426 results on '"Louis H. Miller"'
Search Results
402. Binding of infected red cells
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Louis H. Miller
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Multidisciplinary ,Biology - Published
- 1989
403. Electron Microscopy of Knobs in Plasmodium falciparum-Infected Erythrocytes
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Louis H. Miller, John Rabbege, Masamichi Aikawa, and Iroka J. Udeinya
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Scanning electron microscope ,Thin section ,Biology ,law.invention ,chemistry.chemical_compound ,Membrane ,Osmium tetroxide ,chemistry ,Transmission electron microscopy ,Cytoplasm ,law ,parasitic diseases ,Biophysics ,Parasitology ,Glutaraldehyde ,Electron microscope ,Ecology, Evolution, Behavior and Systematics - Abstract
Erythrocytes infected by certain species of malarial parasites show two types of alterations of erythrocyte membranes such as electron-dense protrusions called knobs and caveola-vesicle complexes (Aikawa et al., 1975, Am. J. Path. 79: 285; Aikawa, 1977, Bull. WHO 55:2). The knobs are found on the membrane of erythrocytes infected with falciparum-type malaria parasites. These knobs form focal junctions with the endothelial cell membranes or with the knobs of other erythrocytes, resulting in the sequestration of these infected erythrocytes along the vascular endothelium (Trager et al., 1966, Bull. WHO 35: 883; Luse and Miller, 1971, Am. J. Trop. Med. Hyg. 20: 655; Aikawa et al., 1972, Z. Zellforsch. 124: 72; Udeinya et al., 1981, Science 213: 555). The erythrocyte membrane covering the knobs is immunologically different from the rest of the erythrocyte membrane (Kilejian et al., 1977, Exp. Parasitol. 42: 157; Langreth et al., 1979, J. Exp. Med. 150:1241; Chulay et al., 1981, Am. J. Trop. Med. Hyg. 30: 12). The erythrocytes infected with small trophozoites show few knobs, but they increase in number as the parasite grows within the erythrocyte. Because the morphology of these knobs is still not fully understood, we have attempted to characterize them by transmission and scanning electron microscopy together with freeze-fracture and etch techniques. Plasmodiumfalciparum (Camp strain) in Aotus erythrocytes and P. falciparum (Thailand and Liberian strains) in human erythrocytes were obtained from culture (Udeinya et al., 1981, Science 213: 555). The infected erythrocytes were fixed in 2% glutaraldehyde in 0.1 M cacodylate buffer (pH 7.4) containing 4% sucrose, washed in 0.1 M cacodylate buffer and postfixed for 1 hr in 1% osmium tetroxide. After fixation, the samples were centrifuged and then processed for thin section transmission and scanning electron microscopy. Freeze-fracturing and etching were performed on P. falciparum in human RBC's. Fracturing was carried out at -120 C under a vacuum of 2 X 10-7 Torr. Etching was performed at -100 C, under a vacuum of 2 X 10-7 Torr for 2 min. The surfaces obtained were replicated with platinum and carbon. Replicas were cleaned as described previously (Aikawa et al., 1981, J. Cell Biol. 91: 55). Transmission electron microscopy was performed with a JEOL 100CX electron microscope. Scanning electron microscopy was performed with a JEOL 100CX electron microscope with a scanning unit at 20 kV. Thin-section electron microscopy showed many knobs on the erythrocytes infected with P. falciparum (Fig. 1). Each knob is a cone-shaped, electron-dense structure measuring 30 to 40 nm in height and 9 to 100 nm in width and is covered by the erythrocyte membrane. The base is not sharply demarcated, but gradually merges into the erythrocyte cytoplasm. Scanning electron microscopy showed numerous cone-shaped knobs evenly distributed over the entire erythrocyte surface (Fig. 2). The distribution pattern of the knobs was more easily detectable by scanning electron microscopy than by thin-section transmission electron microscopy. Therefore, scanning electron microscopy appears to be a useful and easy method for the study of knob distribution. Freeze-fracture and etching demonstrated that the knobs were protruded structures and were evenly distributed over the erythrocyte membrane. The P face of the infected, human RBC membrane showed evenly distributed intramembrane particles (IMP) and no aggregation or depletion of IMP could be observed over the erythrocyte membrane covering the knobs (Fig.
- Published
- 1983
404. Labeling of Sporozoites of Plasmodium berghei with Tritiated Purines
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Richard L. Jacobs, Louis C. Koontz, and Louis H. Miller
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Infectivity ,Biology ,biology.organism_classification ,Blood meal ,Virology ,Molecular biology ,Giemsa stain ,Hemocytometer ,In vivo ,Parasite hosting ,Parasitology ,Plasmodium berghei ,Anopheles stephensi ,Ecology, Evolution, Behavior and Systematics - Abstract
Sporozoites were labeled in vivo. Mosquitoes (Anopheles stephensi) infected with the NK-65 strain of P. berghei were allowed to feed ad lib. for 14 days subsequent to an infective blood meal on 5% Karo syrup solution containing different levels of tritium-labled purines and pyrimidines. Sporozoites were harvested on day 16 by dissection of mosquito salivary glands. Isotope incorporation in sporozoites was determined by autoradiography. Each of the purines tested, including adenine-8-3H, adenosine-3H (G), deoxyadenosine-3H (G), and deoxyguanosine-3H (G), was incorporated into both nuclear and cytoplasmic regions of sporozoites when fed to mosquitoes at 5 to 100 ,uCi/ml. Similar levels of the pyrimidines tested, including thymine-methyl-3H, thymidine-methyl-3H, or orotic-5-3H acid, failed to label sporozoites. The incorporation of preformed purines, but not pyrimidines, by developing sporozoites suggests that the parasite