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 nucleotide and deduced amino acid sequence of a serine protease (AgSp24D) from the human malaria vector, Anopheles gambiae, is presented. The gene product is a 271 amino acid protein that contains the conserved serine, histidine and aspartic acid residues found in serine proteases, and has the highest identity to a serine protease of unknown function from Drosophila melanogaster. In situ hybridization to the polytene chromosomes detects a single band at 24D. Northern analysis reveals only low levels of transcripts in larvae and pupae, but more abundant transcription products occur in adults. Interestingly, this analysis also shows that adult males express much higher levels of AgSp24D mRNA than females. In addition, Plasmodium-refractory mosquitoes express higher levels of AgSp24D mRNA than susceptible mosquitoes although the biological significance of this remains to be examined. The thorax is the primary site for expression in the adults. The lack of a dramatic increase in AgSp24D mRNA levels following blood feeding suggests that this protease is not involved in digestive processes. Transcriptional induction does not follow cold shock, septic wounding, bacterial injection, laminarin injection or CM-Sephadex bead injection.
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PMID:Cloning and characterization of a serine protease from the human malaria vector, Anopheles gambiae. 935 80

A rapid immunodiagnostic test (ICT Malaria PfTest) has been developed by ICT Diagnostics (Sydney, Australia) for the diagnosis of Plasmodium falciparum infection. The test is an antigen capture assay based on the detection of P. falciparum histidine-rich protein 2 in peripheral blood. This study was undertaken to assess the performance and usefulness of the test as a diagnostic method in highly malarious, inaccessible forested villages of Mandla district, central India. In all, 353 patients with fever were scanned by the test in parallel with thick blood film examination. The sensitivity and specificity were 100% and 84.5%, respectively. The whole test took about 5 min. The test results became negative in most cases (70%) within 7 d after initiation of curative chemotherapy. The test is simple, easy to learn and accurate, and may prove to be an important tool in the battle against falciparum malaria.
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PMID:Malaria diagnosis by field workers using an immunochromatographic test. 937 31

Plasmodium falciparum histidine rich protein 2 (PfHRP2) antigen was measured semi-quantitatively in whole blood, plasma, and supernatants and red blood cells of cultures in vitro using the dipstick ParaSight-F test and also by a quantitative antigen-capture enzyme-linked immunosorbent assay (ELISA). In vitro, PfHRP2 was secreted mainly during the second half of the asexual cycle with a marked rise during schizont development and rupture. The total PfHRP2 secreted before schizogony corresponded to approximately 4% of that contained in the red blood cells. In samples from 55 patients with acute falciparum malaria, the level of detection by ELISA corresponded to parasitaemias of 100/microL for whole blood and 1600/microL for separated plasma. Whole blood PfHRP2 levels were correlated significantly with admission parasitaemia (r = 0.76, P < 0.0001) and the stage of parasite development (r = 0.43, P < 0.01). Although whole blood PfHRP2 concentrations were higher in severe malaria, plasma concentrations of PfHRP2 were considerably higher in severe malaria (median titre 1:320, range zero to 1:1280) than in uncomplicated malaria (median titre 1:5, range zero to 1:80; P < 0.0001). The ratio of whole blood to plasma PfHRP2 was lower in severe than in uncomplicated malaria (median 4, range 0.25 to 256, versus 64, range 4 to 1280; P < 0.0001). With plasma samples the intensity of colour change on the dipstick correlated well with more precise measurement of optical density in the ELISA (r = 0.88, P < 0.0001). These results suggest that measurement of PfHRP2 in plasma could provide an alternative approach to the assessment of the parasite biomass, and thus prognosis, in severe malaria, and that this could be done simply by using the currently available dipsticks.
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PMID:Semi-quantitative measurement of Plasmodium falciparum antigen PfHRP2 in blood and plasma. 937 61

