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Cummings JF, Polhemus ME, Kester KE, Ockenhouse CF, Gasser RA, Coyne P, Wortmann G, Nielsen RK, Schaecher K, Holland CA, Krzych U, Tornieporth N, Soisson LA, Angov E, Heppner DG. A phase IIa, randomized, double-blind, safety, immunogenicity and efficacy trial of Plasmodium falciparum vaccine antigens merozoite surface protein 1 and RTS,S formulated with AS02 adjuvant in healthy, malaria-naïve adults. Vaccine 2024; 42:3066-3074. [PMID: 38584058 DOI: 10.1016/j.vaccine.2024.03.072] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Revised: 03/15/2024] [Accepted: 03/25/2024] [Indexed: 04/09/2024]
Abstract
BACKGROUND To improve the efficacy of Plasmodium falciparum malaria vaccine RTS,S/AS02, we conducted a study in 2001 in healthy, malaria-naïve adults administered RTS,S/AS02 in combination with FMP1, a recombinant merozoite surface-protein-1, C-terminal 42kD fragment. METHODS A double-blind Phase I/IIa study randomized N = 60 subjects 1:1:1:1 to one of four groups, N = 15/group, to evaluate safety, immunogenicity, and efficacy of intra-deltoid half-doses of RTS,S/AS02 and FMP1/AS02 administered in the contralateral (RTS,S + FMP1-separate) or same (RTS,S + FMP1-same) sites, or FMP1/AS02 alone (FMP1-alone), or RTS,S/AS02 alone (RTS,S-alone) on a 0-, 1-, 3-month schedule. Subjects receiving three doses of vaccine and non-immunized controls (N = 11) were infected with homologous P. falciparum 3D7 sporozoites by Controlled Human Malaria Infection (CHMI). RESULTS Subjects in all vaccination groups experienced mostly mild or moderate local and general adverse events that resolved within eight days. Anti-circumsporozoite antibody levels were lower when FMP1 and RTS,S were co-administered at the same site (35.0 µg/mL: 95 % CI 20.3-63), versus separate arms (57.4 µg/mL: 95 % CI 32.3-102) or RTS,S alone (62.0 µg/mL: 95 % CI: 37.8-101.8). RTS,S-specific lymphoproliferative responses and ex vivo ELISpot CSP-specific interferon-gamma (IFN-γ) responses were indistinguishable among groups receiving RTS,S/AS02. There was no difference in antibody to FMP1 among groups receiving FMP1/AS02. After CHMI, groups immunized with a RTS,S-containing regimen had ∼ 30 % sterile protection against parasitemia, and equivalent delays in time-to-parasitemia. The FMP1/AS02 alone group showed no sterile immunity or delay in parasitemia. CONCLUSION Co-administration of RTS,S and FMP1/AS02 reduced anti-RTS,S antibody, but did not affect tolerability, cellular immunity, or efficacy in a stringent CHMI model. Absence of efficacy or delay of patency in the sporozoite challenge model in the FMP1/AS02 group did not rule out efficacy of FMP1/AS02 in an endemic population. However, a Phase IIb trial of FMP1/AS02 in children in malaria-endemic Kenya did not demonstrate efficacy against natural infection. CLINICALTRIALS gov identifier: NCT01556945.
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Affiliation(s)
- J F Cummings
- Walter Reed Army Institute of Research, Silver Spring, MD, USA
| | - M E Polhemus
- Walter Reed Army Institute of Research, Silver Spring, MD, USA
| | - K E Kester
- Walter Reed Army Institute of Research, Silver Spring, MD, USA
| | - C F Ockenhouse
- Walter Reed Army Institute of Research, Silver Spring, MD, USA
| | - R A Gasser
- Walter Reed Army Institute of Research, Silver Spring, MD, USA
| | - P Coyne
- Walter Reed Army Institute of Research, Silver Spring, MD, USA
| | - G Wortmann
- Walter Reed Army Institute of Research, Silver Spring, MD, USA
| | - R K Nielsen
- Walter Reed Army Institute of Research, Silver Spring, MD, USA
| | - K Schaecher
- Walter Reed Army Institute of Research, Silver Spring, MD, USA
| | - C A Holland
- Walter Reed Army Institute of Research, Silver Spring, MD, USA
| | - U Krzych
- Walter Reed Army Institute of Research, Silver Spring, MD, USA
| | | | - L A Soisson
- Malaria Vaccine Development Program, United States Agency for International Development, Washington, DC, USA
| | - E Angov
- Walter Reed Army Institute of Research, Silver Spring, MD, USA.
| | - D G Heppner
- Walter Reed Army Institute of Research, Silver Spring, MD, USA
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Pichyangkul S, Tongtawe P, Kum-Arb U, Yongvanitchit K, Gettayacamin M, Hollingdale MR, Limsalakpetch A, Stewart VA, Lanar DE, Dutta S, Angov E, Ware LA, Bergmann-Leitner ES, House B, Voss G, Dubois MC, Cohen JD, Fukuda MM, Heppner DG, Miller RS. Evaluation of the safety and immunogenicity of Plasmodium falciparum apical membrane antigen 1, merozoite surface protein 1 or RTS,S vaccines with adjuvant system AS02A administered alone or concurrently in rhesus monkeys. Vaccine 2009; 28:452-62. [PMID: 19857448 DOI: 10.1016/j.vaccine.2009.10.022] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [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: 12/22/2008] [Revised: 09/29/2009] [Accepted: 10/07/2009] [Indexed: 11/15/2022]
Abstract
In an effort to broaden the immune response induced by the RTS,S/AS02(A),vaccine, we have evaluated the immunogenicity of the RTS,S antigen when combined with MSP1(42) and with AMA1, antigens derived from the asexual blood stage. The objectives of this study were (i) to determine whether MSP1(42) and AMA1 vaccines formulated with the AS02(A) Adjuvant System were safe and immunogenic in the rhesus monkey model; (ii) to investigate whether MSP1(42) or AMA1 induced immune interference to each other, or to RTS,S, when added singly or in combinations at a single injection site; (iii) in the event of immune interference, to determine if this could be reduced when antigens were administered at separate sites. We found that MSP1(42) and AMA1 were safe and immunogenic, eliciting antibodies, and Th1 and Th2 responses using IFN-gamma and IL-5 as markers. When malaria antigens were delivered together in one formulation, MSP1(42) and RTS,S reduced AMA1-specific antibody responses as measured by ELISA however, only MSP1(42) lowered parasite growth inhibitory activity of anti-AMA1 antibodies as measured by in vitro growth inhibition assay. Unlike RTS,S, MSP1(42) significantly reduced AMA1 IFN-gamma and IL-5 responses. MSP1(42) suppression of AMA1 IFN-gamma responses was not seen in animals receiving RTS,S+AMA1+MSP1(42) suggesting that RTS,S restored IFN-gamma responses. Conversely, AMA1 had no effect on MSP1(42) antibody and IFN-gamma and IL-5 responses. Neither AMA1 alone or combined with MSP1(42) affected RTS,S antibody or IFN-gamma and IL-5 responses. Immune interference by MSP1(42) on AMA1 antibody responses was also evident when AMA1, MSP1(42) and RTS,S were administered concurrently at separate sites. These results suggest that immune interference may be complex and should be considered for the design of multi-antigen, multi-stage vaccines against malaria.
