of developing a vaccine against this preerythrocyte-stage protein, we undertook the good manufacturing practices (GMP) manufacture of a recombinant LSA-1 construct, LSA-NRC, incorporating the N- and C-terminal regions of the protein and two of the centrally placed 17-amino-acid repeats. To improve the protein yield, a method of codon harmonization was employed to reengineer the gene sequence for expression in Escherichia coli. A 300-liter GMP fermentation produced 8 kg of bacterial cell paste, and a three-step column chromatographic method yielded 8 mg of purified antigen per g of paste. The final bulk protein was >98% pure, demonstrated long-term stability, and contained <0.005 endotoxin units per 50 microg of protein. To accomplish the initial stages of evaluation of this protein as a human-use vaccine against malaria, we immunized rabbits and mice with LSA-NRC in Montanide ISA 720. New Zealand White rabbits and A/J (H-2K) mice produced high-titer antibodies that recognized liver-stage parasites in infected cultured human hepatocytes. Gamma interferon-producing cells, which have been associated with LSA-1-mediated protection, were detected in splenocytes harvested from immunized mice. Finally, sera taken from people living in a region where malaria is holoendemic recognized LSA-NRC by Western blotting.
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52
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Pichyangkul S, Gettayacamin M, Miller RS, Lyon JA, Angov E, Tongtawe P, Ruble DL, Heppner DG, Kester KE, Ballou WR, Diggs CL, Voss G, Cohen JD, Walsh DS. Pre-clinical evaluation of the malaria vaccine candidate P. falciparum MSP1(42) formulated with novel adjuvants or with alum. Vaccine 2005; 22:3831-40. [PMID: 15364429 DOI: 10.1016/j.vaccine.2004.07.023] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2003] [Revised: 03/19/2004] [Accepted: 07/14/2004] [Indexed: 10/26/2022]
Abstract
We compared the safety and immunogenicity of the recombinant Plasmodium falciparum MSP1(42) antigen formulated with four novel adjuvant systems (AS01B, AS02A, AS05 and AS08) to alum in rhesus monkeys. All five formulations of MSP1(42) were safe and immunogenic. Whereas, all MSP1(42) formulations tested generated high stimulation indices for lymphocyte proliferation (ranging from 27 to 50), the AS02A and AS01B formulations induced the highest levels of specific anti-MSP1(42) antibody. ELISPOT assays showed that the AS02A and AS01B vaccine formulations-induced different cytokine response profiles. Using the ratio of IFN-gamma/IL-5 secreting cells as the metric, the AS01B formulation induced a strong Th1 response, whereas the AS02A formulation induced a balanced Th1/Th2 response. The IFN-gamma response generated by AS02A and AS01B formulations persisted at least 24 weeks after final vaccination. The notable difference in Th1/Th2 polarization induced by the AS02A and AS01B formulations warrants comparative clinical testing.
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Heppner DG, Kester KE, Ockenhouse CF, Tornieporth N, Ofori O, Lyon JA, Stewart VA, Dubois P, Lanar DE, Krzych U, Moris P, Angov E, Cummings JF, Leach A, Hall BT, Dutta S, Schwenk R, Hillier C, Barbosa A, Ware LA, Nair L, Darko CA, Withers MR, Ogutu B, Polhemus ME, Fukuda M, Pichyangkul S, Gettyacamin M, Diggs C, Soisson L, Milman J, Dubois MC, Garçon N, Tucker K, Wittes J, Plowe CV, Thera MA, Duombo OK, Pau MG, Goudsmit J, Ballou WR, Cohen J. Towards an RTS,S-based, multi-stage, multi-antigen vaccine against falciparum malaria: progress at the Walter Reed Army Institute of Research. Vaccine 2005; 23:2243-50. [PMID: 15755604 DOI: 10.1016/j.vaccine.2005.01.142] [Citation(s) in RCA: 134] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
The goal of the Malaria Vaccine Program at the Walter Reed Army Institute of Research (WRAIR) is to develop a licensed multi-antigen, multi-stage vaccine against Plasmodium falciparum able to prevent all symptomatic manifestations of malaria by preventing parasitemia. A secondary goal is to limit disease in vaccinees that do develop malaria. Malaria prevention will be achieved by inducing humoral and cellular immunity against the pre-erythrocytic circumsporozoite protein (CSP) and the liver stage antigen-1 (LSA-1). The strategy to limit disease will target immune responses against one or more blood stage antigens, merozoite surface protein-1 (MSP-1) and apical merozoite antigen-1 (AMA-1). The induction of T- and B-cell memory to achieve a sustained vaccine response may additionally require immunization with an adenovirus vector such as adenovirus serotype 35. RTS,S, a CSP-derived antigen developed by GlaxoSmithKline Biologicals in collaboration with the Walter Reed Army Institute of Research over the past 17 years, is the cornerstone of our program. RTS,S formulated in AS02A (a GSK proprietary formulation) is the only vaccine candidate shown in field trials to prevent malaria and, in one instance, to limit disease severity. Our vaccine development plan requires proof of an individual antigen's efficacy in a Phase 2 laboratory challenge or field trial prior to its integration into an RTS,S-based, multi-antigen vaccine. Progress has been accelerated through extensive partnerships with industrial, academic, governmental, and non-governmental organizations. Recent safety, immunogenicity, and efficacy trials in the US and Africa are presented, as well as plans for the development of a multi-antigen vaccine.