The rapid manual ParaSight-F test of Plasmodium falciparum malaria, an antigen capture test for detecting trophozoite-derived histidine rich protein-2 (PF HRP-2), is simple to perform and provides a definite diagnosis within 10 minutes. During an operational trial at health centers and mobile malaria units where microscopical diagnosis is not available and using defined symptom screening criteria, 3,361 subjects were tested yielding 618 positives (18.4%) for PF-HRP-2 by ParaSight-F. Microscopic examination of the same subjects by thick blood film examined 7 days later at a malaria clinic showed 578 falciparum, and 349 vivax and mixed infection (F+V) 41. The technology proved highly effective in detecting falciparum malaria at the peripheral levels where access to malaria laboratory services are difficult, thus allowing immediate administration of a complete course of treatment in the absence of a microscopic examination.
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PMID:Operational trial of ParaSight-F (dipstick) in the diagnosis of falciparum malaria at the primary health care level. 944

A field study was conducted to assess the sensitivity and specificity of rapid immunodiagnostic test based on detection of Plasmodium falciparum histidine-rich protein-2 (PfHRP-2) in peripheral blood for diagnosis of P. falciparum infection. Evaluation in 173 patients showed that the assay was 98.59% sensitive and 97.1% specific. There was no cross-reactivity with P. vivax. The test was positive in few patients who were found to be negative by microscopy showing the presence of antigen after curative chemotherapy. The test is a valuable diagnostic tool for falciparum malaria, especially in emergency/field situations requiring rapid diagnosis.
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PMID:A rapid immunochromatographic test (ICT) for diagnosis of Plasmodium falciparum. 958 85

A battery of sixty-six blood samples from Senegal was analysed by the ParaSight F test, the ICT Malaria PF and the Malaria IgG CELISA. These three assays detect the histidine rich protein 2 antigen of Plasmodium falciparum. Thick smear microscopy was used as the reference method. Sensitivity, specificity, predictive positive and negative values were respectively 89%, 100%, 100%, 88% for the ICT; 86%, 93%, 94%, 85% for the paraSight and 88%, 87%, 88%, 87% for the Malaria IgG CELISA. The three assays failed to detect two positive samples with P. ovale and P. malariae. Assays were also compared with regard to the expense of equipment and reagents and speed and ease of use. The rapid ICT and ParaSight F test can be performed with minimal training and may be specially useful in areas where P. falciparum is the predominant malaria species, in epidemic malaria regions, and where skilled microscopy is not readily available.
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PMID:Diagnosis of Plasmodium falciparum malaria using ParaSight F, ICT malaria PF and malaria IgG CELISA assays. 975 17

Rapid and accurate methods are needed for the diagnosis of imported malaria. The ParaSight-F test and the ICT Malaria Pf test are commercially available kits marketed for the diagnosis of Plasmodium falciparum malaria. Both tests are antigen-capture assays based on the detection of P. falciparum histidine-rich protein 2 in peripheral blood. Using microscopy and a polymerase chain reaction (PCR)-based method as reference standards, we performed a 'blinded' comparison of these assays for the detection of P. falciparum infection in 200 febrile travellers returning from malaria-endemic areas. As determined by PCR and microscopy, 148 travellers had malaria and, of these patients, 54.7% (81/148) were infected with P. vivax only, 31.1% (46/148) with P. falciparum only, 9.5% (14/148) with P. ovale, 0.7% (1/148) with P. malariae, and 4.1% (6/148) had mixed infections. Compared to PCR, the ParaSight-F and ICT Malaria Pf tests had initial sensitivities of 94% and 90% and specificities of 95% and 97%, respectively, for the detection of P. falciparum malaria. When discrepant samples were retested with day 0 and day 1 bloods, the sensitivities improved to 96% and 94%, respectively. The 2 remaining false negative results with the Para-Sight-F test and 2 of the 3 false negative results with the ICT Malaria Pf test occurred in samples with < 100 parasites/microL. The performance of these kits was not significantly different (P = 0.75) and both are simple, rapid, and accurate tests for the detection of P. falciparum infection in the returned traveller.
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PMID:Comparison of the ParaSight-F test and the ICT Malaria Pf test with the polymerase chain reaction for the diagnosis of Plasmodium falciparum malaria in travellers. 976 22