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Affiliation(s)
- S Pichyangkul
- Department of Immunology and Medicine, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand.
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Macete E, Aponte JJ, Guinovart C, Sacarlal J, Ofori-Anyinam O, Mandomando I, Espasa M, Bevilacqua C, Leach A, Dubois MC, Heppner DG, Tello L, Milman J, Cohen J, Dubovsky F, Tornieporth N, Thompson R, Alonso PL. Safety and immunogenicity of the RTS,S/AS02A candidate malaria vaccine in children aged 1-4 in Mozambique. Trop Med Int Health 2007; 12:37-46. [PMID: 17207146 DOI: 10.1111/j.1365-3156.2006.01754.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [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: 11/29/2022]
Abstract
BACKGROUND The development of a malaria vaccine remains a public health priority for sub-Saharan Africa. RTS,S/AS02A candidate malaria vaccine has been shown to be safe and immunogenic in previous studies in adults and staggered dose-escalation studies in children in The Gambia. However, genetic features and the intensity of malaria transmission may modify the safety and immune response of a vaccine. OBJECTIVE We carried out a phase I, double-blind randomized controlled trial in 60 children aged 1-4 in Mozambique to evaluate the safety, reactogenicity and immunogenicity of the paediatric vaccine dose (fixed 25 microg RTS,S in 0.25 ml) of RTS,S/AS02A, prior to undertaking a planned larger phase IIb proof-of-concept of efficacy study in the same population. METHOD Children were randomized to receive either RTS,S/AS02A or Engerix-B vaccine. Monitoring of safety and reactogenicity included detailed clinical and laboratory analyses and assessment of adverse events (AEs). RESULTS The RTS,S/AS02A was found to be safe and well tolerated. Serious adverse events were balanced between both groups and none was related to vaccination. The frequency of adverse events reported with RTS, S/AS02A was comparable to previous studies in children. Grade 3 AEs were infrequent (one case of pain, one of fever in each group and some swelling greater than 20 mm in diameter), transient and resolved without sequelae. RTS,S/AS02A was highly immunogenic for anti-circumsporozoite protein antibody response and induced a strong anti-hepatitis-B surface antigen response.
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Affiliation(s)
- E Macete
- Centro de Investigação em Saúde da Manhiça (CISM), Manhiça, Mozambique
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4
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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Affiliation(s)
- C Hirunpetcharat
- Department of Microbiology, Faculty of Public Health, Mahidol University, 420/1 Rajvithi Road, Bangkok 10400, Thailand.
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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Affiliation(s)
- D G Heppner
- Malaria Vaccine Program, Division of Communicable Diseases and Immunology, Walter Reed Army Institute of Research, Silver Spring, MD 20910, USA.
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6
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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] [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
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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Affiliation(s)
- J R Forney
- Walter Reed Army Institute of Research, Washington, D.C., USA.
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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Affiliation(s)
- S Pichyangkul
- Department of Immunology and Medicine, US Army Medical Component, US Armed Forces Research Institute of Medical Science (AFRIMS), 315/6 Rajvithi Road, 10400, Bangkok, Thailand.
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8
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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. Southeast Asian J Trop Med Public Health 2001; 32:64-9. [PMID: 11485097] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [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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Affiliation(s)
- K Pattanapanyasat
- Center of Excellence for Flow Cytometry, Office for Research and Development, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok, Thailand.
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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Affiliation(s)
- K E Kester
- Dept. of Immunology, Walter Reed Army Institute of Research, 503 Robert Grant Ave., Silver Spring, MD 20910, USA.
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10
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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Affiliation(s)
- S Pichyangkul
- Department of Immunology and Medicine, AFRIMS, 315/6 Rajuithi Road, Bangkok, Thailand.
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Brockman A, Price RN, van Vugt M, Heppner DG, Walsh D, Sookto P, Wimonwattrawatee T, Looareesuwan S, White NJ, Nosten F. Plasmodium falciparum antimalarial drug susceptibility on the north-western border of Thailand during five years of extensive use of artesunate-mefloquine. Trans R Soc Trop Med Hyg 2000; 94:537-44. [PMID: 11132385 PMCID: PMC4340572 DOI: 10.1016/s0035-9203(00)90080-4] [Citation(s) in RCA: 137] [Impact Index Per Article: 5.7] [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] [Indexed: 11/30/2022] Open
Abstract
Following a marked decline in the efficacy in vivo of mefloquine between 1990 and 1994, a combination of artesunate (4 mg/kg/d for 3 d) and mefloquine (25 mg/kg) has been used as first line treatment of uncomplicated falciparum malaria in camps for displaced persons located along the north-western border of Thailand. Antimalarial drug susceptibility of fresh isolates of Plasmodium falciparum from this population was evaluated using a radioisotope microdilution assay between 1995 and 1999. In total, 268 isolates were collected, of which 189 were from primary infections and 79 from recrudescent infections. The geometric mean 50% inhibitory concentration (IC50) values from primary infections were: dihydroartemisinin 1.2 ng/mL, artesunate 1.6 ng/mL, artemether 4.8 ng/mL, atovaquone 0.4 ng/mL, lumefantrine 32 ng/mL, chloroquine 149 ng/mL, quinine 354 ng/mL, mefloquine 27 ng/mL and halofantrine 4.1 ng/mL. A significant positive correlation was found between the susceptibility in vitro to artesunate and quinine (r = 0.43, P < 0.001), mefloquine (r = 0.46, P < 0.001), and halofantrine (r = 0.51, P < 0.001). These levels of resistance in vitro are among the highest reported and confirm continuing high level multidrug resistance in this area. Despite intensive use of the combination between 1995 and 1999 there has been a significant improvement in mefloquine sensitivity (P < 0.001) and artesunate sensitivity (P < 0.001). This supports observations in vivo that the combination of artesunate and mefloquine has reversed the previous decline in mefloquine sensitivity.