may require exogenous sources of purine during its development in the mosquito but relies on de novo synthesis of pyrimidines. The adenine8-3H-labeled sporozoites were shown to be infective by intravenous inoculation into A/J mice. These results demonstrate the feasibility of labeling developing sporozoites and should provide a means for further studies on the developmental cycle of malaria in the vertebrate host. After the discovery of exoerythrocytic bodies of malaria in the liver of monkeys and man (Shortt and Garnham, 1948) it was generally assumed that relapses were caused by a continual cycling of histiotrophic merozoites in the liver. More recently, Garnham (1967) has proposed that relapses may be caused by sporozoites which remain latent in parenchymal cells of the liver for various periods of time before undergoing development. To date, these latent forms have not been demonstrated, possibly because of their small size and similarity to the cytoplasm of liver cells in stained preparations. Radionuclide labeling of sporozoites would provide a means for recognizing these latent forms in tissue if, indeed, they exist. In the present study a method for labeling sporozoites in vivo with tritiated purines was developed. In addition, the labeled sporozoites were shown to retain their infectivity when inoculated into susceptible hosts. MATERIALS AND METHODS Anopheles stephensi mosquitoes were allowed to feed on hamsters infected with the NK-65 strain of Plasmodium berghei and maintained at Received for publication 18 September 1973. * This work was presented in part at the 57th Annual Meeting of the Federation of American Societies for Experimental Biology, Atlantic City, New Jersey (1973, Fed. Proc. 32: 704). 21 C as described by Yoeli et al. (1965). Subsequent to the infective blood meal, mosquitoes were allowed to feed from the mouth of a plastic dropping pipette that contained tritium-labeled purines or pyrimidines in 5% Karo syrup solution. The mouth of the pipette was mounted in contact with the mesh on top of the cage. Fresh isotope solution was supplied every other day for a period of 16 days. Sporozoites were harvested on day 18 by dissection of mosquito salivary glands into a 1:1 mixture of saline and mouse plasma. The glands were gently homogenized in a 3-ml tissue grinder fitted with a Teflon pestle in an ice bath. Sporozoite yield was estimated from counts in a Neubauer hemocytometer. Viability of adenine-8-3H-labeled sporozoites was evaluated by the intravenous inoculation of approximately 10,000 sporozoites into 6to 8-weekold A/J mice (Jackson Laboratories, Bar Harbor, Maine) within 1 hr after dissection of salivary glands. Infectivity and prepatent period were determined by daily Giemsa-stained blood films. Isotope incorporation by sporozoites was determined by autoradiography using Kodak NTB-2 nuclear track emulsion (Eastman Kodak Co.). Infected salivary glands were crushed with a glass cover slip on slides previously coated by dipping in 1% bovine serum albumin. Sporozoites were then fixed with methanol and allowed to air-dry. Slides were coated by dipping into undiluted photographic emulsion at 40 C. After exposure to the emulsion for various intervals at 4 C, slides were processed with Kodak D-19 developer and fixer. The preparation was then stained through the emulsion with 7.5% Giemsa for 1 hr at pH 7.2. The degree of labeling was determined microscopically under oil immersion by counting silver grains associated with individual sporozoites.
- Published
- 1974
405. Immunogenic Antigens Common to Plasmodium knowlesi and Plasmodium falciparum Are Expressed on the Surface of Infected Erythrocytes
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Louis H. Miller, Donald F. H. Wallach, Rupert Schmidt-Ullrich, and John Lightholder
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Plasmodium falciparum ,Immunogenetics ,Biology ,medicine.disease_cause ,biology.organism_classification ,Virology ,Plasmodium ,Microbiology ,Schizogony ,Immune system ,Antigen ,Staphylococcus aureus ,Plasmodium knowlesi ,parasitic diseases ,medicine ,Parasitology ,Ecology, Evolution, Behavior and Systematics - Abstract
Sera of Gambian individuals and rhesus monkeys immune against infections with Plasmo- dium falciparum and Plasmodium knowlesi, respectively, were reacted with Triton X-100-solubilized membranes of infected erythrocytes. Indirect immune precipitation with Staphylococcus aureus, Cowan strain A, followed by dodecylsulfate-polyacrylamide gel electrophoresis, were used to identify interspecies plasmodial antigens that were immunogenic in vivo. Both types of sera specifically precipitated Plasmo- dium-specific antigens with MrS of 125,000, 90,000, and 65,000 to 50,000 from membranes of P. knowlesi- infected erythrocytes that had been labeled with 125I using the lactoperoxidase-catalyzed radioiodination or metabolically with "4C-amino acids. In addition, P. falciparum inhibited the precipitation of P. knowlesi antigens by the Gambian immune sera. Our results indicate, that during erythrocytic schizogony, inter- species Plasmodium antigens are exposed on the surfaces of infected erythrocytes.
- Published
- 1982
406. Continuous In-vitro Cultivation of the Human Malaria Parasite
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Louis H. Miller
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medicine.medical_specialty ,business.industry ,Plasmodium falciparum ,Vaccination ,General Medicine ,medicine.disease ,Malaria ,Work (electrical) ,Internal Medicine ,medicine ,Humans ,Parasite hosting ,Intensive care medicine ,business - Abstract
Excerpt Sometimes an advance in biomedical research deserves to be highlighted in a clinical journal even though the work does not have immediate application to the practice of medicine. One such a...