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Walsh DS, Wilairatana P, Tang DB, Heppner DG, Brewer TG, Krudsood S, Silachamroon U, Phumratanaprapin W, Siriyanonda D, Looareesuwan S. Randomized Trial of 3-Dose Regimens of Tafenoquine (WR238605) versus Low-Dose Primaquine for Preventing Plasmodium vivax Malaria Relapse. Clin Infect Dis 2004; 39:1095-103. [PMID: 15486831 DOI: 10.1086/424508] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2004] [Accepted: 03/07/2004] [Indexed: 11/03/2022] Open
Abstract
BACKGROUND Tafenoquine is an 8-aminoquinoline developed as a more effective replacement for primaquine. In a previous dose-ranging study in Thailand, 3 tafenoquine regimens with total doses ranging from 500 mg to 3000 mg prevented relapse of Plasmodium vivax malaria in most patients when administered 2 days after receipt of a blood schizonticidal dose of chloroquine. METHODS To improve convenience and to begin comparison of tafenoquine with primaquine, 80 patients with P. vivax infection were randomized to receive 1 of the following 5 treatments 1 day after receiving a blood schizonticidal dose of chloroquine: (A) tafenoquine, 300 mg per day for 7 days (n=18); (B) tafenoquine, 600 mg per day for 3 days (n=19); (C) tafenoquine, 600 mg as a single dose (n=18); (D) no further treatment (n=13); or (E) primaquine base, 15 mg per day for 14 days (n=12). The minimum duration of protocol follow-up was 8 weeks, with additional follow-up to 24 weeks. RESULTS Forty-six of 55 tafenoquine recipients, 10 of 13 recipients of chloroquine only, and 12 of 12 recipients of chloroquine plus primaquine completed at least 8 weeks of follow-up (or had relapse). There was 1 relapse among recipients of chloroquine plus tafenoquine, 8 among recipients of chloroquine only, and 3 among recipients of chloroquine plus primaquine. The rate of protective efficacy (determined on the basis of reduction in incidence density) for all recipients of chloroquine plus tafenoquine, compared with recipients of chloroquine plus primaquine, was 92.6% (95% confidence interval, 7.3%-99.9%; P=.042, by Fisher's exact test). CONCLUSIONS Tafenoquine doses as low as a single 600-mg dose may be useful for prevention of relapse of P. vivax malaria in Thailand.
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55
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Ballou WR, Arevalo-Herrera M, Carucci D, Richie TL, Corradin G, Diggs C, Druilhe P, Giersing BK, Saul A, Heppner DG, Kester KE, Lanar DE, Lyon J, Hill AVS, Pan W, Cohen JD. Update on the clinical development of candidate malaria vaccines. Am J Trop Med Hyg 2004; 71:239-47. [PMID: 15331843] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/30/2023] Open
Abstract
The recent availability of significantly increased levels of funding for unmet medical needs in the developing world, made available by newly created public-private-partnerships, has proven to be a powerful driver for stimulating clinical development of candidate vaccines for malaria. This new way forward promises to greatly increase the likelihood of bringing a safe and effective vaccine to licensure. The investigators bring together important published and unpublished information that illuminates the status of malaria vaccine development. They focus their comments on those candidate vaccines that are currently in or expected to enter clinical trials in the next 12 months.
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56
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Walsh DS, Pichyangkul S, Gettayacamin M, Tongtawe P, Siegrist CA, Hansukjariya P, Kester KE, Holland CA, Voss G, Cohen J, Stewart AV, Miller RS, Ballou WR, Heppner DG. Safety and immunogenicity of rts,s+trap malaria vaccine, formulated in the as02a adjuvant system, in infant rhesus monkeys. Am J Trop Med Hyg 2004; 70:499-509. [PMID: 15155981] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/29/2023] Open
Abstract
Malaria vaccine RTS,S combined with thrombospondin-related anonymous protein (TRAP) and formulated with AS02A (RTS,S+TRAP/AS02A) is safe and immunogenic in adult humans and rhesus monkeys (Macaca mulatta). Here, RTS,S+TRAP/AS02A was administered on a 0-, 1-, and 3-month schedule to three cohorts of infant monkeys, along with adult comparators. Cohort 1 evaluated 1/5, 1/2, and full adult doses, with the first dose administration at one month of age; cohort 2 monkeys received full adult doses, with the first dose administration at one versus three months of age; and, cohort 3 compared infants gestated in mothers with or without previous RTS,S/AS02A immunization. Immunization site reactogenicity was mild. Some infants, including the phosphate-buffered saline only recipient, developed transient iron-deficiency anemia, which is considered a result of repeated phlebotomies. All RTS,S+TRAP/AS02A regimens induced vigorous antibody responses that persisted through 12 weeks after the last vaccine dose. Modest lymphoproliferative and ELISPOT (interferon-gamma and interleukin-5) responses, particularly to TRAP, approximated adult comparators. RTS,S+TRAP/AS02A was safe and well tolerated. Vigorous antibody production and modest, selective cell-mediated immune responses suggest that RTS,S+TRAP/AS02A may be immunogenic in human infants.
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57
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Wang R, Epstein J, Charoenvit Y, Baraceros FM, Rahardjo N, Gay T, Banania JG, Chattopadhyay R, de la Vega P, Richie TL, Tornieporth N, Doolan DL, Kester KE, Heppner DG, Norman J, Carucci DJ, Cohen JD, Hoffman SL. Induction in Humans of CD8+ and CD4+ T Cell and Antibody Responses by Sequential Immunization with Malaria DNA and Recombinant Protein. THE JOURNAL OF IMMUNOLOGY 2004; 172:5561-9. [PMID: 15100299 DOI: 10.4049/jimmunol.172.9.5561] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Vaccine-induced protection against diseases like malaria, AIDS, and cancer may require induction of Ag-specific CD8(+) and CD4(+) T cell and Ab responses in the same individual. In humans, a recombinant Plasmodium falciparum circumsporozoite protein (PfCSP) candidate vaccine, RTS,S/adjuvant system number 2A (AS02A), induces T cells and Abs, but no measurable CD8(+) T cells by CTL or short-term (ex vivo) IFN-gamma ELISPOT assays, and partial short-term protection. P. falciparum DNA vaccines elicit CD8(+) T cells by these assays, but no protection. We report that sequential immunization with a PfCSP DNA vaccine and RTS,S/AS02A induced PfCSP-specific Abs and Th1 CD4(+) T cells, and CD8(+) cytotoxic and Tc1 T cells. Depending upon the immunization regime, CD4(+) T cells were involved in both the induction and production phases of PfCSP-specific IFN-gamma responses, whereas, CD8(+) T cells were involved only in the production phase. IFN-gamma mRNA up-regulation was detected in both CD45RA(-) (CD45RO(+)) and CD45RA(+)CD4(+) and CD8(+) T cell populations after stimulation with PfCSP peptides. This finding suggests CD45RA(+) cells function as effector T cells. The induction in humans of the three primary Ag-specific adaptive immune responses establishes a strategy for developing immunization regimens against diseases in desperate need of vaccines.
