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)

DNA fragments from human malaria parasites were cloned into lambda gt11 to produce a genomic DNA expression library. A pool of monoclonal antibodies (mAbs) recognizing three domains of the 195-kDa major merozoite surface glycoprotein (gp195) reacted with seven clones expressing malaria antigens. mAbs recognizing the 83-kDa product of gp195 reacted with the clones, but mAbs recognizing a glycosylated 45-kDa and a nonglycosylated 45-kDa domain did not. Restriction enzyme mapping revealed that the clones contained overlapping segments encoding about 70% of the gene beginning at the 5' end and ending at an EcoRI restriction enzyme site 3.3 kilobase pairs downstream. The mAbs recognizing the 83-kDa domain reacted differently with the clones, allowing the mapping of three epitopes, one of which was repetitive. Affinity-purified antibodies were selected from immune monkey serum with recombinant expression proteins adsorbed to nitrocellulose filters. When used to probe electrophoretic immunoblots of parasite extracts, these antigen-selected antibodies reacted with specific sets of processed products of gp195, including those associated with the 83- and the nonglycosylated 45-kDa domains. This information, combined with the mAb epitope map, allowed a tentative scheme for processing gp195 from the Camp strain to be proposed.
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PMID:Epitope map and processing scheme for the 195,000-dalton surface glycoprotein of Plasmodium falciparum merozoites deduced from cloned overlapping segments of the gene. 242 62

Schizonts of the malaria parasite Plasmodium falciparum synthesize a 195 kDa surface glycoprotein (gp195) that is processed into several smaller products including one of 83 kDa, which, in the case of the Camp strain, is sequentially processed into 73 and 67 kDa products. gp195 and its processing intermediates larger than 83 kDa were not precipitated from culture supernates, but the 83 and 73 kDa products were precipitated by three monoclonal antibodies (McAbs). The 83 and 73 kDa products were affinity purified from culture supernates by adsorbing to McAb 7B2 coupled to Affigel 10 and eluting either with 0.2 N acetic acid, pH 2.8, or with 3 M potassium isothiocyanate (KSCN). The epitope recognized by McAb 7B2 was denatured by acid elution but could be regenerated by treating with 8 M urea followed by dialysis. The implications of renaturing antigens to regenerate epitopes should be considered in studies on the purification, function and immunogenicity of malaria antigens.
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PMID:Characterization of gp195 processed products purified from Plasmodium falciparum culture supernates. 244 21

Epidemics of a malaria-like illness affected several thousand residents of the Dam Camp, a refugee camp near Hargeysa in Somalia, during 1985, 1986, and 1987. The disease was characterized by fever, chills, sweats, headache, back and joint pains for as long as 10 days in some patients. Blood smears from acutely ill patients were negative for malaria. Of 28 acute and 10 convalescent sera tested by the indirect fluorescent antibody (IFA) and by the hemagglutination inhibition (HI) tests, all were negative for antibody to Rift Valley fever, Crimean-Congo hemorrhagic fever, Sindbis, Chikungunya, yellow fever, and Zika viruses. However, antibody reactive to dengue 2 virus was detected by the IFA test in 39% (15/38), and 11 of 29 (38%) of the same sera were antibody positive by the HI test. Also, IgG antibody reactive to dengue 2 was demonstrated in 60% (17/28) of the same sera by the enzyme immunoassay (EIA), and 14% (4/28) were positive for IgM antibody. Of ten patients for which acute and convalescent sera were available, two developed four fold or greater rises in antibody titer evidencing infection. These data suggested that dengue virus may have been the cause of the epidemic among the Dam Camp refugees.
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PMID:Serological evidence of dengue fever among refugees, Hargeysa, Somalia. 260 May 91