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Affiliation(s)
- A Brockman
- Shoklo Malaria Research Unit, PO Box 46, Mae Sot 63110, Tak, Thailand
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Wongsrichanalai C, Chuanak N, Tulyayon S, Thanoosingha N, Laoboonchai A, Thimasarn K, Brewer TG, Heppner DG. Comparison of a rapid field immunochromatographic test to expert microscopy for the detection of Plasmodium falciparum asexual parasitemia in Thailand. Acta Trop 1999; 73:263-73. [PMID: 10546844 DOI: 10.1016/s0001-706x(99)00040-6] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.6] [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: 10/18/2022]
Abstract
We assessed a rapid, Plasmodium falciparum histidine rich protein 2 (PfHRP2)-based immunochromatographic test (ICT Malaria Pf Test), for detection of asexual P. falciparum parasitemia in 551 subjects in three groups: (1) symptomatic patients self-referring for diagnosis, (2) villagers in a screening survey, and (3) patients recently treated for P. falciparum malaria. Expert light microscopy was the reference standard. ICT test performance was similar for diagnostic and screening modes. Four findings emerged: (1) test sensitivity correlated directly with parasite density, (2) test band intensity correlated directly with parasite density, (3) persistent test positivity after parasite clearance precludes its use for monitoring early therapeutic responses, and (4) a false negative test at 18,000 parasites/microl is unexplained. We conclude that a strong positive ICT test is highly predictive of falciparum asexual parasitemia for the diagnosis of new cases of falciparum malaria in Thailand, but a negative test result is inadequate to exclude parasitemia < 300/microl, and in some instances, even a higher parasitemia.
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Affiliation(s)
- C Wongsrichanalai
- Department of Immunology & Medicine, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand
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Walsh DS, Looareesuwan S, Wilairatana P, Heppner DG, Tang DB, Brewer TG, Chokejindachai W, Viriyavejakul P, Kyle DE, Milhous WK, Schuster BG, Horton J, Braitman DJ, Brueckner RP. Randomized dose-ranging study of the safety and efficacy of WR 238605 (Tafenoquine) in the prevention of relapse of Plasmodium vivax malaria in Thailand. J Infect Dis 1999; 180:1282-7. [PMID: 10479159 DOI: 10.1086/315034] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.0] [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: 11/04/2022] Open
Abstract
WR 238605 is an 8-aminoquinoline developed for the radical cure of Plasmodium vivax. Forty-four P. vivax-infected patients were randomly assigned to 1 of 4 treatment regimens: 3 groups received a blood schizonticidal dose of chloroquine followed by WR 238605: group A (n=15) received 300 mg daily for 7 days; group B (n=11), 500 mg daily for 3 days, repeated 1 week after the initial dose; group C (n=9), 1 dose of 500 mg. A fourth group (D; n=9) received chloroquine only. Among patients who completed 2-6 months of follow-up (n=23), there was 1 relapse in group B (day 120) and 1 in group C (day 112). Among patients treated with chloroquine only, there were 4 relapses (days 40, 43, 49, and 84). WR 238605 was safe, well tolerated, and effective in preventing P. vivax relapse.
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Affiliation(s)
- D S Walsh
- Department of Immunology, US Army Medical Component, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand.
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14
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Ballou WR, Kester KE, Stoute JA, Heppner DG. Malaria vaccines: triumphs or tribulations? Parassitologia 1999; 41:403-8. [PMID: 10697893] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/15/2023]
Abstract
A safe and effective malaria vaccine will greatly facilitate efforts to control the global spread of malaria. This paper discusses the conceptual framework for developing malaria vaccines and some of the difficulties that the various approaches face. It emphasizes the role of pre-erythrocytic malaria vaccines, which are designed to protect against malaria infection, rather than simply prevent clinical disease. It describes recent encouraging results in human subjects with the RTS,S vaccine, a promising pre-erythrocytic malaria vaccine candidate.
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Affiliation(s)
- W R Ballou
- Department of Immunology, Walter Reed Army Institute of Research, Washington, DC 20307-5100, USA.
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15
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16
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Price R, Simpson JA, Teja-Isavatharm P, Than MM, Luxemburger C, Heppner DG, Chongsuphajaisiddhi T, Nosten F, White NJ. Pharmacokinetics of mefloquine combined with artesunate in children with acute falciparum malaria. Antimicrob Agents Chemother 1999; 43:341-6. [PMID: 9925529 PMCID: PMC89074 DOI: 10.1128/aac.43.2.341] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.8] [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: 04/22/1998] [Accepted: 11/22/1998] [Indexed: 11/20/2022] Open
Abstract
Combining artemisinin or a derivative with mefloquine increases cure rates in falciparum malaria patients, reduces transmission, and may slow the development of resistance. The combination of artesunate, given for 3 days, and mefloquine is now the treatment of choice for uncomplicated multidrug-resistant falciparum malaria acquired on the western or eastern borders of Thailand. To optimize mefloquine administration in this combination, a prospective study of mefloquine pharmacokinetics was conducted with 120 children (4 to 15 years old) with acute uncomplicated falciparum malaria, who were divided into four age- and sex-matched groups. The patients all received artesunate (4 mg/kg of body weight/day orally for 3 days and mefloquine as either (i) a single dose (25 mg/kg) on day 2 with food, (ii) a split dose (15 mg/kg on day 2 and 10 mg/kg on day 3) with food, (iii) a single dose (25 mg/kg) on day 0 without food, or (iv) a single dose (25 mg/kg) on day 2 without food. Delaying administration of mefloquine until day 2 was associated with a mean (95% confidence interval) increase in estimated oral bioavailability of 72% (36 to 109%). On day 2 coadministration with food did not increase mefloquine absorption significantly, and there were no significant differences between patients receiving split- and single-dose administration. In combination with artesunate, mefloquine administration should be delayed until the second or third day after presentation.
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Affiliation(s)
- R Price
- Shoklo Malaria Research Unit, Mae Sod, Tak Province, Bangkok, Thailand
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17
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Wongsrichanalai C, Wimonwattrawatee T, Sookto P, Laoboonchai A, Heppner DG, Kyle DE, Wernsdorfer WH. In vitro sensitivity of Plasmodium falciparum to artesunate in Thailand. Bull World Health Organ 1999; 77:392-8. [PMID: 10361756 PMCID: PMC2557670] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/12/2023] Open
Abstract
Reported are the in vitro susceptibilities of Plasmodium falciparum to artesunate, mefloquine, quinine and chloroquine of 86 isolates and to dihydroartemisinin of 45 isolates collected from areas of high resistance to mefloquine within Thailand near the borders with Myanmar and Cambodia, and from southern Thailand where P. falciparum is generally still sensitive to mefloquine. All the isolates were highly sensitive to artesunate, but the geometric mean IC50S were higher in isolates from the Thai-Myanmar and Thai-Cambodian borders than in those from southern Thailand. The IC50S for mefloquine and artesunate were strongly correlated (Pearson r = 0.605; n = 86; P < 0.00001). As expected, the in vitro sensitivities to dihydroartemisinin and artesunate were similar and strongly correlated (at IC50, Pearson r = 0.695; n = 45; P < 0.00002). The correlation between the activity of mefloquine and artesunate requires further investigation in order to determine the potential for development of cross-resistance in nature. Our results suggest that combination with mefloquine is not the ideal way of protecting the usefulness of artemisinin and its derivatives. A search for more suitable partner drugs to these compounds and careful regulation of their use are necessary in the interest of ensuring their long therapeutic life span.