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MESH Headings
- Amino Acid Sequence
- Animals
- Antibodies, Protozoan/biosynthesis
- CD4-Positive T-Lymphocytes/immunology
- CD4-Positive T-Lymphocytes/metabolism
- CD8-Positive T-Lymphocytes/immunology
- CD8-Positive T-Lymphocytes/metabolism
- Cytotoxicity Tests, Immunologic
- Epitopes, T-Lymphocyte/administration & dosage
- Epitopes, T-Lymphocyte/immunology
- Hepatitis B Antibodies/biosynthesis
- Hepatitis B Surface Antigens/immunology
- Humans
- Immunization Schedule
- Immunization, Secondary/methods
- Interferon-gamma/biosynthesis
- Malaria Vaccines/administration & dosage
- Malaria Vaccines/genetics
- Malaria Vaccines/immunology
- Malaria, Falciparum/immunology
- Malaria, Falciparum/prevention & control
- Molecular Sequence Data
- Plasmodium falciparum/immunology
- Protozoan Proteins/administration & dosage
- Protozoan Proteins/genetics
- Protozoan Proteins/immunology
- T-Lymphocyte Subsets
- T-Lymphocytes, Cytotoxic/immunology
- T-Lymphocytes, Cytotoxic/metabolism
- Th1 Cells/immunology
- Th1 Cells/metabolism
- Vaccines, DNA/administration & dosage
- Vaccines, DNA/genetics
- Vaccines, DNA/immunology
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58
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Pichyangkul S, Yongvanitchit K, Kum-arb U, Hemmi H, Akira S, Krieg AM, Heppner DG, Stewart VA, Hasegawa H, Looareesuwan S, Shanks GD, Miller RS. Malaria Blood Stage Parasites Activate Human Plasmacytoid Dendritic Cells and Murine Dendritic Cells through a Toll-Like Receptor 9-Dependent Pathway. THE JOURNAL OF IMMUNOLOGY 2004; 172:4926-33. [PMID: 15067072 DOI: 10.4049/jimmunol.172.8.4926] [Citation(s) in RCA: 208] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
A common feature of severe Plasmodium falciparum infection is the increased systemic release of proinflammatory cytokines that contributes to the pathogenesis of malaria. Using human blood, we found that blood stage schizonts or soluble schizont extracts activated plasmacytoid dendritic cells (PDCs) to up-regulate CD86 expression and produce IFN-alpha. IFN-alpha production was also detected in malaria-infected patients, but the levels of circulating PDCs were markedly reduced, possibly because of schizont-stimulated up-regulation of CCR7, which is critical for PDC migration. The schizont-stimulated PDCs elicited a poor T cell response, but promoted gamma delta T cell proliferation and IFN-gamma production. The schizont immune stimulatory effects could be reproduced using murine DCs and required the Toll-like receptor 9 (TLR9)-MyD88 signaling pathway. Although the only known TLR9 ligand is CpG motifs in pathogen DNA, the activity of the soluble schizont extract was far greater than that of schizont DNA, and it was heat labile and precipitable with ammonium sulfate, unlike the activity of bacterial DNA. These results demonstrate that schizont extracts contain a novel and previously unknown ligand for TLR9 and suggest that the stimulatory effects of this ligand on PDCs may play a key role in immunoregulation and immunopathogenesis of human falciparum malaria.