- Published
- 1978
407. Transfusion Malaria and Immigrant Blood Donors
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Louis H. Miller
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Hepatitis ,Pediatrics ,medicine.medical_specialty ,biology ,Donor selection ,business.industry ,Incidence (epidemiology) ,Parasitemia ,Plasmodium malariae ,medicine.disease ,biology.organism_classification ,Asymptomatic ,Infectious Diseases ,parasitic diseases ,Immunology ,medicine ,Immunology and Allergy ,medicine.symptom ,business ,Direct fluorescent antibody ,Malaria - Abstract
reported in the literature [3]. Unlike other species of Plasmodium that cause malaria, which are usually eliminated in less than three years, P. malariae persists in the blood for many years [3, 4]. Asexual erythrocytic parasites, which have a 72hr cycle, evade the immune system for years by unknown mechanisms. Because of low parasitemia, parasites are usually not seen on thick or thin blood films, and the chronically infected individual is usually asymptomatic. After a case of transfusion malaria occurs, the infected donor is identified by the indirect fluorescent antibody test. In 1974, the American Association of Blood Banks and the American National Red Cross changed the standards for donor selection (for a detailed discussion, see [4]). For the first time immigrants from endemic areas could be accepted as blood donors if they had been out of an endemic area for three years and had been asymptomatic in the interim. It might be expected that this change in the regulations would increase the incidence of transfusion malaria due to P. malariae, since malaria caused by P. malariae is characterized by a chronic, asymptomatic erythrocytic infection [3, 4]. However, P. malariae rarely causes serious morbidity or death. A few cases per year of transfusion malaria caused by this nonmalignant malaria parasite may be acceptable in order to maintain an adequate supply of highquality blood (e.g., blood with a lower risk for hepatitis). Whatever the reasons for the change, rules for donor selection should be reevaluated
- Published
- 1976
408. Transmission of Three Strains of Plasmodium falciparum from Monkey to Man
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William E. Collins, Louis H. Miller, David J. Wyler, Richard H. Glew, William A. Howard, and Peter G. Contacos
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medicine.medical_specialty ,biology ,Plasmodium vivax ,Anopheles ,Plasmodium falciparum ,medicine.disease ,biology.organism_classification ,Virology ,Parasitology ,Anopheles albimanus ,parasitic diseases ,Tropical medicine ,medicine ,Aotus trivirgatus ,Ecology, Evolution, Behavior and Systematics ,Malaria - Abstract
Infections of 3 different strains of Plasmodium falciparum in the Aotus trivirgatus monkey were shown to be infectious to 6 different species of Anopheles. The A. freeborni were more readily infected. Transmission of the infection to 20 men was obtained by the bites of infected A. freeborni mosquitoes after extrinsic incubation periods of 13 to 26 days. The prepatent periods in the men ranged from 9 to 13 days with a mean of 11.2 days. It has been reported previously that human malaria in the Aotus trivirgatus monkey is infectious to mosquitoes and that the infections can be subsequently transmitted back to man. Five different strains of Plasmodium vivax, all from Central America, have been transmitted from these monkeys to man via the bites of infected Anopheles albimanus and A. freeborni mosquitoes (Young et al., 1966; Collins et al., 1972). Previously, we had reported the successful transmission of the Malayan IV strain of P. falciparum to two human volunteers (Contacos and Collins, 1968; Collins et al., 1968). Reported here are the results of additional studies on the transmission of three strains of P. falciparum from Aotus monkey to man. MATERIALS AND METHODS The 3 strains of P. falciparum used were (1) the Malayan IV which was isolated from a Peace Corps volunteer who contracted the infection while working in the Central Perak area of Peninsula Malaysia (Chin et al., 1966), (2) the Cambodian I which was isolated from an American parasitologist who contracted the infection while working in the Paillin District of Western Cambodia (Eyles et al., 1963), and (3) the Panama II which was isolated from an 11-year-old Panamanian national residing on the Atlantic side of the Republic of Panama (Collins et al., 1973). The Malayan IV and the Panama II strains have been shown to have some degree of resistance to Received for publication 14 May 1973. * National Institutes of Health, LPD, Building 5, Room 114, Bethesda, Maryland 20014. t Center for Disease Control, Malaria Program, 1600 Clifton Road, Atlanta, Georgia 30333. Mayo Clinic, 4023-18th Avenue, N.W., Rochester, Minnesota 55901. chloroquine. The Cambodian I strain is sensitive to this drug. Aotus trivirgatus monkeys, obtained commercially, had their origin in Colombia, South America. Prior serologic and parasitologic examination indicated that the animals were free of natural malarial infection. The A. freeborni mosquitoes were the F-l strain originally isolated from Marysville, California (Hardman, 1947) and maintained in our laboratory since 1944. The A. maculatus were obtained from the Institute for Medical Research, Kuala Lumpur, Malaysia (Ow Yang et al., 1963) in 1964 and maintained in our laboratory since then. The A. quadrimaculatus were the Q-1 strain which was obtained from Technical Development Laboratories, CDC, Savannah, Georgia, and maintained in our laboratory since 1959. The A. stephensi were from Delhi, India, and were obtained from the London School of Hygiene and Tropical Medicine, London, England, in 1963. The A. balabacensis balabacensis were originally from Thailand and obtained from the Walter Reed Army Institute of Research, Washington, D. C. (Esah and Scanlon, 1966). Three strains of A. albimanus were examined. Two, the Apastepeque and the Melara strains, were established in El Salvador by the Central America Malaria Research Station, CDC, San Salvador, El Salvador; we obtained the colonies from them in 1971. The other strain of A. albimanus was the A-1 strain from Panama which was obtained from the Gorgas Memorial Laboratory in 1972. This study was performed in prisoner volunteers at the Atlanta Federal Penitentiary as part of a research program on evaluation of antimalarial drugs. The technique used for the feedings on the monkeys and on the human volunteers are those previously reported (Collins et al., 1968).
- Published
- 1973
409. Visualization of Red Cell Membranes of Lysed Malaria-Infected Cells by Differential Interference Microscopy
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Louis H. Miller and James A. Dvorak
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Lysis ,biology ,Red Cell ,Haplorhini ,biology.organism_classification ,medicine.disease ,Interference microscopy ,Cell biology ,Cell membrane ,Membrane ,medicine.anatomical_structure ,Microscopy ,medicine ,Parasitology ,Ecology, Evolution, Behavior and Systematics ,Malaria - Published
- 1973
410. Acute Renal Failure in Plasmodium falciparum Malaria
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Philip Eichler, Peter J. Bartelloni, Louis H. Miller, Kevin G. Barry, and Craig J. Canfield
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Creatinine ,medicine.medical_specialty ,Quinine ,biology ,business.industry ,medicine.medical_treatment ,Acute kidney injury ,Plasmodium falciparum ,biology.organism_classification ,medicine.disease ,Haemolysis ,Gastroenterology ,Surgery ,Peritoneal dialysis ,chemistry.chemical_compound ,chemistry ,Internal medicine ,parasitic diseases ,Internal Medicine ,Medicine ,Hemodialysis ,business ,Malaria ,medicine.drug - Abstract
Two patients with renal failure due to heavy infection with Plasmodium falciparum were successfully treated by peritoneal dialysis. Rapid clinical deterioration precluded safe transfer to a hemodialysis facility. The efficiency of peritoneal dialysis, although less than in other forms of renal failure, was sufficient to control the clinical and biochemical manifestations of renal failure. Quinine in combination with other antimalarial drugs was successful in doses less than usually employed for the chloroquine-resistant species of southeast Asia. No accumulation of quinine occurred in the one patient studied. However, a reduced dosage should be employed under these circumstances.
