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)

Antibody responses to the circumsporozoite (CS) protein of Plasmodium falciparum have previously been reported against the central repeating tetrapeptides of this protein. Segments of the protein flanking the repeat region also contain B-cell epitopes, but specific antibody responses have not been previously characterized. Longitudinal serum sets from 16 Thai adults who developed acute falciparum malaria were selected to represent a spectrum of antibody response to the repeat region (R32). These sera were assayed by enzyme-linked immunosorbent assay using as capture antigen a recombinant fusion protein, NS1(81)RLF, which contains both flanking regions, but lacks the NANP and NVDP repeats of the P. falciparum CS protein. Antibody responses to the repeatless flanking (RLF) regions were observed in all subjects, including five individuals who lacked detectable anti-R32 antibody responses. Anti-RLF antibody responses induced by natural infection appear to be short-lived and of low-to-moderate magnitude. Thus, if anti-RLF antibodies prove to be protective, derived vaccine candidates may require presentation of these epitopes with adjuvants or delivery systems that enhance immunogenicity.
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PMID:Characterization of naturally acquired antibodies to the non-repetitive flanking regions of the circumsporozoite protein of Plasmodium falciparum. 144 40

The repeat region of the Plasmodium vivax circumsporozoite (CS) protein contains 20 copies of the nine-amino acid sequence DRA A/D GQPAG. A monoclonal antibody that passively protects monkeys against sporozoite challenge recognizes a four-amino acid linear sequence AGDR included within this nonamer, but when monkeys were immunized with a vaccine, NS1(81)V20, which contains 20 copies of the nonamer, they failed to produce antibodies to AGDR. To determine if natural exposure to sporozoites induces antibodies to AGDR, we tested sera from 176 individuals from a malaria-endemic area in Flores, Indonesia. Seventy-one percent of the adults had antibodies to the P. vivax repeat region; only 18% had detectable antibodies to AGDR. None of the subjects had antibodies to the P. vivax variant repeat ANGAGNQPG. We next tested sera from six human volunteers immunized with NS1(81)V20 and found that the vaccine, despite inducing antibodies against the nonamer, as it did in the monkeys, did not induce antibodies against AGDR. To further test our ability to raise anti-AGDR antibodies using synthetic peptides, we immunized Aotus monkeys and BALB/c mice with AGDR. Sera from the mice reacted strongly with both AGDR and a recombinant protein containing the 20 copies of the nonamer. Sera from the monkeys reacted only minimally with a protein (VIVAX-1) that contains monomeric AGDR within its sequence. Sera from the mice also bound air-dried P. vivax sporozoites, while sera from the monkeys did not.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Low immunogenicity of a Plasmodium vivax circumsporozoite protein epitope bound by a protective monoclonal antibody. 147 43

Individuals living in a malaria-endemic area in northern Peru were found to have antibodies to the variant repeat sequence of the circumsporozoite (CS) protein of Plasmodium vivax. The presence of IgG antibody to the predominant repeat sequence GDRAA/DGPA represented by the recombinant protein NS1(81) V20 (V20), and the variant repeat sequence ANGAGNQPG contained in the synthetic peptide Pvk247, was determined by enzyme-linked immunosorbent assay. IgG antibodies to the repeats were present in 78 (26%) of 298 serum samples; 56% of the positive serum samples had antibodies to V20 and 60% had antibodies to Pvk247. These findings stress the importance of considering the variant epitope in designing a vaccine based on the repeat region of the vivax CS protein. In a malaria-endemic area such as the one in this study, in which exposure to the variant repeat epitope may be as frequent as exposure to the predominant repeat, a vaccine based solely on the predominant repeat epitope may be ineffective against the variant form.
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PMID:Prevalence of antibody to the variant repeat of the circumsporozoite protein of Plasmodium vivax in Peru. 162 95