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MESH Headings
- Adaptor Proteins, Signal Transducing
- Animals
- Antigens, Differentiation/genetics
- Antigens, Differentiation/physiology
- Cell Fractionation
- Cell Movement/immunology
- Cells, Cultured
- Coculture Techniques
- DNA-Binding Proteins/deficiency
- DNA-Binding Proteins/genetics
- DNA-Binding Proteins/physiology
- Dendritic Cells/immunology
- Dendritic Cells/metabolism
- Dendritic Cells/parasitology
- Dendritic Cells/pathology
- Humans
- Immunity, Cellular
- Interferon-alpha/biosynthesis
- Interferon-alpha/blood
- Malaria, Falciparum/blood
- Malaria, Falciparum/immunology
- Malaria, Falciparum/parasitology
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Myeloid Differentiation Factor 88
- Plasmodium falciparum/chemistry
- Plasmodium falciparum/growth & development
- Plasmodium falciparum/immunology
- Receptors, Antigen, T-Cell, gamma-delta/biosynthesis
- Receptors, Cell Surface/deficiency
- Receptors, Cell Surface/genetics
- Receptors, Cell Surface/physiology
- Receptors, Immunologic/deficiency
- Receptors, Immunologic/genetics
- Receptors, Immunologic/physiology
- Signal Transduction/genetics
- Signal Transduction/immunology
- Solubility
- T-Lymphocyte Subsets/immunology
- T-Lymphocyte Subsets/metabolism
- T-Lymphocyte Subsets/parasitology
- Toll-Like Receptor 9
- Up-Regulation/immunology
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59
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Epstein JE, Charoenvit Y, Kester KE, Wang R, Newcomer R, Fitzpatrick S, Richie TL, Tornieporth N, Heppner DG, Ockenhouse C, Majam V, Holland C, Abot E, Ganeshan H, Berzins M, Jones T, Freydberg CN, Ng J, Norman J, Carucci DJ, Cohen J, Hoffman SL. Safety, tolerability, and antibody responses in humans after sequential immunization with a PfCSP DNA vaccine followed by the recombinant protein vaccine RTS,S/AS02A. Vaccine 2004; 22:1592-603. [PMID: 15068840 DOI: 10.1016/j.vaccine.2004.01.031] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Optimal protection against malaria may require induction of high levels of protective antibody and CD8(+) and CD4(+) T cell responses. In humans, malaria DNA vaccines elicit CD8(+) cytotoxic T cells (CTL) and IFNgamma responses as measured by short-term (ex vivo) ELISPOT assays, and recombinant proteins elicit antibodies and excellent T cell responses, but no CD8(+) CTL or CD8(+) IFNgamma-producing cells as measured by ex vivo ELISPOT. Priming with DNA and boosting with recombinant pox virus elicits much better T cell responses than DNA alone, but not antibody responses. In an attempt to elicit antibodies and enhanced T cell responses, we administered RTS,S/AS02A, a partially protective Plasmodium falciparum recombinant circumsporozoite protein (CSP) vaccine in adjuvant, to volunteers previously immunized with a P. falciparum CSP DNA vaccine (VCL-2510) and to naïve volunteers. This vaccine regimen was well tolerated and safe. The volunteers who received RTS,S/AS02A alone had, as expected, antibody and CD4(+) T cell responses, but no CD8(+) T cell responses. Volunteers who received PfCSP DNA followed by RTS,S/AS02A had antibody and CD8(+) and CD4(+) T cell responses (Wang et al., submitted). Sequential immunization with DNA and recombinant protein, also called heterologous prime-boost, led to enhanced immune responses as compared to DNA or recombinant protein alone, suggesting that it might provide enhanced protective immunity.
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60
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Sun P, Schwenk R, White K, Stoute JA, Cohen J, Ballou WR, Voss G, Kester KE, Heppner DG, Krzych U. Protective immunity induced with malaria vaccine, RTS,S, is linked to Plasmodium falciparum circumsporozoite protein-specific CD4+ and CD8+ T cells producing IFN-gamma. THE JOURNAL OF IMMUNOLOGY 2004; 171:6961-7. [PMID: 14662904 DOI: 10.4049/jimmunol.171.12.6961] [Citation(s) in RCA: 198] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The Plasmodium falciparum circumsporozoite (CS) protein-based pre-erythrocytic stage vaccine, RTS,S, induces a high level of protection against experimental sporozoite challenge. The immune mechanisms that constitute protection are only partially understood, but are presumed to rely on Abs and T cell responses. In the present study we compared CS protein peptide-recalled IFN-gamma reactivity of pre- and RTS,S-immune lymphocytes from 20 subjects vaccinated with RTS,S. We observed elevated IFN-gamma in subjects protected by RTS,S; moreover, both CD4(+) and CD8(+) T cells produced IFN-gamma in response to CS protein peptides. Significantly, protracted protection, albeit observed only in two of seven subjects, was associated with sustained IFN-gamma response. This is the first study demonstrating correlation in a controlled Plasmodia sporozoite challenge study between protection induced by a recombinant malaria vaccine and Ag-specific T cell responses. Field-based malaria vaccine studies are in progress to validate the establishment of this cellular response as a possible in vitro correlate of protective immunity to exo-erythrocytic stage malaria vaccines.
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61
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Hirunpetcharat C, Wipasa J, Sakkhachornphop S, Nitkumhan T, Zheng YZ, Pichyangkul S, Krieg AM, Walsh DS, Heppner DG, Good MF. CpG oligodeoxynucleotide enhances immunity against blood-stage malaria infection in mice parenterally immunized with a yeast-expressed 19 kDa carboxyl-terminal fragment of Plasmodium yoelii merozoite surface protein-1 (MSP1(19)) formulated in oil-based Montanides. Vaccine 2003; 21:2923-32. [PMID: 12798636 DOI: 10.1016/s0264-410x(03)00132-4] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The 19kDa carboxyl-terminal fragment of Plasmodium yoelii merozoite surface protein-1 (MSP1(19)), an analog of the leading falciparum malaria vaccine candidate, induces protective immunity to challenge infection when formulated with complete/incomplete Freund's adjuvant (CFA/IFA), an adjuvant unsuitable for use in humans. In this study, we investigate Montanide ISA51 and Montanide ISA720 as well as CpG oligodeoxynucleotide (ODN) as adjuvants for induction of immunity to MSP1(19). Mice immunized with MSP1(19) adjuvanted with Montanide ISA51 were protected even though some mice experienced low-grade parasitemia before resolving the infection. Mice immunized with MSP1(19) adjuvanted with Montanide ISA720 showed delayed patent parasitemia with all mice ultimately succumbing to infection. Interestingly, when the synthetic CpG ODN 1826 was included in either Montanide formulation, mice were completely protected with no parasites detected in the blood. MSP1(19)-specific antibodies in MSP1(19)-immunized mice adjuvanted with Montanide ISA51 or Montanide ISA720 showed predominantly IgG1 antibody and low levels of IgG2a. CpG ODN 1826 significantly enhanced both IgG1 and IgG2a antibody responses in Montanide ISA51-adjuvanted mice but significantly enhanced only the IgG2a antibody response in Montanide ISA720-adjuvanted mice. To investigate the relative roles of antibody and CD4(+) T cells in protection, MSP1(19)-immunized mice adjuvanted with Montanide ISA720 and CpG ODN 1826 were depleted of CD4(+) T cells just prior to challenge. Results showed that three of nine immunized/T cell depleted mice died following infection. These results suggest that antibody and CD4(+) T cells are critical for protection following immunization with MSP1(19) adjuvanted with Montanide and CpG ODN and that the formulation of a human malaria vaccine candidate in Montanide ISA720 or ISA51 together with human compatible CpG ODN would be useful for improving efficacy.