- Published
- 1968
411. Whole genome sequencing of Plasmodium vivax isolates reveals frequent sequence and structural polymorphisms in erythrocyte binding genes.
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Anthony Ford, Daniel Kepple, Beka Raya Abagero, Jordan Connors, Richard Pearson, Sarah Auburn, Sisay Getachew, Colby Ford, Karthigayan Gunalan, Louis H Miller, Daniel A Janies, Julian C Rayner, Guiyun Yan, Delenasaw Yewhalaw, and Eugenia Lo
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Arctic medicine. Tropical medicine ,RC955-962 ,Public aspects of medicine ,RA1-1270 - Abstract
Plasmodium vivax malaria is much less common in Africa than the rest of the world because the parasite relies primarily on the Duffy antigen/chemokine receptor (DARC) to invade human erythrocytes, and the majority of Africans are Duffy negative. Recently, there has been a dramatic increase in the reporting of P. vivax cases in Africa, with a high number of them being in Duffy negative individuals, potentially indicating P. vivax has evolved an alternative invasion mechanism that can overcome Duffy negativity. Here, we analyzed single nucleotide polymorphism (SNP) and copy number variation (CNV) in Whole Genome Sequence (WGS) data from 44 P. vivax samples isolated from symptomatic malaria patients in southwestern Ethiopia, where both Duffy positive and Duffy negative individuals are found. A total of 123,711 SNPs were detected, of which 22.7% were nonsynonymous and 77.3% were synonymous mutations. The largest number of SNPs were detected on chromosomes 9 (24,007 SNPs; 19.4% of total) and 10 (16,852 SNPs, 13.6% of total). There were particularly high levels of polymorphism in erythrocyte binding gene candidates including merozoite surface protein 1 (MSP1) and merozoite surface protein 3 (MSP3.5, MSP3.85 and MSP3.9). Two genes, MAEBL and MSP3.8 related to immunogenicity and erythrocyte binding function were detected with significant signals of positive selection. Variation in gene copy number was also concentrated in genes involved in host-parasite interactions, including the expansion of the Duffy binding protein gene (PvDBP) on chromosome 6 and MSP3.11 on chromosome 10. Based on the phylogeny constructed from the whole genome sequences, the expansion of these genes was an independent process among the P. vivax lineages in Ethiopia. We further inferred transmission patterns of P. vivax infections among study sites and showed various levels of gene flow at a small geographical scale. The genomic features of P. vivax provided baseline data for future comparison with those in Duffy-negative individuals and allowed us to develop a panel of informative Single Nucleotide Polymorphic markers diagnostic at a micro-geographical scale.
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- 2020
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412. The Plasmodium falciparum rhoptry bulb protein RAMA plays an essential role in rhoptry neck morphogenesis and host red blood cell invasion.
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Emma S Sherling, Abigail J Perrin, Ellen Knuepfer, Matthew R G Russell, Lucy M Collinson, Louis H Miller, and Michael J Blackman
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Immunologic diseases. Allergy ,RC581-607 ,Biology (General) ,QH301-705.5 - Abstract
The malaria parasite Plasmodium falciparum invades, replicates within and destroys red blood cells in an asexual blood stage life cycle that is responsible for clinical disease and crucial for parasite propagation. Invasive malaria merozoites possess a characteristic apical complex of secretory organelles that are discharged in a tightly controlled and highly regulated order during merozoite egress and host cell invasion. The most prominent of these organelles, the rhoptries, are twinned, club-shaped structures with a body or bulb region that tapers to a narrow neck as it meets the apical prominence of the merozoite. Different protein populations localise to the rhoptry bulb and neck, but the function of many of these proteins and how they are spatially segregated within the rhoptries is unknown. Using conditional disruption of the gene encoding the only known glycolipid-anchored malarial rhoptry bulb protein, rhoptry-associated membrane antigen (RAMA), we demonstrate that RAMA is indispensable for blood stage parasite survival. Contrary to previous suggestions, RAMA is not required for trafficking of all rhoptry bulb proteins. Instead, RAMA-null parasites display selective mislocalisation of a subset of rhoptry bulb and neck proteins (RONs) and produce dysmorphic rhoptries that lack a distinct neck region. The mutant parasites undergo normal intracellular development and egress but display a fatal defect in invasion and do not induce echinocytosis in target red blood cells. Our results indicate that distinct pathways regulate biogenesis of the two main rhoptry sub-compartments in the malaria parasite.
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- 2019
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413. Frequent expansion of Plasmodium vivax Duffy Binding Protein in Ethiopia and its epidemiological significance.
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Eugenia Lo, Jessica B Hostetler, Delenasaw Yewhalaw, Richard D Pearson, Muzamil M A Hamid, Karthigayan Gunalan, Daniel Kepple, Anthony Ford, Daniel A Janies, Julian C Rayner, Louis H Miller, and Guiyun Yan
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Arctic medicine. Tropical medicine ,RC955-962 ,Public aspects of medicine ,RA1-1270 - Abstract
Plasmodium vivax invasion of human erythrocytes depends on the Duffy Binding Protein (PvDBP) which interacts with the Duffy antigen. PvDBP copy number has been recently shown to vary between P. vivax isolates in Sub-Saharan Africa. However, the extent of PvDBP copy number variation, the type of PvDBP multiplications, as well as its significance across broad samples are still unclear. We determined the prevalence and type of PvDBP duplications, as well as PvDBP copy number variation among 178 Ethiopian P. vivax isolates using a PCR-based diagnostic method, a novel quantitative real-time PCR assay and whole genome sequencing. For the 145 symptomatic samples, PvDBP duplications were detected in 95 isolates, of which 81 had the Cambodian and 14 Malagasy-type PvDBP duplications. PvDBP varied from 1 to >4 copies. Isolates with multiple PvDBP copies were found to be higher in symptomatic than asymptomatic infections. For the 33 asymptomatic samples, PvDBP was detected with two copies in two of the isolates, and both were the Cambodian-type PvDBP duplication. PvDBP copy number in Duffy-negative heterozygotes was not significantly different from that in Duffy-positives, providing no support for the hypothesis that increased copy number is a specific association with Duffy-negativity, although the number of Duffy-negatives was small and further sampling is required to test this association thoroughly.