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Affiliation(s)
- C Wongsrichanalai
- Armed Forces Research Institute of Medical Sciences (AFRIMS), Bangkok, Thailand
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18
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Heppner DG, Ballou WR. Malaria in 1998: advances in diagnosis, drugs and vaccine development. Curr Opin Infect Dis 1998; 11:519-30. [PMID: 17033417] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Malaria threatens almost half the world's population. Although a concerted worldwide effort might control this disease, the reality is that inadequate and ineffective laboratory diagnosis and treatment conspire in the yearly deaths of 2,000,000 children from malaria. The failure to institute and implement safeguards to maintain the efficacy of new antimalarial drugs is likely to accelerate the emergence of untreatable malaria, creating an ominous parallel to tuberculosis. There is hope. Field expedient, simple and affordable malaria diagnostics are at hand. Artemisinin derivatives remain surprisingly effective against the multiply drug-resistant falciparum malaria of southeast Asia, despite the widespread and unregulated use of these agents. Human trials have begun of WR238605, a promising primaquine replacement that has prophylactic, treatment and transmission-blocking potential. After demonstrating unprecedented protection against homologous challenge, RTS,S, a new sporozite-based malaria vaccine candidate, is now in field trials.
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Affiliation(s)
- D G Heppner
- Department of Immunology, Walter Reed Army Institute of Medical Research, Washington, DC 20307-5100, USA.
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Sabchareon A, Attanath P, Chanthavanich P, Phanuaksook P, Prarinyanupharb V, Poonpanich Y, Mookmanee D, Teja-Isavadharm P, Heppner DG, Brewer TG, Chongsuphajaisiddhi T. Comparative clinical trial of artesunate suppositories and oral artesunate in combination with mefloquine in the treatment of children with acute falciparum malaria. Am J Trop Med Hyg 1998; 58:11-6. [PMID: 9452284 DOI: 10.4269/ajtmh.1998.58.11] [Citation(s) in RCA: 32] [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] [Indexed: 02/06/2023] Open
Abstract
A randomized pilot study to compare the safety and efficacy of artesunate suppositories (15 mg/kg/day for three days) versus oral artesunate (6 mg/kg/day for three days), both in combination with mefloquine (25 mg/kg), was conducted in 52 Thai children with uncomplicated multidrug-resistant falciparum malaria. Forty-five patients (87%) had a full 28-day follow-up in the hospital to assess efficacy and exclude reinfection. Mean [range] times to fever clearance of the two groups were similar (42 hr [15-104] versus 42 hr [6-119]). Artesunate suppositories resulted in significantly longer times to achieve 50% and 90% reductions of the initial parasite counts (17 and 26 hr versus 9 and 15 hr; P < 0.05 and P < 0.001). Time [range] to parasite clearance was longer in the artesunate suppositories group (42 hr [14-93] versus 35 hr [16-69]), but the difference was not significant. The cure rates by days 28 were not significantly different, 92% for artesunate suppository-treated patients and 100% for oral artesunate-treated patients. Both drug regimens are safe and effective. Further studies are needed to characterize the pharmacokinetic properties and the optimum regimen of artesunate suppositories for the treatment of severe malaria.
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Affiliation(s)
- A Sabchareon
- Department of Tropical Pediatrics, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
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Pichyangkul S, Saengkrai P, Yongvanitchit K, Heppner DG, Kyle DE, Webster HK. Regulation of leukocyte adhesion molecules CD11b/CD18 and leukocyte adhesion molecule-1 on phagocytic cells activated by malaria pigment. Am J Trop Med Hyg 1997; 57:383-8. [PMID: 9347950 DOI: 10.4269/ajtmh.1997.57.383] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [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: 02/05/2023] Open
Abstract
There is increasing evidence that inappropriate immune activation induced by parasite products occurs in malaria disease. To further elucidate the role of Plasmodium falciparum-derived products on host immune activation, we studied the expression of leukocyte adhesion molecules (CD11b/CD18 and LAM-1) on neutrophils and monocytes in response to malaria pigment using flow cytometry. Exposure of leukocytes to isolated malaria pigment derived from ruptured schizonts resulted in significant up-regulation of CD11b/CD18 expression and down-regulation of LAM-1 on both neutrophils and monocytes. In contrast, culture supernatants (pigment free) from ruptured schizonts did not alter the expression of CD11b/CD18 and LAM-1. The increase of CD11b/CD18 and the loss of LAM-1 expression occurred simultaneously with the earliest response detected at 10 min and a plateau reached by 60 min. The effect of malaria pigment on leukocyte adhesion molecules was inhibited by EDTA in a dose-dependent manner. Phagocytosis of malaria pigment was also suppressed by EDTA. This observation suggests that phagocytosis of malaria pigment may be a prerequisite for the effect of malaria pigment on the regulation of CD11b/CD18 and LAM-1 expression. Regulation of leukocyte adhesion molecules through up-regulation of CD11b/CD18 and down-regulation of LAM-1 by malaria pigment could promote leukocyte adherence to endothelium in vivo. This increased adherence of malaria pigment-activated leukocytes might induce cytokine (tumor necrosis factor alpha and interleukin-1beta)-mediated increases in capillary permeability resulting in local tissue edema, and a cytokine-mediated increase in adhesion molecule expression causing vascular clogging by adherent red blood cells, and in severe disease by adherent leukocytes.
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Affiliation(s)
- S Pichyangkul
- Department of Immunology and Parasitology, U.S. Army Medical Component, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand
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21
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Migasena S, Heppner DG, Kyle DE, Chongsuphajaisiddhi T, Gordon DM, Suntharasamai P, Permpanich B, Brockman A, Pitiuttutham P, Wongsrichanalai C, Srisuriya P, Phonrat B, Pavanand K, Viravan C, Ballou WR. SPf66 malaria vaccine is safe and immunogenic in malaria naive adults in Thailand. Acta Trop 1997; 67:215-27. [PMID: 9241386 DOI: 10.1016/s0001-706x(97)00061-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [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: 02/04/2023]
Abstract
In preparation for an efficacy trial of malaria vaccine SPf66 in Thailand, a series of overlapping Phase I trials were conducted of US-manufactured SPf66. Here, two clinical lots were evaluated for safety and immunogenicity in a combined open-label trial. Eleven healthy, malaria naive, 18-44 year-old Thai men and women received three doses by subcutaneous injection in alternate arms at 0, 1 and 6 months. Safety was assessed by monitoring local and systemic reactogenicity and laboratory parameters. Common side effects were mild erythema, induration and tenderness at the site of injection which resolved within 24-48 h. At third immunization, two volunteers developed acute bilateral reactions with induration, erythema and pruritus limited to the sites of the second and third immunizations. Eight of 11 volunteers sero-converted by ELISA, six of whom would be classified as high responders by Colombian standards. Eight of 11 volunteers developed a lymphoproliferative response to the SPf66 antigen. Side effects were more common and antibody and lymphoproliferative responses greatest, among the four female volunteers. This initial study of SPf66 malaria vaccine in Asia constitutes an essential link between the initial Phase I study in the US and subsequent field studies in a semi-immune population in a malaria endemic area of Thailand. This study further establishes comparability of US-manufactured SPf66 with that of Colombian provenance and substantiates the validity of the subsequent negative efficacy results of SPf66 in a field trial in Thailand.