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62
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McConkey SJ, Reece WHH, Moorthy VS, Webster D, Dunachie S, Butcher G, Vuola JM, Blanchard TJ, Gothard P, Watkins K, Hannan CM, Everaere S, Brown K, Kester KE, Cummings J, Williams J, Heppner DG, Pathan A, Flanagan K, Arulanantham N, Roberts MTM, Roy M, Smith GL, Schneider J, Peto T, Sinden RE, Gilbert SC, Hill AVS. Enhanced T-cell immunogenicity of plasmid DNA vaccines boosted by recombinant modified vaccinia virus Ankara in humans. Nat Med 2003; 9:729-35. [PMID: 12766765 DOI: 10.1038/nm881] [Citation(s) in RCA: 465] [Impact Index Per Article: 22.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2003] [Accepted: 04/25/2003] [Indexed: 02/07/2023]
Abstract
In animals, effective immune responses against malignancies and against several infectious pathogens, including malaria, are mediated by T cells. Here we show that a heterologous prime-boost vaccination regime of DNA either intramuscularly or epidermally, followed by intradermal recombinant modified vaccinia virus Ankara (MVA), induces high frequencies of interferon (IFN)-gamma-secreting, antigen-specific T-cell responses in humans to a pre-erythrocytic malaria antigen, thrombospondin-related adhesion protein (TRAP). These responses are five- to tenfold higher than the T-cell responses induced by the DNA vaccine or recombinant MVA vaccine alone, and produce partial protection manifest as delayed parasitemia after sporozoite challenge with a different strain of Plasmodium falciparum. Such heterologous prime-boost immunization approaches may provide a basis for preventative and therapeutic vaccination in humans.
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63
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Forney JR, Wongsrichanalai C, Magill AJ, Craig LG, Sirichaisinthop J, Bautista CT, Miller RS, Ockenhouse CF, Kester KE, Aronson NE, Andersen EM, Quino-Ascurra HA, Vidal C, Moran KA, Murray CK, DeWitt CC, Heppner DG, Kain KC, Ballou WR, Gasser RA. Devices for rapid diagnosis of Malaria: evaluation of prototype assays that detect Plasmodium falciparum histidine-rich protein 2 and a Plasmodium vivax-specific antigen. J Clin Microbiol 2003; 41:2358-66. [PMID: 12791849 PMCID: PMC156472 DOI: 10.1128/jcm.41.6.2358-2366.2003] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The ParaSight F test was developed as a pioneer industry effort in the large-scale, process-controlled production of a device for the rapid diagnosis of malaria. This device performed well in field settings but was limited to the detection of a single malaria species, Plasmodium falciparum. The ParaSight F+V assay advanced upon the ParaSight F test format by incorporating a monoclonal antibody directed against a proprietary Plasmodium vivax-specific antigen, in addition to the antibody directed against P. falciparum histidine-rich protein 2, which was used in the ParaSight F assay. The modified assay was developed to add the capability to detect P. falciparum and P. vivax in a single-test-strip format. The present study evaluated three distinct ParaSight F+V prototypes with samples from symptomatic patients in regions of Thailand and Peru where malaria is endemic. Over a 2-year enrollment period (1998 and 1999), a total of 4,894 patients consented to participation in the study. Compared with the results for duplicate microscopic examinations of Giemsa-stained blood smears as the reference diagnostic standard, each successive prototype showed substantial improvement in performance. The final ParaSight F+V prototype, evaluated in 1999, had an overall sensitivity for detection of asexual P. falciparum parasites of 98%. The sensitivity of the device was 100% for P. falciparum densities of >500 parasites/ micro l, with a sensitivity of 83% for parasite densities of </=500/ micro l. The specificity for the exclusion of P. falciparum was 93%. For P. vivax, the overall sensitivity was 87% for the final 1999 prototype. The sensitivities calculated for different levels of P. vivax parasitemia were 99% for parasite densities of >5,000/ micro l, 92% for parasite densities of 1,001 to 5,000/ micro l, 94% for parasite densities of 501 to 1,000/ micro l, and 55% for parasite densities of 1 to 500/ micro l. The specificity for the exclusion of P. vivax was 87%. The areas under the receiver operating characteristic curves for the diagnostic performance of the assay for the detection of P. falciparum and P. vivax were 0.8907 and 0.8522, respectively. These findings indicate that assays for rapid diagnosis have the potential to enhance diagnostic capabilities in those instances in which skilled microscopy is not readily available.
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64
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Angov E, Aufiero BM, Turgeon AM, Van Handenhove M, Ockenhouse CF, Kester KE, Walsh DS, McBride JS, Dubois MC, Cohen J, Haynes JD, Eckels KH, Heppner DG, Ballou WR, Diggs CL, Lyon JA. Development and pre-clinical analysis of a Plasmodium falciparum Merozoite Surface Protein-1(42) malaria vaccine. Mol Biochem Parasitol 2003; 128:195-204. [PMID: 12742586 DOI: 10.1016/s0166-6851(03)00077-x] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Merozoite Surface Protein-1(42) (MSP-1(42)) is a leading vaccine candidate against erythrocytic malaria parasites. We cloned and expressed Plasmodium falciparum MSP-1(42) (3D7 clone) in Escherichia coli. The antigen was purified to greater than 95% homogeneity by using nickel-, Q- and carboxy-methyl (CM)-substituted resins. The final product, designated Falciparum Merozoite Protein-1 (FMP1), had endotoxin levels significantly lower than FDA standards. It was structurally correct based on binding conformation-dependent mAbs, and was stable. Functional antibodies from rabbits vaccinated with FMP1 in Freund's adjuvant inhibited parasite growth in vitro and also inhibited secondary processing of MSP-1(42). FMP1 formulated with GlaxoSmithKline Biologicals (GSK) adjuvant, AS02A or alum was safe and immunogenic in rhesus (Macaca mulatta) monkeys.