- Published
- 2019
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414. NK cells inhibit Plasmodium falciparum growth in red blood cells via antibody-dependent cellular cytotoxicity
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Gunjan Arora, Geoffrey T Hart, Javier Manzella-Lapeira, Justin YA Doritchamou, David L Narum, L Michael Thomas, Joseph Brzostowski, Sumati Rajagopalan, Ogobara K Doumbo, Boubacar Traore, Louis H Miller, Susan K Pierce, Patrick E Duffy, Peter D Crompton, Sanjay A Desai, and Eric O Long
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Human ,P.falciparum ,ADCC ,NK ,RBC ,Medicine ,Science ,Biology (General) ,QH301-705.5 - Abstract
Antibodies acquired naturally through repeated exposure to Plasmodium falciparum are essential in the control of blood-stage malaria. Antibody-dependent functions may include neutralization of parasite–host interactions, complement activation, and activation of Fc receptor functions. A role of antibody-dependent cellular cytotoxicity (ADCC) by natural killer (NK) cells in protection from malaria has not been established. Here we show that IgG isolated from adults living in a malaria-endemic region activated ADCC by primary human NK cells, which lysed infected red blood cells (RBCs) and inhibited parasite growth in an in vitro assay for ADCC-dependent growth inhibition. RBC lysis by NK cells was highly selective for infected RBCs in a mixed culture with uninfected RBCs. Human antibodies to P. falciparum antigens PfEMP1 and RIFIN were sufficient to promote NK-dependent growth inhibition. As these results implicate acquired immunity through NK-mediated ADCC, antibody-based vaccines that target bloodstream parasites should consider this new mechanism of action.
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- 2018
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415. The Plasmodium falciparum rhoptry protein RhopH3 plays essential roles in host cell invasion and nutrient uptake
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Emma S Sherling, Ellen Knuepfer, Joseph A Brzostowski, Louis H Miller, Michael J Blackman, and Christiaan van Ooij
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Malaria ,pathogenesis ,Plasmodium ,Medicine ,Science ,Biology (General) ,QH301-705.5 - Abstract
Merozoites of the protozoan parasite responsible for the most virulent form of malaria, Plasmodium falciparum, invade erythrocytes. Invasion involves discharge of rhoptries, specialized secretory organelles. Once intracellular, parasites induce increased nutrient uptake by generating new permeability pathways (NPP) including a Plasmodium surface anion channel (PSAC). RhopH1/Clag3, one member of the three-protein RhopH complex, is important for PSAC/NPP activity. However, the roles of the other members of the RhopH complex in PSAC/NPP establishment are unknown and it is unclear whether any of the RhopH proteins play a role in invasion. Here we demonstrate that RhopH3, the smallest component of the complex, is essential for parasite survival. Conditional truncation of RhopH3 substantially reduces invasive capacity. Those mutant parasites that do invade are defective in nutrient import and die. Our results identify a dual role for RhopH3 that links erythrocyte invasion to formation of the PSAC/NPP essential for parasite survival within host erythrocytes.
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- 2017
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416. An impossible journey? The development of Plasmodium falciparum NF54 in Culex quinquefasciatus.
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Julia Knöckel, Alvaro Molina-Cruz, Elizabeth Fischer, Olga Muratova, Ashley Haile, Carolina Barillas-Mury, and Louis H Miller
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Medicine ,Science - Abstract
Although Anopheles mosquitoes are the vectors for human Plasmodium spp., there are also other mosquito species-among them culicines (Culex spp., Aedes spp.)-present in malaria-endemic areas. Culicine mosquitoes transmit arboviruses and filarial worms to humans and are vectors for avian Plasmodium spp., but have never been observed to transmit human Plasmodium spp. When ingested by a culicine mosquito, parasites could either face an environment that does not allow development due to biologic incompatibility or be actively killed by the mosquito's immune system. In the latter case, the molecular mechanism of killing must be sufficiently powerful that Plasmodium is not able to overcome it. To investigate how human malaria parasites develop in culicine mosquitoes, we infected Culex quinquefasciatus with Plasmodium falciparum NF54 and monitored development of parasites in the blood bolus and midgut epithelium at different time points. Our results reveal that ookinetes develop in the midgut lumen of C. quinquefasciatus in slightly lower numbers than in Anopheles gambiae G3. After 30 hours, parasites have invaded the midgut and can be observed on the basal side of the midgut epithelium by confocal and transmission electron microscopy. Very few of the parasites in C. quinquefasciatus are alive, most of them are lysed. Eight days after the mosquito's blood meal, no oocysts can be found in C. quinquefasciatus. Our results suggest that the mosquito immune system could be involved in parasite killing early in development after ookinetes have crossed the midgut epithelium and come in contact with the mosquito hemolymph.
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- 2013
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417. Immunogenicity of self-associated aggregates and chemically cross-linked conjugates of the 42 kDa Plasmodium falciparum merozoite surface protein-1.
- Author
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Feng Qian, Karine Reiter, Yanling Zhang, Richard L Shimp, Vu Nguyen, Joan A Aebig, Kelly M Rausch, Daming Zhu, Lynn Lambert, Gregory E D Mullen, Laura B Martin, Carole A Long, Louis H Miller, and David L Narum
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Medicine ,Science - Abstract
Self-associated protein aggregates or cross-linked protein conjugates are, in general, more immunogenic than oligomeric or monomeric forms. In particular, the immunogenicity in mice of a recombinant malaria transmission blocking vaccine candidate, the ookinete specific Plasmodium falciparum 25 kDa protein (Pfs25), was increased more than 1000-fold when evaluated as a chemical cross-linked protein-protein conjugate as compared to a formulated monomer. Whether alternative approaches using protein complexes improve the immunogenicity of other recombinant malaria vaccine candidates is worth assessing. In this work, the immunogenicity of the recombinant 42 kDa processed form of the P. falciparum merozoite surface protein 1 (MSP1(42)) was evaluated as a self-associated, non-covalent aggregate and as a chemical cross-linked protein-protein conjugate to ExoProtein A, which is a recombinant detoxified form of Pseudomonas aeruginosa exotoxin A. MSP1(42) conjugates were prepared and characterized biochemically and biophysically to determine their molar mass in solution and stoichiometry, when relevant. The immunogenicity of the MSP1(42) self-associated aggregates, cross-linked chemical conjugates and monomers were compared in BALB/c mice after adsorption to aluminum hydroxide adjuvant, and in one instance in association with the TLR9 agonist CPG7909 with an aluminum hydroxide formulation. Antibody titers were assessed by ELISA. Unlike observations made for Pfs25, no significant enhancement in MSP1(42) specific antibody titers was observed for any conjugate as compared to the formulated monomer or dimer, except for the addition of the TLR9 agonist CPG7909. Clearly, enhancing the immunogenicity of a recombinant protein vaccine candidate by the formation of protein complexes must be established on an empirical basis.