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Affiliation(s)
- S Migasena
- Vaccine Trial Center, Mahidol University, Thailand
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22
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23
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Pichyangkul S, Saengkrai P, Yongvanitchit K, Stewart A, Heppner DG. Activation of gammadelta T cells in malaria: interaction of cytokines and a schizont-associated Plasmodium falciparum antigen. J Infect Dis 1997; 176:233-41. [PMID: 9207372 DOI: 10.1086/514029] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.3] [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: 02/04/2023] Open
Abstract
A soluble Plasmodium falciparum antigen that specifically stimulates gammadelta T cells has been found associated predominantly with schizonts rather than ring forms, trophozoites, or gametocytes. This schizont-associated antigen (SAA) is resistant to protease digestion, is anionic at pH 8.5, is heat- and pH-resistant, and contains a phosphate group(s) that is crucial for biologic activity. Partially purified SAA induced proliferative responses and interferon-gamma production by gammadelta T cells. These stimulatory effects were greatly enhanced by monocyte-derived cytokines, interleukin (IL)-10, IL-12, and IL-1beta, but not by tumor necrosis factor-alpha. Taken together, these results suggest that concurrent stimulation of gammadelta T cells by SAA and by cytokines released from activated monocytes (IL-10, IL-12, IL-1beta) may represent the major mechanism underlying the selective activation of gammadelta T cells that is consistently observed in clinical cases of P. falciparum infection.
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Affiliation(s)
- S Pichyangkul
- Department of Immunology and Medicine, US Army Medical Component, AFRIMS, Bangkok, Thailand
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24
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Nosten F, Luxemburger C, Kyle DE, Gordon DM, Ballou WR, Sadoff JC, Brockman A, Permpanich B, Chongsuphajaisiddhi T, Heppner DG. Phase I trial of the SPf66 malaria vaccine in a malaria-experienced population in Southeast Asia. Am J Trop Med Hyg 1997; 56:526-32. [PMID: 9180603 DOI: 10.4269/ajtmh.1997.56.526] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [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: 02/04/2023] Open
Abstract
In preparation for a recently reported, independent field trial of SPf66 malaria vaccine efficacy in Thailand, we first established the safety and immunogenicity of two clinical lots of U.S. manufactured lots of SPf66 in a series of overlapping Phase I studies. The vaccine was produced in approved laboratories using good manufacturing practices. Two clinical lots of alum-adsorbed SPf66 were evaluated in a combined, open-label, Phase I clinical trial involving 50 healthy, malaria-experienced Karen adults and children. Volunteers were grouped by age and immunized sequentially. Group 1 had 30 adults. Group 2 had 10 children 8-15 years of age, and Group 3 had 10 children 2-6 years of age. The SPf66 vaccine was well tolerated in this malaria-experienced population. The most common side effects were erythema, induration, warmth, and tenderness at the site of injection, which typically resolved within 24-48 hr. One adult volunteer developed an acute urticarial rash following the third dose. Among adults, and to a lesser extent older children females had more local reactions than their male counterparts. Seroconversion to SPf66 by enzyme-linked immunosorbent assay occurred in 76% of volunteers receiving two or three doses. This vaccine was safe and immunogenic in malaria-experienced Karen adults and children. This study establishes the comparability of U.S.-manufactured SPf66 with that of Colombian origin, and is important for interpreting the efficacy results of U.S.-manufactured SPf66 in the same study population.
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Affiliation(s)
- F Nosten
- Shokia Malaria Research Unit, Mae Sot, Thailand
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25
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Wongsrichanalai C, Nguyen TD, Trieu NT, Wimonwattrawatee T, Sookto P, Heppner DG, Kawamoto F. In vitro susceptibility of Plasmodium falciparum isolates in Vietnam to artemisinin derivatives and other antimalarials. Acta Trop 1997; 63:151-8. [PMID: 9088428 DOI: 10.1016/s0001-706x(96)00618-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [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: 02/04/2023]
Abstract
We performed in vitro drug susceptibility assays of ten Plasmodium falciparum isolates collected from Vict Nam in 1995. All isolates were found to be highly sensitive to artesunate, dihydro-artemisinin and artemisinin. They were also sensitive to quinine. All of them were resistant to chloroquine and mefloquine in vitro. This study provides the baseline estimates of in vitro susceptibility levels of the Vietnamese isolates to artermisinin and their derivatives because the data were collected soon after these drugs were introduced countrywide. It also describes some quantitative profiles of the in vitro response of other standard antimalarial drugs in Viet Nam, which is presently limited.
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Affiliation(s)
- C Wongsrichanalai
- Armed Forces Research Institute of Medical Sciences (AFRIMS), Bangkok, Thailand
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26
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Stoute JA, Slaoui M, Heppner DG, Momin P, Kester KE, Desmons P, Wellde BT, Garçon N, Krzych U, Marchand M. A preliminary evaluation of a recombinant circumsporozoite protein vaccine against Plasmodium falciparum malaria. RTS,S Malaria Vaccine Evaluation Group. N Engl J Med 1997; 336:86-91. [PMID: 8988885 DOI: 10.1056/nejm199701093360202] [Citation(s) in RCA: 615] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
BACKGROUND The candidate vaccines against malaria are poorly immunogenic and thus have been ineffective in preventing infection. We developed a vaccine based on the circumsporozoite protein of Plasmodium falciparum that incorporates adjuvants selected to enhance the immune response. METHODS The antigen consists of a hybrid in which the circumsporozoite protein fused to hepatitis B surface antigen (HBsAg) is expressed together with unfused HBsAg. We evaluated three formulations of this antigen in an unblinded trial in 46 subjects who had never been exposed to malaria. RESULTS Two of the vaccine formulations were highly immunogenic. Four subjects had adverse systemic reactions that may have resulted from the intensity of the immune response after the second dose, which led us to reduce the third dose. Twenty-two vaccinated subjects and six unimmunized controls underwent a challenge consisting of bites from mosquitoes infected with P. falciparum. Malaria developed in all six control subjects, seven of eight subjects who received vaccine 1, and five of seven subjects who received vaccine 2. In contrast, only one of seven subjects who received vaccine 3 became infected (relative risk of infection, 0.14; 95 percent confidence interval, 0.02 to 0.88; P<0.005). CONCLUSIONS A recombinant vaccine based on fusion of the circumsporozoite protein and HBsAg plus a potent adjuvant can protect against experimental challenge with P. falciparum sporozoites. After additional studies of protective immunity and the vaccination schedule, field trials are indicated for this new vaccine against P. falciparum malaria.
