Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0024530 (malaria)
 44,886 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The hybrid synthetic protein SPf(66), which contains small fragments of the 83-kD, 55-kD, 35-kD, and circumsporozoite antigens of Plasmodium falciparum, was studied to determine its protective capacity against malaria infection in Aotus lemurinus monkeys. Two groups of six monkeys each were immunized six times with this polymer, which was mixed with either Freund's adjuvant or aluminum hydroxide. Two groups of five animals each were used as controls and immunized with saline solution mixed with the same adjuvants. Neither antipeptide nor antimalarial antibodies developed after the six immunization doses. Regardless of this fact, the monkeys were challenged intravenously with 10(5) P. falciparum blood stage parasites, and the resultant parasitemia was followed daily on blood smears. Only one monkey from each of the groups immunized using Freund's adjuvant (both experimental and control) was protected. In those immunized using aluminum hydroxide, one animal was protected in the experimental group, but none were protected in the control group. Anti-parasite antibodies developed during the infection, but did not correlate with protection and failed to recognize SPf(66) peptide in an enzyme-linked immunosorbent assay. Immunization with the polymer did not boost natural antibodies present in two of the monkeys before the experiment. Low levels of gamma-interferon were produced in some animals, but were not correlated with protection.
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PMID:Failure of a synthetic vaccine to protect Aotus lemurinus against asexual blood stages of Plasmodium falciparum. 144 9

A Plasmodium falciparum glycophorin binding protein (GBP-130) has been implicated in protective immunity to malaria. The gene for GBP-130 encodes a protein containing 11 tandemly repetitive 50 amino acid units. We report an immunization trial in Aotus monkeys using a recombinant DNA protein containing three of these 50 amino acid repeats. When administered with aluminum hydroxide, this antigen induced low levels of antibodies that reacted with the recombinant protein by ELISA and with parasite antigens in immunoblot and immunofluorescence assays, but not by immunoprecipitation. When administered with Freund's complete adjuvant, this antigen induced high levels of antibodies that reacted in ELISA, immunoblot, immunofluorescence, and immunoprecipitation assays. Serum from immunized monkeys did not inhibit parasite growth, and protection from intravenous challenge with P. falciparum-infected erythrocytes was not observed in any experimental group. These results suggest that the repetitive region of GBP-130 is not a useful vaccine candidate.
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PMID:Immunization of owl monkeys with a recombinant protein containing repeated epitopes of a Plasmodium falciparum glycophorin-binding protein. 171 34

A recombinant Plasmodium vivax circumsporozoite (CS) antigen representing approximately 70% of the CS protein was expressed in yeast and adsorbed onto aluminum hydroxide for use as a malaria vaccine. In a study of safety and immunogenicity, 30 volunteers were divided into four groups of 5, 5, 10, and 10 individuals, and inoculated intramuscularly with 50, 100, 200, or 400 micrograms of vaccine, respectively. Primary vaccinations were followed by two booster immunizations at six weeks and six months. Overall, the vaccine was well tolerated. Following the third vaccination, one volunteer developed acute hepatitis of uncertain etiology that resolved without sequelae. All volunteers in the 400-micrograms group, and six of 10 in the 200-micrograms group generated IgG against P. vivax CS protein, as determined by Western blot using recombinant CS protein. However, the magnitude of the antibody response measured by indirect immunofluorescence of intact sporozoites or enzyme-linked immunosorbent assay against the recombinant protein was low, and responses could not be boosted. Antigen-driven replication studies using peripheral blood lymphocytes failed to detect proliferative responses specific to peptide sequences represented in the recombinant vaccine, except in one volunteer. Minimal humoral and cell-mediated immune responses developed in most recipients who received this recombinant CS vaccine.
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PMID:Safety and immunogenicity of a recombinant sporozoite malaria vaccine against Plasmodium vivax. 176 96