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65
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Garçon N, Heppner DG, Cohen J. Development of RTS,S/AS02: a purified subunit-based malaria vaccine candidate formulated with a novel adjuvant. Expert Rev Vaccines 2003; 2:231-8. [PMID: 12899574 DOI: 10.1586/14760584.2.2.231] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
During the past decade, tremendous progress has been made in process development allowing for the production of large quantities of recombinant antigens, as well as in the understanding of the immune mechanisms underlying protection. Parallel to this, various and numerous adjuvant systems have been developed and tested in animal models and in clinical trials but have rarely induced protection. This review will discuss the development of a new adjuvant system (AS02) in combination with a malaria vaccine antigen candidate. To date, this vaccine is the only one to demonstrate protection in man in artificial challenge as well as in natural field trials. It has been established that this adjuvant system is capable of eliciting high antibody titers along with strong cell-mediated immunity which both contribute to the efficacy of the vaccine.
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66
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Schwenk R, Asher LV, Chalom I, Lanar D, Sun P, White K, Keil D, Kester KE, Stoute J, Heppner DG, Krzych U. Opsonization by antigen-specific antibodies as a mechanism of protective immunity induced by Plasmodium falciparum circumsporozoite protein-based vaccine. Parasite Immunol 2003; 25:17-25. [PMID: 12753434 DOI: 10.1046/j.1365-3024.2003.00495.x] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Recently conducted trials involving the Plasmodium falciparum circumsporozoite (CS) protein-based RTS,S malaria vaccine yielded unprecedented protection against a challenge with infectious sporozoites (spzs). The RTS,S vaccine induced high titres of CS protein-specific antibodies (Abs) in many of the protected volunteers, but the contribution of these Abs to protection remains unknown. Because opsonization by Ab promotes the uptake and destruction of spzs by monocytes and macrophages in both rodent and primate malaria, we asked if the RTS,S-induced Abs have antigen-specific opsonizing activity. Screening plasma from a large number of subjects using spzs was impractical, therefore we developed an alternative assay based on cytofluorometry that allowed the detection of fluoresceinated-Ag-Ab complexes endocytosed by the FcR+ THP-1 human monocyte line. The results showed that plasma samples from RTS,S-immunized subjects contained opsonizing CS protein-specific Abs and the endocytic activity of these Abs in protected subjects was significantly higher than in subjects who were susceptible to infection with spzs. We also demonstrated by electron microscopy that live spzs exposed to RTS,S-immune plasma could be internalized by the THP-1 cells. These results suggest that opsonization by CS protein-specific Abs might be one of the mechanisms that contributes to RTS,S-induced protective immunity.
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67
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Ballou WR, Kester KE, Heppner DG. Pre-erythrocytic malaria vaccines to prevent Plasmodium falciparum malaria. CHEMICAL IMMUNOLOGY 2002; 80:253-61. [PMID: 12058643] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/25/2023]
MESH Headings
- Adult
- Animals
- Anopheles/parasitology
- Antigens, Protozoan/genetics
- Antigens, Protozoan/immunology
- Clinical Trials as Topic
- Drug Design
- Feasibility Studies
- Gambia
- Humans
- Immunization
- Insect Vectors/parasitology
- Malaria Vaccines/adverse effects
- Malaria Vaccines/immunology
- Malaria, Falciparum/immunology
- Malaria, Falciparum/parasitology
- Malaria, Falciparum/prevention & control
- Male
- Models, Animal
- Pilot Projects
- Plasmodium falciparum/genetics
- Plasmodium falciparum/growth & development
- Plasmodium falciparum/immunology
- Protozoan Proteins/genetics
- Protozoan Proteins/immunology
- Rodentia
- Vaccines, DNA/immunology
- Vaccines, Subunit/adverse effects
- Vaccines, Subunit/immunology
- Vaccines, Synthetic/adverse effects
- Vaccines, Synthetic/immunology
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68
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Dutta S, Lalitha PV, Ware LA, Barbosa A, Moch JK, Vassell MA, Fileta BB, Kitov S, Kolodny N, Heppner DG, Haynes JD, Lanar DE. Purification, characterization, and immunogenicity of the refolded ectodomain of the Plasmodium falciparum apical membrane antigen 1 expressed in Escherichia coli. Infect Immun 2002; 70:3101-10. [PMID: 12011004 PMCID: PMC127972 DOI: 10.1128/iai.70.6.3101-3110.2002] [Citation(s) in RCA: 96] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The apical membrane antigen 1 (AMA1) has emerged as a promising vaccine candidate against malaria. Advanced evaluation of its protective efficacy in humans requires the production of highly purified and correctly folded protein. We describe here a process for the expression, fermentation, refolding, and purification of the recombinant ectodomain of AMA1 (amino acids 83(Gly) to 531(Glu)) of Plasmodium falciparum (3D7) produced in Escherichia coli. A synthetic gene containing an E. coli codon bias was cloned into a modified pET32 plasmid, and the recombinant protein was produced by using a redox-modified E. coli strain, Origami (DE3). A purification process was developed that included Sarkosyl extraction followed by affinity purification on a Ni-nitrilotriacetic acid column. The recombinant AMA1 was refolded in the presence of reduced and oxidized glutathione and further purified by using two ion-exchange chromatographic steps. The final product, designated AMA1/E, was homogeneous, monomeric, and >99% pure and had low endotoxin content and low host cell contamination. Analysis of AMA1/E showed that it had the predicted primary sequence, and tertiary structure analysis confirmed its compact disulfide-bonded nature. Rabbit antibodies made to the protein recognized the native parasite AMA1 and inhibited the growth of the P. falciparum homologous 3D7 clone in an in vitro assay. Reduction-sensitive epitopes on AMA1/E were shown to be necessary for the production of inhibitory anti-AMA1 antibodies. AMA1/E was recognized by a conformation-dependent, growth-inhibitory monoclonal antibody, 4G2dc1. The process described here was successfully scaled up to produce AMA1/E protein under GMP conditions, and the product was found to induce highly inhibitory antibodies in rabbits.