We studied the interaction of sera from residents of an area in northern Peru where vivax malaria is endemic with four recombinant DNA-derived circumsporozoite (CS) proteins of Plasmodium vivax. The antigens used in the enzyme-linked immunosorbent assay included one Escherichia coli-produced and three Saccharomyces cerevisiae-produced recombinant proteins. Three of the proteins (NS1(81)V20, Vivax-1, and Vivax-2) contain the entire central repeat region of the P. vivax CS protein, and one protein (Vivax-3) contains only two repeat sequences. Vivax-1, Vivax-2, and Vivax-3 contain different lengths of sequences flanking the repeats. A higher percentage of the sera had antibodies to Vivax-2 and Vivax-3, the two proteins containing the longest nonrepeat sequences, than to NS1(81)V20 or Vivax-1. Children less than 5 years of age did not have immunoglobulin G antibodies to NS1(81)V20; however, they had antibodies to Vivax-1, Vivax-2, and Vivax-3. The finding that individuals living in a malaria-endemic area produce antibodies to peptides containing nonrepeat regions of the CS protein emphasizes the need to characterize the immune response to these regions in naturally exposed and experimentally immunized humans.
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PMID:Antibody response of humans to the circumsporozoite protein of Plasmodium vivax. 185 98

This paper presents results from analysis of a sample of SK&F 105154 (R32NS1(81], a malaria vaccine candidate produced in Escherichia coli, and discusses some analytical issues of general relevance to the characterization of such products derived from recombinant DNA technology. Anomalous migration and staining behavior were observed in sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Reversed-phase liquid chromatography (RPLC) appeared to resolve four minor components from the principal band, but the minor peaks were found to consist of numerous components resolvable by SDS-PAGE. Western blotting visualized certain components that were not adequately stained by either Coomassie or silver stain. None of the techniques that were employed were individually adequate to characterize the sample, but, taken together, were adequate to characterize the sample and to identify one principal degradation pathway. Degradation within the NS1(81) region decreases the RPLC retention time, while degradation within the R32 segment increases the retention time.
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PMID:Reversed-phase liquid chromatography and sodium dodecyl sulfate polyacrylamide gel electrophoresis characteristics of a recombinant DNA derived malaria antigen. 306 Apr 76

The aim of this study was to determine the exposure of child citizens of the United Arab Emirates (UAE) to Plasmodium vivax, and to elucidate if it was related to place of residence or previous international travel to malaria-endemic areas. Blood samples were collected from 1010 primary schoolchildren resident in 7 out of 9 districts of the UAE during October and November 1999. Plasma samples were tested for antibodies against MAP4 (DGQPAGDR)3P2P30, a multiple antigen peptide containing the repeat amino acid sequences of P. vivax circumsporozoite protein (CSP), conjugated to 2 T-helper epitopes, P2 (QYIKANSKFIGITE) and P30 (FNNFTVSFWLRVPKVSASHLE) from tetanus toxin. For confirmation of P. vivax-specific reactivity, positive samples were further tested against (AGDR)6, a synthetic peptide containing 6 copies of a protective epitope within the CSP, and against a recombinant CSP, designated as NS1(81)V20. Results indicated that 3.3% of the children were seropositive. The seropositivity rates differed significantly in relation to place of residence, whereas travel outside the UAE did not significantly affect the exposure rates to P. vivax.
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PMID:Seroprevalence of antibodies to repetitive domains of Plasmodium vivax circumsporozoite protein in United Arab Emirates children. 1247 90

We conducted a dengue seroprevalence survey among febrile patients positive or negative for malaria in Ibadan, Nigeria. Dengue IgG and NS1 seroprevalence of 73% and 35%, respectively, was observed, and 43% of those with malaria had acute dengue infection (NS1 determination). On the other hand, all participants with malaria were IgG dengue seropositive consistent with the endemicity of both arthropod-borne infections in the region. These data indicate that dengue is emerging as a major and neglected cause of fever in Nigeria.
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PMID:High dengue NS1 antigenemia in febrile patients in Ibadan, Nigeria. 2508 78