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- 2012
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418. Non-apical membrane antigen 1 (AMA1) IgGs from Malian children interfere with functional activity of AMA1 IgGs as judged by growth inhibition assay.
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Kazutoyo Miura, Suwani Perera, Sarah Brockley, Hong Zhou, Joan A Aebig, Samuel E Moretz, Louis H Miller, Ogobara K Doumbo, Issaka Sagara, Alassane Dicko, Ruth D Ellis, and Carole A Long
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Medicine ,Science - Abstract
Apical membrane antigen 1 (AMA1) is one of the best-studied blood-stage malaria vaccine candidates. When an AMA1 vaccine was tested in a malaria naïve population, it induced functionally active antibodies judged by Growth Inhibition Assay (GIA). However, the same vaccine failed to induce higher growth-inhibitory activity in adults living in a malaria endemic area. Vaccination did induce functionally active antibodies in malaria-exposed children with less than 20% inhibition in GIA at baseline, but not in children with more than that level of baseline inhibition.Total IgGs were purified from plasmas collected from the pediatric trial before and after immunization and pools of total IgGs were made. Another set of total IgGs was purified from U.S. adults immunized with AMA1 (US-total IgG). From these total IgGs, AMA1-specific and non-AMA1 IgGs were affinity purified and the functional activity of these IgGs was evaluated by GIA. Competition ELISA was performed with the U.S.-total IgG and non-AMA1 IgGs from malaria-exposed children.AMA1-specific IgGs from malaria-exposed children and U.S. vaccinees showed similar growth-inhibitory activity at the same concentrations. When mixed with U.S.-total IgG, non-AMA1 IgGs from children showed an interference effect in GIA. Interestingly, the interference effect was higher with non-AMA1 IgGs from higher titer pools. The non-AMA1 IgGs did not compete with anti-AMA1 antibody in U.S.-total IgG in the competition ELISA.Children living in a malaria endemic area have a fraction of IgGs that interferes with the biological activity of anti-AMA1 antibody as judged by GIA. While the mechanism of interference is not resolved in this study, these results suggest it is not caused by direct competition between non-AMA1 IgG and AMA1 protein. This study indicates that anti-malaria IgGs induced by natural exposure may interfere with the biological effect of antibody induced by an AMA1-based vaccine in the target population.
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- 2011
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419. The Plasmodium falciparum-specific human memory B cell compartment expands gradually with repeated malaria infections.
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Greta E Weiss, Boubacar Traore, Kassoum Kayentao, Aissata Ongoiba, Safiatou Doumbo, Didier Doumtabe, Younoussou Kone, Seydou Dia, Agnes Guindo, Abdramane Traore, Chiung-Yu Huang, Kazutoyo Miura, Marko Mircetic, Shanping Li, Amy Baughman, David L Narum, Louis H Miller, Ogobara K Doumbo, Susan K Pierce, and Peter D Crompton
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Immunologic diseases. Allergy ,RC581-607 ,Biology (General) ,QH301-705.5 - Abstract
Immunity to Plasmodium falciparum (Pf) malaria is only acquired after years of repeated infections and wanes rapidly without ongoing parasite exposure. Antibodies are central to malaria immunity, yet little is known about the B-cell biology that underlies the inefficient acquisition of Pf-specific humoral immunity. This year-long prospective study in Mali of 185 individuals aged 2 to 25 years shows that Pf-specific memory B-cells and antibodies are acquired gradually in a stepwise fashion over years of repeated Pf exposure. Both Pf-specific memory B cells and antibody titers increased after acute malaria and then, after six months of decreased Pf exposure, contracted to a point slightly higher than pre-infection levels. This inefficient, stepwise expansion of both the Pf-specific memory B-cell and long-lived antibody compartments depends on Pf exposure rather than age, based on the comparator response to tetanus vaccination that was efficient and stable. These observations lend new insights into the cellular basis of the delayed acquisition of malaria immunity.
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- 2010
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420. Phase 1 trial of the Plasmodium falciparum blood stage vaccine MSP1(42)-C1/Alhydrogel with and without CPG 7909 in malaria naïve adults.
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Ruth D Ellis, Laura B Martin, Donna Shaffer, Carole A Long, Kazutoyo Miura, Michael P Fay, David L Narum, Daming Zhu, Gregory E D Mullen, Siddhartha Mahanty, Louis H Miller, and Anna P Durbin
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Medicine ,Science - Abstract
Merozoite surface protein 1(42) (MSP1(42)) is a leading blood stage malaria vaccine candidate. In order to induce immune responses that cover the major antigenic polymorphisms, FVO and 3D7 recombinant proteins of MSP1(42) were mixed (MSP1(42)-C1). To improve the level of antibody response, MSP1(42)-C1 was formulated with Alhydrogel plus the novel adjuvant CPG 7909.A Phase 1 clinical trial was conducted in healthy malaria-naïve adults at the Center for Immunization Research in Washington, D.C., to evaluate the safety and immunogenicity of MSP1(42)-C1/Alhydrogel +/- CPG 7909. Sixty volunteers were enrolled in dose escalating cohorts and randomized to receive three vaccinations of either 40 or 160 microg protein adsorbed to Alhydrogel +/- 560 microg CPG 7909 at 0, 1 and 2 months.Vaccinations were well tolerated, with only one related adverse event graded as severe (Grade 3 injection site erythema) and all other vaccine related adverse events graded as either mild or moderate. Local adverse events were more frequent and severe in the groups receiving CPG. The addition of CPG enhanced anti-MSP1(42) antibody responses following vaccination by up to 49-fold two weeks after second immunization and 8-fold two weeks after the third immunization when compared to MSP1(42)-C1/Alhydrogel alone (p
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- 2010
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421. From Tucson to genomics and transgenics: the vector biology network and the emergence of modern vector biology.