Soluble Plasmodium falciparum polypeptides, affinity-purified from culture supernatant fluids using sequential immunoadsorptions employing both monoclonal and polyclonal antibodies, induced protective immunity against experimental falciparum malaria in Peruvian Aotus nancymai monkeys. Susceptible monkeys were vaccinated with polypeptides affinity-purified from supernatant fluids of P. falciparum Indochina I/CDC cultures. Eighteen animals (6 immunized with purified antigens plus adjuvants, 6 injected with only the adjuvant preparation, and 6 untreated) were challenged with whole blood containing monkey-adapted virulent organisms of the Indochina I/CDC strain. Selected hematologic, serologic and parasitologic profiles served as potential indicators of protection. This immunogen, when fortified with an aluminum hydroxide/Quil-A saponin adjuvant combination, elicited good antibody responses to major P. falciparum antigens. Protection in vaccinated animals was evidenced by a significantly limited reduction in hematocrit and hemoglobin levels and a relatively moderate course of infection after homologous needle-challenge with Aotus monkey-adapted P. falciparum parasites.
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PMID:Immunogenicity and protective efficacy of affinity-purified Plasmodium falciparum exoantigens in Aotus nancymai monkeys. 205 57

The immunogenicity of a malaria peptide presented in various forms was tested in terms of the quality and quantity of the antibody response in rabbits. Peptide conjugated to a protein carrier, diphtheria toxoid (DT), required strong adjuvants (e.g. muramyl dipeptide, MDP and Freund's adjuvant, FCA) to elicit high levels of antibody with high avidity. Alum was a poor adjuvant, producing the lowest titre and avidity of antibody compared with all the other groups. Peptide expressed in vaccinia (and without carrier) produced intermediate levels of antibody but the avidity of the antibodies produced were comparable to that produced by peptide conjugates given with muramyl dipeptide.
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PMID:Comparison of antibody avidity and titre elicited by peptide as a protein conjugate or as expressed in vaccinia. 305 55

Eleven volunteers were injected with an anti-malaria (Plasmodium falciparum) sporozoite vaccine candidate consisting of a synthetic peptide, Ac-Cys-(NANP)3, coupled to tetanus toxoid (TT) and adsorbed to aluminum hydroxide. Two of the volunteers had no previously known exposure to TT. Eight volunteers made detectable antipeptide, anticircumsporozoite protein or antisporozoite antibodies, whose titers increased after multiple injections in four individuals. The maximum antisporozoite titer obtained in an immunofluorescence assay was 1280. In those individuals who produced antipeptide antibody, the overall correlation between IgG anti-Ac-Cys-(NANP)3 antibody in enzyme-linked immunosorbent assay and IgG antisporozoite reactivity in immunofluorescence was highly significant. However, the fine specificity of antibody varied among volunteers with two individuals producing mostly antipeptide antibody. Anti-TT antibody responses increased in all volunteers with the exception of that person who had the highest pretrial anti-TT titer; this individual was one of the two pre-TT-immunized volunteers who failed to produce anti-Ac-Cys-(NANP)3 or sporozoite antibody. For the two non-TT preimmunized volunteers, one produced an antisporozoite fluorescence titer of 320; the other made no detectable antibody against either Ac-Cys-(NANP)3 or sporozoites during a primary response. For the three volunteers monitored, after the first injection, significant T cell proliferative responses to (NANP)3 were observed, which increased up to 4 wk after immunization, when a second injection was given. Responsiveness then declined to background levels and did not reappear after further immunizations. In contrast, a marked TT-specific proliferation was observed for the duration of the study.
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PMID:Assessment in humans of a synthetic peptide-based vaccine against the sporozoite stage of the human malaria parasite, Plasmodium falciparum. 327 19

Soluble Plasmodium falciparum exoantigens in crude culture supernatant fluids induced protective immunity against experimental falciparum malaria in Bolivian Saimiri sciureus monkeys. Susceptible squirrel monkeys were vaccinated with an aluminum hydroxide-fortified fraction purified from culture supernatants of P. falciparum Indochina I and Geneve/SGE-1 by cation-exchange (sulfopropyl-trisacryl) chromatography. Animals immunized with sulfopropyl-purified and corresponding control immunogens were challenged with whole blood containing monkey-adapted virulent organisms of the Indochina I strain. Hematological, serological, and parasitological profiles, including the appearance of crisis forms, served as potential indicators of protection. This immunogen conferred significant clinical protection of squirrel monkeys against needle challenge with the homologous Indochina I strain and a moderate degree of heterologous strain immunity.
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PMID:Induction of protective immunity to Plasmodium falciparum in Saimiri sciureus monkeys with partially purified exoantigens. 389 52