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69
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Hoffman SL, Goh LML, Luke TC, Schneider I, Le TP, Doolan DL, Sacci J, de la Vega P, Dowler M, Paul C, Gordon DM, Stoute JA, Church LWP, Sedegah M, Heppner DG, Ballou WR, Richie TL. Protection of humans against malaria by immunization with radiation-attenuated Plasmodium falciparum sporozoites. J Infect Dis 2002; 185:1155-64. [PMID: 11930326 DOI: 10.1086/339409] [Citation(s) in RCA: 519] [Impact Index Per Article: 23.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2001] [Revised: 11/19/2001] [Indexed: 11/03/2022] Open
Abstract
During 1989-1999, 11 volunteers were immunized by the bites of 1001-2927 irradiated mosquitoes harboring infectious sporozoites of Plasmodium falciparum (Pf) strain NF54 or clone 3D7/NF54. Ten volunteers were first challenged by the bites of Pf-infected mosquitoes 2-9 weeks after the last immunization, and all were protected. A volunteer challenged 10 weeks after the last immunization was not protected. Five previously protected volunteers were rechallenged 23-42 weeks after a secondary immunization, and 4 were protected. Two volunteers were protected when rechallenged with a heterologous Pf strain (7G8). In total, there was protection in 24 of 26 challenges. These results expand published findings demonstrating that immunization by exposure to thousands of mosquitoes carrying radiation-attenuated Pf sporozoites is safe and well tolerated and elicits strain-transcendent protective immunity that persists for at least 42 weeks.
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70
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Heppner DG, Cummings JF, Ockenhouse C, Kester KE, Lyon JA, Gordon DM. New World monkey efficacy trials for malaria vaccine development: critical path or detour? Trends Parasitol 2001; 17:419-25. [PMID: 11530353 DOI: 10.1016/s1471-4922(01)02012-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Neither GMP malaria antigens nor GMP vaccines have been compared for efficacy in monkeys and humans. It is too risky to base categorical (go/no go) development decisions on results obtained using partially characterized (non-GMP) antigens, adjuvants that are too toxic for human use or unvalidated primate models. Such practices will lead to serious errors (e.g. failure to identify and stop flawed efforts, rejection of effective vaccine strategies) and unjustifiable delays. Successful malaria vaccine development will emphasize definitive field trials in populations at risk of malaria to define and improve vaccine efficacy.
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71
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Forney JR, Magill AJ, Wongsrichanalai C, Sirichaisinthop J, Bautista CT, Heppner DG, Miller RS, Ockenhouse CF, Gubanov A, Shafer R, DeWitt CC, Quino-Ascurra HA, Kester KE, Kain KC, Walsh DS, Ballou WR, Gasser RA. Malaria rapid diagnostic devices: performance characteristics of the ParaSight F device determined in a multisite field study. J Clin Microbiol 2001; 39:2884-90. [PMID: 11474008 PMCID: PMC88255 DOI: 10.1128/jcm.39.8.2884-2890.2001] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Microscopic detection of parasites has been the reference standard for malaria diagnosis for decades. However, difficulty in maintaining required technical skills and infrastructure has spurred the development of several nonmicroscopic malaria rapid diagnostic devices based on the detection of malaria parasite antigen in whole blood. The ParaSight F test is one such device. It detects the presence of Plasmodium falciparum-specific histidine-rich protein 2 by using an antigen-capture immunochromatographic strip format. The present study was conducted at outpatient malaria clinics in Iquitos, Peru, and Maesod, Thailand. Duplicate, blinded, expert microscopy was employed as the reference standard for evaluating device performance. Of 2,988 eligible patients, microscopy showed that 547 (18%) had P. falciparum, 658 (22%) had P. vivax, 2 (0.07%) had P. malariae, and 1,750 (59%) were negative for Plasmodium. Mixed infections (P. falciparum and P. vivax) were identified in 31 patients (1%). The overall sensitivity of ParaSight F for P. falciparum was 95%. When stratified by magnitude of parasitemia (no. of asexual parasites per microliter of whole blood), sensitivities were 83% (>0 to 500 parasites/microl), 87% (501 to 1,000/microl), 98% (1,001 to 5,000/microl), and 98% (>5,000/microl). Device specificity was 86%.