Invasion of erythrocytes by malaria merozoites requires the formation of a junction of attachment between erythrocyte and merozoite membranes. The attachment junction initially forms at the apical region of the merozoite. It then moves around to the posterior of the merozoite as invasion proceeds. A monoclonal antibody against a 60-kDa merozoite protein (termed MCP-1 for merozoite capping protein 1) of Plasmodium falciparum reacts in an immunofluorescence pattern resembling the moving junction. By two-color immunofluorescence, MCP-1 was located at the attachment site formed between the merozoite apical region and erythrocyte. During invasion, MCP-1 separated and migrated around merozoites at the orifice of the parasitophorous vacuole. In newly-invaded erythrocytes, MCP-1 persisted at the pole of the young parasite nearest the erythrocyte membrane, suggesting its anterior-to-posterior movement. MCP-1 exhibited no variability in molecular mass among the FCR-3, Camp and 7G8 strains of P. falciparum, and the epitope was invariant in the P. falciparum strains studied. We conclude that MCP-1 may participate in merozoite invasion of erythrocytes by facilitating attachment or movement of the junction along the parasite cytoskeletal network.
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PMID:A 60-kDa Plasmodium falciparum protein at the moving junction formed between merozoite and erythrocyte during invasion. 267 26

An interspersed repetitive DNA element from the Camp strain of the human malaria parasite Plasmodium falciparum was cloned and sequenced. The element is repeated at least 11 times in the genome, is a minimum of 2.0 kilobases long and maps to eight or more different parasite chromosomes. The cloned DNA includes a 1.0 kilobase open reading frame. RNA complementary to the repetitive element is found within blood stage forms of the parasite, but only in the most mature forms. Searches of DNA and protein sequence databases for homology to the element were unsuccessful. Sizes of restriction enzyme fragments which hybridize to the element show considerable variation between strains, indicating that the repeat family represented by this element could be transposable.
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PMID:Interspersed repetitive DNA from Plasmodium falciparum. 284 73

DNA encoding an antigen of 101,000 apparent molecular weight from the human malaria parasite Plasmodium falciparum was cloned and sequenced. Genomic DNA from the Camp strain covering the complete coding region along with cDNA from the FCR3 strain covering 81% of the coding region were obtained. The cloned DNA specified a full-length protein of 743 amino acids which included two tandemly repeated regions, one near the amino terminus containing eight hexapeptide repeats of sequence TVNDEDED, and the second near the carboxyl terminus containing primarily KE and KEE repeats. The latter repeated region is encoded by a 174-base stretch of mRNA containing only a single pyrimidine. Except for a putative leader sequence located at the amino terminus of the protein, the protein is hydrophilic and highly charged with a calculated isoelectric point of 5.6. Sequences from the Camp and FCR3 strains are very close and are also nearly identical to the partial cDNA sequence of the acidic basic repeated antigen (ABRA) protein from the FC27 strain (Stahl, H.D., Bianco, A.E., Crewther, R.F., Anders, R.F., Kyne, A.P., Coppel, R. L., Mitchell, G.F., Kemp, D.J., and Brown, G.V. (1986) Mol. Biol. Med. 3, 351-368). ABRA was previously shown to be located at the merozoite surface and in the parasitophorous vacuole. Because of its location and because it becomes complexed to merozoites when schizonts rupture in the presence of immune serum, ABRA is a candidate component of a malaria vaccine.
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PMID:Primary structure of a Plasmodium falciparum malaria antigen located at the merozoite surface and within the parasitophorous vacuole. 304 68

Plasmodium falciparum malaria merozoites require erythrocyte sialic acid for optimal invasion of human erythrocytes. Since mouse erythrocytes have the form of sialic acid found on human erythrocytes (N-acetyl neuraminic acid), mouse erythrocytes were tested for invasion in vitro. The Camp and 7G8 strains of P. falciparum invaded mouse erythrocytes at 17-45% of the invasion rate of human erythrocytes. Newly invaded mouse erythrocytes morphologically resembled parasitized human erythrocytes as shown on Giemsa-stained blood films and by electron microscopy. The rim of parasitized mouse erythrocytes contained the P. falciparum 155-kD protein, which is on the rim of ring-infected human erythrocytes. Camp but not 7G8 invaded rat erythrocytes, indicating receptor heterogeneity. These data suggest that it may be possible to adapt the asexual erythrocytic stage of P. falciparum to rodents. The development of a rodent model of P. falciparum malaria could facilitate vaccine development.
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PMID:Invasion of mouse erythrocytes by the human malaria parasite, Plasmodium falciparum. 329 9