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Affiliation(s)
- J A Stoute
- Walter Reed Army Institute of Research, Washington, D.C. 20307-5100, USA
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27
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Pattanapanyasat K, Yongvanitchit K, Heppner DG, Tongtawe P, Kyle DE, Webster HK. Culture of malaria parasites in two different red blood cell populations using biotin and flow cytometry. Cytometry 1996; 25:287-94. [PMID: 8914826 DOI: 10.1002/(sici)1097-0320(19961101)25:3<287::aid-cyto10>3.0.co;2-s] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
A novel culture system using biotin/streptavidin and flow cytometry was developed to compare maturation and growth rates in Plasmodium falciparum malaria parasites in two distinct red blood cell (RBC) populations. Biotin was used to label a selected RBC population which was then mixed with another distinct unbiotinylated RBC population. P. falciparum-infected RBCs were used to initiate co-cultures followed over 2-3 schizogonic growth cycles. Co-cultures were harvested and stained with streptavidin-fluorescein isothiocyanate (FITC) followed by fixation and staining of parasite DNA. The combination of biotin/streptavidin-FITC and DNA fluorochrome enabled simultaneous flow cytometric analysis of the two different RBC populations and of the parasitemias in each RBC population. We then used this system to study the in vitro susceptibility of RBCs from individuals with hemoglobin H (Hb H) disease to infection and growth of P. falciparum. Significant reduction in parasite multiplication was found in Hb H RBCs as compared with that in normal RBCs. This novel malaria culture system offers two major innovations: a method to compare directly the relative ability of any two red blood cell populations to support malaria parasite invasion and development under identical conditions, and a critical reduction in the volume of blood and reagents needed to assess parasite growth. The application of biotin-labeled RBCs in the flow cytometric analysis of parasite development may offer new insights in studies of the relationship between RBC defects and susceptibility to malaria parasites.
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Affiliation(s)
- K Pattanapanyasat
- Thalassemia Center, Faculty of Medicine at Siriraj Hospital, Bangkok, Thailand
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28
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Nosten F, Luxemburger C, Kyle DE, Ballou WR, Wittes J, Wah E, Chongsuphajaisiddhi T, Gordon DM, White NJ, Sadoff JC, Heppner DG. Randomised double-blind placebo-controlled trial of SPf66 malaria vaccine in children in northwestern Thailand. Shoklo SPf66 Malaria Vaccine Trial Group. Lancet 1996; 348:701-7. [PMID: 8806288 DOI: 10.1016/s0140-6736(96)04465-0] [Citation(s) in RCA: 109] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
BACKGROUND Previous efficacy trials of SPf66 malaria vaccine have produced conflicting results in different populations. We report a randomised double-blind trial of the SPf66 vaccine conducted in Karen children aged 2-15 living in a malarious region of northwestern Thailand. Recombinant hepatitis B vaccine was used as a comparator. METHODS The study had a power of 90% to detect an efficacy of 30%, defined as a reduction in the incidence of first cases of symptomatic falciparum malaria after three doses of vaccine. 1221 children received three immunisations and were eligible for the primary efficacy analysis. Intense active and passive case detection continued over 15 months of follow-up. FINDINGS The SPf66 vaccine was well tolerated, although 26 children had mild or moderately severe local or systemic allergic reactions, compared with none in the comparator group. The vaccine was immunogenic; after three doses, 73% of recipients had seroconverted. There were no deaths due to malaria during the study. During the 15-month period of evaluation there were 379 first cases of symptomatic falciparum malaria (195 in the SPf66 recipients, 184 in the comparator group); an SPf66 efficacy of -9% (95% CI -33 to 14, p = 0.41). No significant differences between the two study groups in parasite density or any other measure of malaria-related morbidity were detected. INTERPRETATION These findings are consistent with a recent study showing lack of efficacy of SPf66 among Gambian infants and differ from earlier positive reports from South America and evidence of borderline efficacy from Tanzania. We conclude that SPf66 does not protect against clinical falciparum malaria and that further efficacy trials are not warranted.
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Affiliation(s)
- F Nosten
- Shoklo Malaria Research Unit, Mae Sot, Thailand
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29
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Heppner DG, Gordon DM, Gross M, Wellde B, Leitner W, Krzych U, Schneider I, Wirtz RA, Richards RL, Trofa A, Hall T, Sadoff JC, Boerger P, Alving CR, Sylvester DR, Porter TG, Ballou WR. Safety, immunogenicity, and efficacy of Plasmodium falciparum repeatless circumsporozoite protein vaccine encapsulated in liposomes. J Infect Dis 1996; 174:361-6. [PMID: 8699067 DOI: 10.1093/infdis/174.2.361] [Citation(s) in RCA: 73] [Impact Index Per Article: 2.6] [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: 02/01/2023] Open
Abstract
Seventeen malaria-naive volunteers received a recombinant Plasmodium falciparum vaccine (RLF) containing the carboxy- and the amino-terminal of the circumsporozoite protein (CSP) antigen without the central tetrapeptide repeats. The vaccine was formulated in liposomes with either a low or high dose of 3-deacylated monophosphoryl lipid A (MPL) and administered with alum by intramuscular injection. Both formulations were well tolerated and immunogenic. MPL increased sporozoite antibody titers measured by ELISA, Western blot, and immunofluorescence assay. One high-dose MPL vaccine formulation recipient developed a CSP-specific cytotoxic T lymphocyte response. After homologous sporozoite challenge, immunized volunteers developed patent malaria. There was no correlation between prepatent period and antibody titers to the amino- or carboxy-terminal. The absence of delay in patency argues against inclusion of the amino-terminal in future vaccines. A significant cytotoxic T lymphocyte response may have been suppressed by the inclusion of alum as an adjuvant.