Merozoite surface protein 1 is a candidate for blood-stage vaccines against malaria parasites. We report here an immunization study of Saimiri monkeys with a yeast-expressed recombinant protein containing the C terminus of Plasmodium vivax merozoite surface protein 1 and two T-helper epitopes of tetanus toxin (yP2P30Pv20019), formulated in aluminum hydroxide (alum) and block copolymer P1005. Monkeys immunized three times with yP2P30Pv20019 in block copolymer P1005 had significantly higher prechallenge titers of immunoglobulin G (IgG) antibodies against the immunogen and asexual blood-stage parasites than those immunized with yP2P30Pv20019 in alum, antigen alone, or phosphate-buffered saline (PBS) (P < 0.05). Their peripheral blood mononuclear cell proliferative responses to immunogen stimulation 4 weeks after the second immunization were also significantly higher than those from the PBS control group (P < 0.05). Upon challenge with 100,000 asexual blood-stage parasites 5 weeks after the last immunization, monkeys immunized with yP2P30Pv20019 in block copolymer P1005 had prepatent periods longer than those for the control alone group (P > 0.05). Three of the five animals in this group also had low parasitemia (peak parasitemia, </=20 parasites/microliter of blood). Partially protected monkeys had significantly higher levels of prechallenge antibodies against the immunogen than those unprotected (P < 0.05). There was also a positive correlation between the prepatent period and titers of IgG antibodies against the immunogen and asexual blood-stage parasites and a negative correlation between accumulated parasitemia and titers of IgG antibodies against the immunogen (P < 0.05). These results indicate that when combined with block copolymer and potent T-helper epitopes, the yeast-expressed P2P30Pv20019 recombinant protein may offer some protection against malaria.
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PMID:Partial protection against Plasmodium vivax blood-stage infection in Saimiri monkeys by immunization with a recombinant C-terminal fragment of merozoite surface protein 1 in block copolymer adjuvant. 986 35

Multiple antigen peptides (MAPs) containing epitopes of the major surface protein of the malaria sporozoite, the circumsporozoite (CS) protein, have been shown in previous studies to elicit antibody-mediated protection against sporozoite challenge in experimental murine and simian hosts. For the preparation for a phase I trial of a P. falciparum (T1B)4 MAP, which contains T and B cell epitopes from the CS repeat region, pre-clinical immunogenicity and adjuvant formulation studies were carried out in mice and Aotus monkeys. The (T1B)4 MAP was found to be immunogenic in three different species of owl monkeys, Aotus nancymae, A. vociferans and A. nigriceps. Optimal antibody responses were obtained in A. nancymae immunized s.c. with (T1B)4 MAP emulsified in Freund's, in which peak titers of over 10(6) were obtained in individual monkeys. MAP immunized A. vociferans also developed high levels of anti-sporozoite antibodies, although the kinetics and the magnitude of the response differed from A. nancymae. (T1B)4 MAP adsorbed to alum (aluminum hydroxide), a formulation that is acceptable for human use, was less immunogenic in naive A. nancymae, as well as A. nigriceps. The injection of MAPs/alum, however, significantly enhanced antibody responses in sporozoite-primed monkeys, suggesting that the administration of the MAP vaccine may be an effective means to increase the low levels of antibody present in individuals living in malaria endemic areas. The addition of a co-adjuvant QS-21, a purified saponin, significantly increased the immunogenicity of the alum-adsorbed MAP in both mice and monkeys, providing a vaccine formulation suitable for phase I trials in human volunteers.
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PMID:Preclinical evaluation of a synthetic Plasmodium falciparum MAP malaria vaccine in Aotus monkeys and mice. 1050 Dec 39

Transmission-blocking vaccines are one strategy for controlling malaria, whereby sexual-stage parasites are inhibited from infecting mosquitoes by human antibodies. To evaluate whether the recently cloned Plasmodium vivax proteins Pvs25 and Pvs28 are candidates for a transmission-blocking vaccine, the molecules were expressed in yeast as secreted recombinant proteins. Mice vaccinated with these proteins adsorbed to aluminum hydroxide developed strong antibody responses against the immunogens, although for Pvs28, this response was genetically restricted. Antisera against both recombinant Pvs25 and Pvs28 recognized the corresponding molecules expressed by cultured sexual-stage parasites isolated from patients with P. vivax malaria. The development of malaria parasites in mosquitoes was completely inhibited when these antisera were ingested with the infected blood meal. Pvs25 and Pvs28, expressed in Saccharomyces cerevisiae, are as yet the only fully characterized transmission-blocking vaccine candidates against P. vivax that induce such a potent antiparasite response.
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PMID:Antibodies to malaria vaccine candidates Pvs25 and Pvs28 completely block the ability of Plasmodium vivax to infect mosquitoes. 1108 73


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