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Barry J Beaty, Denis J Prager, Anthony A James, Marcelo Jacobs-Lorena, Louis H Miller, John H Law, Frank H Collins, and Fotis C Kafatos
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Arctic medicine. Tropical medicine ,RC955-962 ,Public aspects of medicine ,RA1-1270 - Published
- 2009
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422. The cysteine-rich interdomain region from the highly variable plasmodium falciparum erythrocyte membrane protein-1 exhibits a conserved structure.
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Michael M Klein, Apostolos G Gittis, Hua-Poo Su, Morris O Makobongo, Jaime M Moore, Sanjay Singh, Louis H Miller, and David N Garboczi
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Immunologic diseases. Allergy ,RC581-607 ,Biology (General) ,QH301-705.5 - Abstract
Plasmodium falciparum malaria parasites, living in red blood cells, express proteins of the erythrocyte membrane protein-1 (PfEMP1) family on the red blood cell surface. The binding of PfEMP1 molecules to human cell surface receptors mediates the adherence of infected red blood cells to human tissues. The sequences of the 60 PfEMP1 genes in each parasite genome vary greatly from parasite to parasite, yet the variant PfEMP1 proteins maintain receptor binding. Almost all parasites isolated directly from patients bind the human CD36 receptor. Of the several kinds of highly polymorphic cysteine-rich interdomain region (CIDR) domains classified by sequence, only the CIDR1alpha domains bind CD36. Here we describe the CD36-binding portion of a CIDR1alpha domain, MC179, as a bundle of three alpha-helices that are connected by a loop and three additional helices. The MC179 structure, containing seven conserved cysteines and 10 conserved hydrophobic residues, predicts similar structures for the hundreds of CIDR sequences from the many genome sequences now known. Comparison of MC179 with the CIDR domains in the genome of the P. falciparum 3D7 strain provides insights into CIDR domain structure. The CIDR1alpha three-helix bundle exhibits less than 20% sequence identity with the three-helix bundles of Duffy-binding like (DBL) domains, but the two kinds of bundles are almost identical. Despite the enormous diversity of PfEMP1 sequences, the CIDR1alpha and DBL protein structures, taken together, predict that a PfEMP1 molecule is a polymer of three-helix bundles elaborated by a variety of connecting helices and loops. From the structures also comes the insight that DBL1alpha domains are approximately 100 residues larger and that CIDR1alpha domains are approximately 100 residues smaller than sequence alignments predict. This new understanding of PfEMP1 structure will allow the use of better-defined PfEMP1 domains for functional studies, for the design of candidate vaccines, and for understanding the molecular basis of cytoadherence.
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- 2008
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423. Phase 1 trial of AMA1-C1/Alhydrogel plus CPG 7909: an asexual blood-stage vaccine for Plasmodium falciparum malaria.
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Gregory E D Mullen, Ruth D Ellis, Kazutoyo Miura, Elissa Malkin, Caroline Nolan, Mhorag Hay, Michael P Fay, Allan Saul, Daming Zhu, Kelly Rausch, Samuel Moretz, Hong Zhou, Carole A Long, Louis H Miller, and John Treanor
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Medicine ,Science - Abstract
Apical Membrane Antigen 1 (AMA1), a polymorphic merozoite surface protein, is a leading blood-stage malaria vaccine candidate. This is the first reported use in humans of an investigational vaccine, AMA1-C1/Alhydrogel, with the novel adjuvant CPG 7909.A phase 1 trial was conducted at the University of Rochester with 75 malaria-naive volunteers to assess the safety and immunogenicity of the AMA1-C1/Alhydrogel+CPG 7909 malaria vaccine. Participants were sequentially enrolled and randomized within dose escalating cohorts to receive three vaccinations on days 0, 28 and 56 of either 20 microg of AMA1-C1/Alhydrogel+564 microg CPG 7909 (n = 15), 80 microg of AMA1-C1/Alhydrogel (n = 30), or 80 microg of AMA1-C1/Alhydrogel+564 microg CPG 7909 (n = 30).Local and systemic adverse events were significantly more likely to be of higher severity with the addition of CPG 7909. Anti-AMA1 immunoglobulin G (IgG) were detected by enzyme-linked immunosorbent assay (ELISA), and the immune sera of volunteers that received 20 microg or 80 microg of AMA1-C1/Alhydrogel+CPG 7909 had up to 14 fold significant increases in anti-AMA1 antibody concentration compared to 80 microg of AMA1-C1/Alhydrogel alone. The addition of CPG 7909 to the AMA1-C1/Alhydrogel vaccine in humans also elicited AMA1 specific immune IgG that significantly and dramatically increased the in vitro growth inhibition of homologous parasites to levels as high as 96% inhibition.The safety profile of the AMA1-C1/Alhydrogel+CPG 7909 malaria vaccine is acceptable, given the significant increase in immunogenicity observed. Further clinical development is ongoing.ClinicalTrials.gov NCT00344539.
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- 2008
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424. Phase 1 trial of malaria transmission blocking vaccine candidates Pfs25 and Pvs25 formulated with montanide ISA 51.