Because the prevalence of dengue fever in urban settings in Papua New Guinea is unknown, we investigated the presence of dengue using the NS1 antigen test in an outpatient-based prospective observational study at Port Moresby General Hospital. Of 140 patients with acute febrile illnesses, dengue fever was diagnosed in 14.9% (20 of 134; 95% confidence interval [95% CI] = 9.6-22.4). Malaria (2 of 137; 1.5%; 95% CI = 0.3-5.7), chikungunya (3 of 140; 2.1%; 95% CI = 0.6-6.6), and bacterial bloodstream infections (0 of 80; 0%; 95% CI = 0-5.7) were uncommon. Dengue fever should no longer be considered rare in Papua New Guinea.
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PMID:Prevalence of patients with acute febrile illnesses and positive dengue NS1 tests in a tertiary hospital in Papua New Guinea. 2533 3

Most febrile patients are often misdiagnosed with malaria due to similar symptoms, such as fever shared by malaria and certain arboviral infections. This study surveyed the incidence of malaria, chikungunya and dengue infections among a number of suspected febrile patients visiting Simawa Health Centre, Ogun State, Nigeria. Venous blood samples were obtained from 60 febrile patients (age 3-70 years) visiting the centre between April and May 2014. The rapid diagnostic test (RDT) was used to detect the presence of chikungunya (CHK) antibodies (IgM), dengue (DEN) virus and antibodies (NS1, IgM and IgG) and malaria parasites (Plasmodium falciparum and Plasmodium vivax). Malarial confirmatory tests were by microscopy and nested polymerase chain reaction (PCR) using the polymorphic region of Glutamate-Rich Protein (GLURP) gene. The complexity of P. falciparum infection in the community also determined by the use of nested PCR. These three mosquito-borne infections were observed in 63% (38) of the patients. The prevalence of CHK, DEN and malarial infections singularly were 11%, 0% and 63%, respectively, whereas malaria with either CHK or DEN infections were 24% (9) and 3% (1), respectively. No subjects were positive for CHK and DEN co-infection. Malarial microscopic confirmation was in 94% (32) of the malaria RDT-positive samples, 50% (17) were successfully analysed by nested PCR and the mean multiplicity of infection was 1.6 (1-3 clones). One patient sample harboured both P. falciparum and P. vivax. The study reports the presence of some arboviral infections having similar symptoms with malaria at Simawa, Ogun State. The proper diagnosis of infectious diseases is important for controlling them.
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PMID:A survey of malaria and some arboviral infections among suspected febrile patients visiting a health centre in Simawa, Ogun State, Nigeria. 2625 13

Dengue fever has become a worldwide public health concern, threatening an estimated 40% of the world's population. However, most resources and attention are still focused on malaria, while dengue statuses are poorly recognized in many African countries. In this serological survey, dengue virus (DENV) transmission was demonstrated by using serum samples collected from 78 pregnant women in the Democratic Republic of Sao Tome and Principe (DRSTP) during 2003 to 2004. Immunofluorescence assay was performed and 31 samples (39.74%) were found positive for DENV antibodies. Indirect enzyme-linked immunosorbent assay (ELISA) showed that 53 samples (67.95%) were positive for dengue E IgG, and 38 samples (48.72%) were positive for NS1 IgG. A prevalence of 35.90% was therefore determined for dengue IgG by considering samples that yielded positive results by all three tests. Cross-reactions with other flaviviruses were examined by indirect ELISA against Japanese encephalitis virus, West Nile virus, and yellow fever virus. Only one sample exhibited stronger absorbance against Japanese encephalitis virus and West Nile virus. Moreover, one sample was positive for dengue IgM. These results agreed with the previous researches in neighboring countries and suggested DENV exposure. The study contributes to raising public awareness of dengue and supporting future control strategies.
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PMID:Seroprevalence of antibodies against dengue virus among pregnant women in the Democratic Republic of Sao Tome and Principe. 2673 53


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