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MESH Headings
- Adolescent
- Adult
- Antigens, Protozoan/adverse effects
- Antigens, Protozoan/immunology
- Antigens, Protozoan/therapeutic use
- Cytotoxicity, Immunologic
- Dose-Response Relationship, Drug
- Drug Carriers
- Female
- Humans
- Liposomes
- Lymphocyte Activation
- Malaria Vaccines/adverse effects
- Malaria Vaccines/immunology
- Malaria Vaccines/therapeutic use
- Malaria, Falciparum/prevention & control
- Male
- Middle Aged
- Protozoan Proteins/adverse effects
- Protozoan Proteins/immunology
- Protozoan Proteins/therapeutic use
- Repetitive Sequences, Nucleic Acid
- Safety
- Vaccines, Synthetic/adverse effects
- Vaccines, Synthetic/immunology
- Vaccines, Synthetic/therapeutic use
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Affiliation(s)
- D G Heppner
- Department of Membrane Biochemistry, Walter Reed Army Institute of Research, Washington, DC, USA
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Gordon DM, Duffy PE, Heppner DG, Lyon JA, Williams JS, Scheumann D, Farley L, Stacey D, Haynes JD, Sadoff JC, Ballou WR. Phase I safety and immunogenicity testing of clinical lots of the synthetic Plasmodium falciparum vaccine SPf66 produced under good manufacturing procedure conditions in the United States. Am J Trop Med Hyg 1996; 55:63-8. [PMID: 8702024 DOI: 10.4269/ajtmh.1996.55.63] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [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: 02/01/2023] Open
Abstract
Two clinical lots of alum-adsorbed SPf66 vaccine produced in the United States were evaluated in separate, open-label, Phase I clinical trials involving 15 healthy, malaria-naive, 18-45-year old men and women. Subjects received 2 mg doses subcutaneously in alternate arms at 0, one, and six months. Safety was assessed by monitoring local and systemic reactions and laboratory parameters. The most common side effects were erythema and local tenderness at the site of injection, which increased in frequency with subsequent doses of vaccine. These local reactions were considered mild and resolved within 24-48 hr. Eleven of 14 volunteers who received all three doses of vaccine seroconverted by enzyme-linked immunosorbent assay. The distribution of high, medium, and low nonresponders was comparable with that seen in trials of Colombian-produced vaccine. One high responder developed antibodies reactive with asexual stage parasite antigens by immunofluorescence and immunoblot. The results indicated that at full adult doses, SPf66 of U.S. origin is mildly reactogenic and induces immune responses similar to those reported for SPf66 of Colombian origin.
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Affiliation(s)
- D M Gordon
- Department of Immunology, Walter Reed Army Institute of Research, Washington, District of Columbia
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31
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Gordon DM, McGovern TW, Krzych U, Cohen JC, Schneider I, LaChance R, Heppner DG, Yuan G, Hollingdale M, Slaoui M. Safety, immunogenicity, and efficacy of a recombinantly produced Plasmodium falciparum circumsporozoite protein-hepatitis B surface antigen subunit vaccine. J Infect Dis 1995; 171:1576-85. [PMID: 7769295 DOI: 10.1093/infdis/171.6.1576] [Citation(s) in RCA: 215] [Impact Index Per Article: 7.4] [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: 01/27/2023] Open
Abstract
Twenty malaria-naive volunteers received a recombinant Plasmodium falciparum malaria vaccine (RTS,S) containing 19 NANP repeats and the carboxy terminus (amino acids 210-398) of the circumsporozoite (CS) antigen coexpressed in yeast with hepatitis B surface antigen. Ten received vaccine adjuvanted with alum, and 10 received vaccine adjuvanted with alum plus 3-deacylated monophosphoryl lipid A (MPL). Both formulations were well tolerated and immunogenic. MPL enhanced CS antibody levels (measured by ELISA, immunofluorescence, and inhibition of sporozoite invasion assays). After sporozoite challenge, 6 of 6 in the alum group and 6 of 8 in the alum-MPL group developed patent malaria. Protected subjects had higher levels of CS antibody titers on day of challenge than did nonprotected subjects. After immunization, 1 protected subject had increased cytotoxic T lymphocyte activity against CS and recall of memory T cell responses to RTS,S and selected CS.
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Affiliation(s)
- D M Gordon
- Department of Immunology, Walter Reed Army Institute of Research, Washington, DC, USA
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32
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Ballou WR, Blood J, Chongsuphajaissidhi T, Gordon DM, Heppner DG, Kyle DE, Luxemburger C, Nosten F, Sadoff JC, Singhasivanon P. Field trials of an asexual blood stage malaria vaccine: studies of the synthetic peptide polymer SPf66 in Thailand and the analytic plan for a phase IIb efficacy study. Parasitology 1995; 110 Suppl:S25-36. [PMID: 7784126 DOI: 10.1017/s0031182000001463] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [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: 01/27/2023]
Abstract
Several years ago the Walter Reed Army Institute of Research (WRAIR) initiated an independent analysis of the candidate malaria blood stage vaccine SPf66. WRAIR contracted for the synthesis and formulation of SPf66 in United States Food and Drug Administration (FDA) inspected laboratories within the U.S., and in 1992, filed an Investigational New Drug (IND) application with the FDA. Preclinical studies indicated that the vaccine could be synthesized to meet its release specifications, and when adjuvanted with alum, was essentially equivalent to Colombian produced SPf66 in regards to immunogenicity in preclinical studies of rodents and primates, and in human volunteers in Phase I studies. The goal of these efforts was ultimately to conduct a Phase IIb field trial to determine the safety and efficacy of SPf66 produced under current Good Manufacturing Practices (cGMP). Such a trial is currently underway in a malaria endemic refugee camp along the Thai-Burmese border. Here we briefly describe the study and present the formal analytic plan that was submitted to regulatory authorities in the United States for analysis of the study results. We believe such independent confirmatory studies are an essential part of the vaccine development process and are required to provide important data regarding the safety and efficacy of candidate vaccines in diverse geographical regions, and as a means to assess their role in the context of broader malaria control programmes.
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Affiliation(s)
- W R Ballou
- Division of Communicable Diseases and Immunology, WRAIR, Washington, D.C. 20307-5100, USA
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33
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Kuschner RA, Heppner DG, Andersen SL, Wellde BT, Hall T, Schneider I, Ballou WR, Foulds G, Sadoff JC, Schuster B. Azithromycin prophylaxis against a chloroquine-resistant strain of Plasmodium falciparum. Lancet 1994; 343:1396-7. [PMID: 7910886 DOI: 10.1016/s0140-6736(94)92526-7] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Azithromycin has antimalarial activity and favourable pharmacokinetic properties for a prophylactic antimalarial agent. We investigated the ability of azithromycin to prevent malaria in volunteers infected with a chloroquine-resistant strain of Plasmodium falciparum. 4 volunteers received oral azithromycin 500 mg followed by 250 mg daily for 7 further days. Subjects were infected on the third day of azithromycin. 3 subjects were protected compared with none of 15 controls. The volunteer not protected by azithromycin had unquantifiable plasma levels of azithromycin, probably because of poor absorption. Azithromycin could be a promising prophylactic agent for P falciparum malaria.