The ParaSight-F dipstick test (Becton Dickinson, USA) and the ICT Malaria Pf test (ICT, Australia) both detect histidine rich protein 2 (HRP-2), a water-soluble antigen expressed by Plasmodium falciparum trophozoites. The present study compared the diagnostic performance of both tests in persons returning to Belgium from countries endemic for malaria. During a period of 18 months both tests were performed on all patients returning from the tropics with a positive malaria blood film. Patients with fever without an obvious cause were used as controls. For the ParaSight-F test, considering P. falciparum trophozoites only, sensitivity was 95% and specificity 90%. Considering trophozoites of all species of Plasmodium, sensitivity was 71% and specificity 87%. Finally, considering patients with clinical malaria, the sensitivity of the test was 72% and specificity 87%. For the ICT Malaria Pf test, sensitivity was 95% and specificity 89% for P. falciparum trophozoites only, 71% and 86% for trophozoites of all species, and 72% and 87% for clinical malaria. Both tests gave highly comparable results. However, antigen detection assays cannot replace conventional microscopy in diagnosing imported malaria. Thick blood film examination is more sensitive and more specific, it allows estimation of parasitaemia and distinction between parasite growth stages, and it covers all species. Moreover, with treated patients the use of antigen tests might lead to problems in determining the efficacy of therapy.
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PMID:Evaluation of two tests based on the detection of histidine rich protein 2 for the diagnosis of imported Plasmodium falciparum malaria. 986 98

HLA-B*3910, which has only been found in African and African American individuals, differs from B*3901 by the single amino acid change of Cys67 to Tyr67. Sequence analysis of the B*3910-bound peptide pool and of several individual ligands revealed that this subtype has strong preference for peptides with Pro2. This is in contrast with the preference of B*3901 for peptides with basic residues (Arg and His) at this position, and indicates that the single amino acid substitution between B*3910 and B*3901 totally changes the repertoire of bound peptides. This is presumably due to the significant decrease in the size of the B pocket, and to its increased hydrophobicity, since Tyr67 takes part in this pocket. B*3910 is similar to various other class I proteins in its preference for peptides with Pro2 and nonpolar C-terminal residues, including HLA-B53, an antigen associated with protection against severe malaria. The role of these two motifs as major peptidic anchors suggests that B*3910 and HLA-B53 may bind common peptides.
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PMID:A single amino acid change makes the peptide specificity of B*3910 unrelated to B*3901 and closer to a group of HLA-B proteins including the malaria-protecting allotype HLA-B53. 986 30

Swift diagnosis of Plasmodium falciparum malaria in areas where the disease is not endemic is frequently complicated by the lack of experience on the side of involved laboratory personal. Diagnostic tools based on the dipstick principle for the detection of plasmodial histidine-rich protein 2 (HRP-2) and parasite-specific lactate dehydrogenase (pLDH), respectively, have become available for the qualitative detection of P. falciparum malaria. In order to evaluate two of the currently available assays, specimens from 231 patients were screened during a prospective multicenter study. Among the screened specimens, samples from 53 patients (22.9%) were positive for P. falciparum malaria by microscopy and/or PCR. While the test kit based on the detection of HRP-2 performed with a sensitivity of 92.5% and a specificity of 98.3%, the kit for the detection of pLDH showed a sensitivity of 88.5% and a specificity of 99.4%. Dipstick tests have the potential of enhancing speed and accuracy of the diagnosis of P. falciparum malaria, especially if nonspecialized laboratories are involved.
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PMID:Sensitivity and specificity of dipstick tests for rapid diagnosis of malaria in nonimmune travelers. 998 39


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