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72
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Pichyangkul S, Saengkrai P, Yongvanitchit K, Limsomwong C, Gettayacamin M, Walsh DS, Stewart VA, Ballou WR, Heppner DG. Isolation and characterization of rhesus blood dendritic cells using flow cytometry. J Immunol Methods 2001; 252:15-23. [PMID: 11334961 DOI: 10.1016/s0022-1759(01)00327-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Recognition of dendritic cells (DCs) as initiators and modulators of immune responses and growing use of rhesus monkeys for the preclinical optimization of vaccine formulations prompted characterization of the phenotype and function of isolated rhesus peripheral blood DCs. We developed a flow cytometric method to directly identify and isolate DCs from rhesus peripheral blood whereby a T cell depleted population negative for CD3, CD14, CD16 and CD20 but positive for CD83 yielded a cell population with surface markers, morphology, and a cytokine profile similar to human myeloid DCs. Rhesus blood DCs were more effective than monocytes and B cells in mixed lymphocyte reactions and in the presentation of recombinant malaria blood stage antigen MSP-1((42)) to autologous T cells. The ability to isolate rhesus blood DC from peripheral blood should be a useful tool for immunological investigations.
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73
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Pattanapanyasat K, Kotipun K, Yongvanitchit K, Hider RC, Kyle DE, Heppner DG, Walsh DS. Effects of hydroxypyridinone iron chelators in combination with antimalarial drugs on the in vitro growth of Plasmodium falciparum. THE SOUTHEAST ASIAN JOURNAL OF TROPICAL MEDICINE AND PUBLIC HEALTH 2001; 32:64-9. [PMID: 11485097] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/21/2023]
Abstract
Using standard in vitro drug susceptibility methods, we assessed the antimalarial activity of 3 orally administered iron chelators (hydroxypyridinones) alone and in combination with conventional antimalarials drugs (quinine, mefloquine, artesunate, tetracycline, atovaquone) against a chloroquine-resistant Plasmodium falciparum isolate. When tested alone, all iron chelators and antimalarial compounds inhibited the growth of the parasites. IC50 values for iron chelators were 60-70 microM, whereas the IC50 values for antimalarial drugs were in nM ranges, with artesunate being the most potent. The derived isobolograms for the interaction of hydroxypyridinones and antimalarial drugs showed addition or mild antagonism, similar to desferroxamine (Sum of Fractional Inhibitory Concentration, sigma FIC < 0.5 or > 4.0). Despite the absence of synergy with conventional drugs, intrinsic antimalarial activity of hydroxypyridinones supports the continued assessment of these iron chelators as treatment adjuncts.
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74
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Kester KE, McKinney DA, Tornieporth N, Ockenhouse CF, Heppner DG, Hall T, Krzych U, Delchambre M, Voss G, Dowler MG, Palensky J, Wittes J, Cohen J, Ballou WR. Efficacy of recombinant circumsporozoite protein vaccine regimens against experimental Plasmodium falciparum malaria. J Infect Dis 2001; 183:640-7. [PMID: 11170991 DOI: 10.1086/318534] [Citation(s) in RCA: 207] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2000] [Revised: 11/08/2000] [Indexed: 11/03/2022] Open
Abstract
After initial successful evaluation of the circumsporozoite-based vaccine RTS,S/SBAS2, developed by SmithKline Beecham Biologicals with the Walter Reed Army Institute of Research, protective efficacy of several regimens against Plasmodium falciparum challenge was determined. A controlled phase 1/2a study evaluated 1 or 2 standard doses of RTS,S/SBAS2 in 2 groups whose members received open-label therapy and 3 immunizations in blinded groups who received standard, one-half, or one-fifth doses. RTS,S/SBAS2 was safe and immunogenic in all groups. Of the 41 vaccinees and 23 control subjects who underwent sporozoite challenge, malaria developed in 7 of 10 who received 1 dose, in 7 of 14 who received 2 doses, in 3 of 6 who received 3 standard doses, in 3 of 7 who received 3 one-half doses, in 3 of 4 who received 3 one-fifth doses, and in 22 of 23 control subjects. Overall protective efficacy of RTS,S/SBAS2 was 41% (95% confidence interval, 22%-56%; P=.0006). This and previous studies have shown that 2 or 3 doses of RTS,S/SBAS2 protect against challenge with P. falciparum sporozoites.
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75
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Pichyangkul S, Yongvanitchit K, Kum-arb U, Krieg AM, Heppner DG, Walsh DS. Whole blood cultures to assess the immunostimulatory activities of CpG oligodeoxynucleotides. J Immunol Methods 2001; 247:83-94. [PMID: 11150539 DOI: 10.1016/s0022-1759(00)00320-3] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Specially designed oligodeoxynucleotide (ODN) sequences known as 'CpG' ODNs elicit innate and acquired immune responses. In general, screening of new CpG ODNs has been conducted by conventional lymphoproliferative assays or expression of activation markers in peripheral blood mononuclear cell (PBMC) cultures. Here, we compared conventional in vitro human PBMC assays with whole blood assays for screening the immunostimulatory properties of CpG ODNs. Commercially available DNA preparations and mycobacterial-based adjuvants were used as comparators. Activation was assessed by flow cytometry and cytokine production. CpG ODNs, identified by four-letter codes, consisted of 2006 (strong human cell stimulant), 1826 (strong murine cell stimulant), 1840 (weak immunostimulant), and 2041, a non-CpG ODN. In both test systems, and in accordance with previous reports, 2006 was an effective up-regulator of CD40 on human dendritic cells (DC1, DC2), monocytes, and B cells, and of CD69 on NK cells. In contrast to murine cells exposed to CpG ODNs, IL-12 (p40) and IFN-gamma production in human immune cells was negligible, but greatly enhanced by adding GM-CSF. Like 2006, two comparator mycobacterial adjuvant formulations activated DC1, DC2, monocytes and natural killer (NK) cells, but only 2006 had a strong effect on B cells. The usefulness of the whole blood assay was further demonstrated by studies in small volumes of umbilical cord mononuclear cells, that like adult blood cells, showed up-regulation of CD40 expression on B cells, DC, and monocytes, and CD69 on NK cells. The whole blood assay, in conjunction with flow cytometry, is useful for assessing the immunological properties of CpG ODN sequences.
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