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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] [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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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] [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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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] [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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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] [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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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] [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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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] [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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83
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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] [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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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] [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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86
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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] [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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87
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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] [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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89
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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] [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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90
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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] [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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91
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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] [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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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: 625] [Impact Index Per Article: 23.1] [Reference Citation Analysis] [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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93
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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] [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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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] [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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95
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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] [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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96
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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] [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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97
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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] [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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98
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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] [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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99
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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] [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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100
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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] [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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