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Yimin Wu, Ruth D Ellis, Donna Shaffer, Erica Fontes, Elissa M Malkin, Siddhartha Mahanty, Michael P Fay, David Narum, Kelly Rausch, Aaron P Miles, Joan Aebig, Andrew Orcutt, Olga Muratova, Guanhong Song, Lynn Lambert, Daming Zhu, Kazutoyo Miura, Carole Long, Allan Saul, Louis H Miller, and Anna P Durbin
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Medicine ,Science - Abstract
BackgroundPfs25 and Pvs25, surface proteins of mosquito stage of the malaria parasites P. falciparum and P. vivax, respectively, are leading candidates for vaccines preventing malaria transmission by mosquitoes. This single blinded, dose escalating, controlled Phase 1 study assessed the safety and immunogenicity of recombinant Pfs25 and Pvs25 formulated with Montanide ISA 51, a water-in-oil emulsion.Methodology/principal findingsThe trial was conducted at The Johns Hopkins Center for Immunization Research, Washington DC, USA, between May 16, 2005-April 30, 2007. The trial was designed to enroll 72 healthy male and non-pregnant female volunteers into 1 group to receive adjuvant control and 6 groups to receive escalating doses of the vaccines. Due to unexpected reactogenicity, the vaccination was halted and only 36 volunteers were enrolled into 4 groups: 3 groups of 10 volunteers each were immunized with 5 microg of Pfs25/ISA 51, 5 microg of Pvs25/ISA 51, or 20 microg of Pvs25/ISA 51, respectively. A fourth group of 6 volunteers received adjuvant control (PBS/ISA 51). Frequent local reactogenicity was observed. Systemic adverse events included two cases of erythema nodosum considered to be probably related to the combination of the antigen and the adjuvant. Significant antibody responses were detected in volunteers who completed the lowest scheduled doses of Pfs25/ISA 51. Serum anti-Pfs25 levels correlated with transmission blocking activity.Conclusion/significanceIt is feasible to induce transmission blocking immunity in humans using the Pfs25/ISA 51 vaccine, but these vaccines are unexpectedly reactogenic for further development. This is the first report that the formulation is associated with systemic adverse events including erythema nodosum.Trial registrationClinicalTrials.gov NCT00295581.
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- 2008
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425. Phase 1 study of a combination AMA1 blood stage malaria vaccine in Malian children.
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Alassane Dicko, Issaka Sagara, Ruth D Ellis, Kazutoyo Miura, Ousmane Guindo, Beh Kamate, Moussa Sogoba, Mohamed Balla Niambelé, Mady Sissoko, Mounirou Baby, Amagana Dolo, Gregory E D Mullen, Michael P Fay, Mark Pierce, Dapa A Diallo, Allan Saul, Louis H Miller, and Ogobara K Doumbo
- Subjects
Medicine ,Science - Abstract
Apical Membrane Antigen-1 (AMA1) is one of the leading blood stage malaria vaccine candidates. AMA1-C1/Alhydrogel consists of an equal mixture of recombinant AMA1 from FVO and 3D7 clones of P. falciparum, adsorbed onto Alhydrogel. A Phase 1 study in semi-immune adults in Mali showed that the vaccine was safe and immunogenic, with higher antibody responses in those who received the 80 microg dose. The aim of this study was to assess the safety and immunogenicity of this vaccine in young children in a malaria endemic area.This was a Phase 1 dose escalating study in 36 healthy children aged 2-3 years started in March 2006 in Donéguébougou, Mali. Eighteen children in the first cohort were randomized 2 ratio 1 to receive either 20 microg AMA1-C1/Alhydrogel or Haemophilus influenzae type b Hiberix vaccine. Two weeks later 18 children in the second cohort were randomized 2 ratio 1 to receive either 80 microg AMA1-C1/Alhydrogel or Haemophilus influenzae type b Hiberix vaccine. Vaccinations were administered on Days 0 and 28 and participants were examined on Days 1, 2, 3, 7, and 14 after vaccination and then about every two months. Results to Day 154 are reported in this manuscript.Of 36 volunteers enrolled, 33 received both vaccinations. There were 9 adverse events related to the vaccination in subjects who received AMA1-C1 vaccine and 7 in those who received Hiberix. All were mild to moderate. No vaccine-related serious or grade 3 adverse events were observed. There was no increase in adverse events with increasing dose of vaccine or number of immunizations. In subjects who received the test vaccine, antibodies to AMA1 increased on Day 14 and peaked at Day 42, with changes from baseline significantly different from subjects who received control vaccine.AMA-C1 vaccine is well tolerated and immunogenic in children in this endemic area although the antibody response was short lived.Clinicaltrials.gov NCT00341250.
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- 2008
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426. Impact of a Plasmodium falciparum AMA1 vaccine on antibody responses in adult Malians.
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Alassane Dicko, David J Diemert, Issaka Sagara, Moussa Sogoba, Mohamed B Niambele, Mahamadoun H Assadou, Ousmane Guindo, Beh Kamate, Mounirou Baby, Mady Sissoko, Elissa M Malkin, Michael P Fay, Mahamadou A Thera, Kazutoyo Miura, Amagana Dolo, Dapa A Diallo, Gregory E Mullen, Carole A Long, Allan Saul, Ogobara Doumbo, and Louis H Miller
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Medicine ,Science - Abstract
Apical Membrane Antigen 1 (AMA1) of Plasmodium falciparum merozoites is a leading blood-stage malaria vaccine candidate. Protection of Aotus monkeys after vaccination with AMA1 correlates with antibody responses.A randomized, controlled, double-blind phase 1 clinical trial was conducted in 54 healthy Malian adults living in an area of intense seasonal malaria transmission to assess the safety and immunogenicity of the AMA1-C1 malaria vaccine. AMA1-C1 contains an equal mixture of yeast-expressed recombinant proteins based on sequences from the FVO and 3D7 clones of P. falciparum, adsorbed on Alhydrogel. The control vaccine was the hepatitis B vaccine (Recombivax). Participants were enrolled into 1 of 3 dose cohorts (n = 18 per cohort) and randomized 2:1 to receive either AMA1-C1 or Recombivax. Participants in the first, second, and third cohorts randomized to receive AMA1-C1 were vaccinated with 5, 20 and 80 microg of AMA1-C1, respectively. Vaccinations were administered on days 0, 28, and 360, and participants were followed until 6 months after the final vaccination. AMA1-C1 was well tolerated; no vaccine-related severe or serious adverse events were observed. AMA1 antibody responses to the 80 microg dose increased rapidly from baseline levels by days 14 and 28 after the first vaccination and continued to increase after the second vaccination. After a peak 14 days following the second vaccination, antibody levels decreased to baseline levels one year later at the time of the third vaccination that induced little or no increase in antibody levels.Although the AMA1-C1 vaccine candidate was well-tolerated and induced antibody responses to both vaccine and non-vaccine alleles, the antibody response after a third dose given at one year was lower than the response to the initial vaccinations. Additionally, post-vaccination increases in anti-AMA1 antibody levels were not associated with significant changes in in vitro growth inhibition of P. falciparum.ClinicalTrials.gov NCT00343005.
- Published
- 2007
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