Plasmodium falciparum malaria parasites with different capabilities of invading sialic acid-deficient erythrocytes were identified. Thai-2 parasites cultured in Tn erythrocytes invaded neuraminidase-treated and Tn erythrocytes twice as efficiently as Thai-2 parasites cultured in normal erythrocytes and seven to ten times more efficiently than a cloned line of Camp parasites cultured in normal erythrocytes. All three parasite lines required sialic acid for optimal invasion, but Thai-2 parasites cultured in Tn erythrocytes invaded neuraminidase-treated erythrocytes with 45% efficiency whereas Camp parasites invaded neuraminidase-treated erythrocytes with less than 10% efficiency. P falciparum malaria parasites probably possess two receptors: one that binds to a sialic acid-dependent ligand and another that binds to a sialic acid-independent ligand. Parasites may differ in the quantity or affinity of their receptors for the sialic acid-independent ligand.
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PMID:Invasion of erythrocytes by Plasmodium falciparum malaria parasites: evidence for receptor heterogeneity and two receptors. 351 59

Human retroplacental serum (RPS) containing polyamine oxidase inhibited the growth of the Camp strain of Plasmodium falciparum in vitro as assayed by the parasite's decreased incorporation of 3H-hypoxanthine. Inhibition was dose-dependent on the concentrations of serum polyamine oxidase and added polyamines. Almost complete inhibition was seen in 96-hr asynchronous cultures containing 10% RPS and in those containing 1.2% RPS plus 50 microM polyamine. Subtle morphologic changes in mature stages and decreased numbers of new rings were associated with inhibition seen in 19-hr synchronous cultures initiated at the trophozoite stage. These incubation times were longer than in previous reports showing inhibition of malaria parasites by bovine polyamine oxidase but not by human polyamine oxidase. Macrophages contain polyamine oxidase, the reaction products of which are known to be similar to those of RPS polyamine oxidase but different from those of bovine polyamine oxidase. It remains to be determined whether human polyamine oxidase, acting upon ubiquitous polyamines, contributes to host defenses against malaria.
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PMID:Polyamine oxidase in human retroplacental serum inhibits the growth of Plasmodium falciparum. 353 45

In vitro growth inhibition assays were used to detect antigenic differences among geographically distinct strains of Plasmodium falciparum. Owl monkeys were immunized against the Camp and FCR-3/FMG strains of P. falciparum by infection, drug treatment, and rechallenge with homologous parasites. Camp-immune monkey serum was used to inhibit the in vitro growth of eight strains of P. falciparum. Inhibition was maximum for the homologous Camp strain (an average of 62% inhibition by 100 ml/litre Camp-immune serum). Four other strains were inhibited to a lesser degree, and three strains (FCR-3/FMG, FVO, and Smith) were not significantly inhibited by Camp-immune serum at concentrations as high as 400 ml/litre. FCR-3/FMG-immune serum at a concentration of 50 ml/litre caused significant inhibition of the FCR-3/FMG strain, but not the Camp strain. Thus Camp and FCR-3/FMG strains appear to bear distinct antigenic determinants recognized by the homologous, but not the heterologous, antiserum. Inhibition of in vitro growth by immune serum may be useful for serotyping P. falciparum and may have application in the selection of strains for inclusion in a malaria vaccine.
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PMID:Serotypes of Plasmodium falciparum defined by immune serum inhibition of in vitro growth. 389 75


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