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Affiliation(s)
- R A Kuschner
- Division of Communicable Diseases, Walter Reed Army Institute of Research, Washington, DC 20307
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Gonzalez C, Hone D, Noriega FR, Tacket CO, Davis JR, Losonsky G, Nataro JP, Hoffman S, Malik A, Nardin E, Sztein MB, Heppner DG, Fouts TR, Isibasi A, Levine MM. Salmonella typhi vaccine strain CVD 908 expressing the circumsporozoite protein of Plasmodium falciparum: strain construction and safety and immunogenicity in humans. J Infect Dis 1994; 169:927-31. [PMID: 8133113 DOI: 10.1093/infdis/169.4.927] [Citation(s) in RCA: 105] [Impact Index Per Article: 3.5] [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: 01/29/2023] Open
Abstract
rcsp, encoding amino acids 21-398 of Plasmodium falciparum circumsporozoite protein (CSP), under control of tacP was integrated into the chromosomal delta aroC locus of attenuated delta aroC, delta aroD Salmonella typhi CVD 908. By immunoblot and ELISA, rCSP expression was greater from a multicopy plasmid than from the single chromosomal gene. CVD 908 omega (delta aroC1019::tacP-rcsp) was well tolerated by 10 volunteers who were fed two doses of 5 x 10(7) organisms 8 days apart. Seven subjects excreted the vaccine strain for 1-3 days. All subjects developed serologic responses to O and H antigens of the live vector, whereas 3 vaccinees responded to the foreign antigen: 1 developed an 80-fold rise in serum anti-sporozoite antibody, another had a 4-fold rise in antibody to a recombinant portion of CSP (residues 309-345), while a third vaccinee developed CSP-specific CD8+ cytotoxic T lymphocyte activity. This is the first report of attenuated S. typhi eliciting a human serologic or a cytotoxic T lymphocyte response to a foreign protein. Improved foreign gene expression should enhance immunogenicity.
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Affiliation(s)
- C Gonzalez
- Center for Vaccine Development, University of Maryland School of Medicine, Baltimore 21201
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Simanjuntak C, Witham N, Punjabi N, Heppner DG, Losonsky G, Totosudirjo H, Rifai AR, Clemens J, Lim YL. Safety and immunogenicity of single-dose live oral cholera vaccine CVD 103-HgR in 5-9-year-old Indonesian children. Lancet 1992; 340:689-94. [PMID: 1355798 DOI: 10.1016/0140-6736(92)92231-4] [Citation(s) in RCA: 125] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Oral vaccines offer great promise as public-health measures to prevent disease in less-developed countries. CVD 103-HgR, a genetically engineered, attenuated, Vibrio cholerae O1 strain has proved effective in industrialised countries. We have assessed the safety, immunogenicity, and excretion of this live cholera vaccine in children in north Jakarta, Indonesia. 412 children aged 5-9 years received single doses of 5 x 10(6), 5 x 10(7), 5 x 10(8), 5 x 10(9), or 1 x 10(10) colony forming units (CFU) of CVD 103-HgR or placebo (5 x 10(8) inactivated Escherichia coli K-12) with buffer. All doses were well tolerated. The 5 x 10(8) CFU dose, which is highly immunogenic in subjects in industrialised countries (greater than 90% seroconversion), elicited seroconversions of vibriocidal antibody in only 16% of Indonesian children. By contrast, a single 5 x 10(9) CFU dose of vaccine resulted in high rates (75% and 87%) of seroconversion with two different batches of vaccine. A batch prepared with a centrifugation step gave significantly higher geometric mean titres (16-fold increase over baseline) than did a batch in which there was a filtration step between fermentation and lyophilisation (10-fold increase over baseline). At a 5 x 10(9) CFU dose, CVD 103-HgR is well tolerated and highly immunogenic in Indonesian children and should therefore be further investigated for use as a one-dose live oral cholera vaccine in developing countries.
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Heppner DG, Hallaway PE, Kontoghiorghes GJ, Eaton JW. Antimalarial properties of orally active iron chelators. Blood 1988; 72:358-61. [PMID: 3291984] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
The appearance of widespread multiple drug resistance in human malaria has intensified the search for new antimalarial compounds. Metal chelators, especially those with high affinity for iron, represent one presently unexploited class of antimalarials. Unfortunately the use of previously identified chelators as antimalarials has been precluded by their toxicity and, in the case of desferrioxamine, the necessity for parenteral administration. The investigators now report that a new class of orally active iron chelators, namely the derivatives of alpha-ketohydroxypyridines (KHPs), are potent antimalarials against cultured Plasmodium falciparum. The KHPs evidently exert this effect by sequestering iron because a preformed chelator:iron complex has no antimalarial action. The pool(s) of iron being sequestered by the chelators have not been identified but may not include serum transferrin. Preincubation of human serum with KHPs followed by removal of the drug results in the removal of greater than 97% of total serum iron. Nonetheless, this serum effectively supports the growth of P falciparum cultures. Therefore the KHPs may exert antimalarial effect through chelation of erythrocytic rather than serum iron pool(s). The investigators conclude that these powerful, orally active iron chelators may form the basis of a new class of antimalarial drugs.
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Affiliation(s)
- D G Heppner
- Department of Medicine, University of Minnesota, Minneapolis 55455
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Dunn JT, Kim PS, Dunn AD, Heppner DG, Moore RC. The role of iodination in the formation of hormone-rich peptides from thyroglobulin. J Biol Chem 1983; 258:9093-9. [PMID: 6874680] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Reduced thyroglobulins from several animal species contain hormone-rich iodopeptides of 20,000-26,000 and 15,000-18,000 daltons. The present study has investigated the role of iodination in their production. Experimental approaches have included: iodination in vitro of thyroglobulin from rabbit thyroid slices incubated with [3H]leucine and subsequent analysis of 3H distribution by gel electrophoresis; iodination in vitro of low iodine thyroglobulin from a human goiter, followed by isolation of the major iodopeptides and quantitation of their peptide content; and injection of iodine-deficient rats with Na125I and assessment of the distribution of isotope among the iodopeptides at successive time intervals. From these experiments the following general pattern has emerged: 1) at low levels of iodine (less than 5 atoms/molecule of thyroglobulin) in vitro or at short time intervals after iodine administration in vivo (less than 4 h), the principal iodinated component of reduced thyroglobulin is a approximately 230,000-dalton peptide; 2) with moderate increases in iodine (5-40 atoms/molecule) or longer time intervals after administration (greater than or equal to 4 h) there is less of the 230,000-dalton iodopeptide, and an iodothyronine-rich approximately 20,000- to 26,000-dalton iodopeptide appears; 3) at higher levels of iodine (greater than 40 atoms/molecule) the amount of approximately 230,000-dalton iodopeptide decreases further, the amount of 20,000- to 26,000-dalton iodopeptides may decrease, and an iodothyronine-rich 15,000- to 18,000-dalton peptide appears. Progressive iodination gives the same changes in distribution of peptide material among these iodopeptides as it does in iodine distribution, and the changes seen with iodination in vitro are similar to those occurring over time in vivo. We conclude that during the process of iodination discrete peptide bonds of thyroglobulin are cleaved to produce the hormone-rich iodopeptides. This is probably a normal part of thyroglobulin maturation in vivo and may be a necessary event preceding hormone formation.
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Dunn JT, Kim PS, Dunn AD, Heppner DG, Moore RC. The role of iodination in the formation of hormone-rich peptides from thyroglobulin. J Biol Chem 1983. [DOI: 10.1016/s0021-9258(17)44635-7] [Citation(s) in RCA: 33] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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Dunn JT, Dunn AD, Heppner DG, Kim PS. A discrete thyroxine-rich iodopeptide of 20,000 daltons from rabbit thyroglobulin. J Biol Chem 1981; 256:942-7. [PMID: 7451481] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
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