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Journal ArticleDOI

Diagnostic potential of monoclonal antibodies developed against C-terminal polypeptide of P. falciparum Histidine Rich Protein2 (PfHRP2) in malaria infected patients from India.

04 Aug 2017-Pathogens and Global Health (Informa UK Limited)-Vol. 111, Iss: 6, pp 297-305

TL;DR: The diagnostic performance of two anti-C-terminal PfHRP2 mAbs (b10c1 and Aa3c10) were evaluated with 100 blood samples from clinically identified malaria patients from seven different geographical centers in India and suggest that the anti- C-terminals have merits for improvising the existing malarial diagnostics.
Abstract: Malaria, caused by Plasmodium falciparum has become a major health burden in most tropical and developing countries. P. falciparum Histidine Rich Protein2 (PfHRP2), which exhibits polymorphism, is being widely used as a diagnostic marker. Recently, we reported the development of monoclonal antibodies against conserved C-terminal 105 amino acids of PfHRP2 for malaria diagnosis. Now, in this study, the diagnostic performance of two anti-C-terminal PfHRP2 mAbs (b10c1 and Aa3c10) were evaluated with 100 blood samples from clinically identified malaria patients from seven different geographical centers in India. Sandwich ELISA, polymerase chain reaction (PCR) and statistical tools were used for the evaluation of the performance of the anti-C-terminal PfHRP2 mAb. These mAbs detected P. falciparum (mean OD value 1.525 ± 0.56) malaria with great accuracy with no cross reactivity with P. Plasmodium vivax (mean OD value 0.285 ± 0.051) and normal healthy control samples (mean OD value 0.185 ± 0.06) in Sandwich ELISA assay. The samples which were RDT negative for P. falciparum were also reactive in Sandwich ELISA with mean OD value of (1.303 ± 0.532). The amount of PfHRP2 antigen in the patients' blood sample was quantified and categorized into three distinct groups having the HRP2 antigen in high, intermediate and low amounts. The presence of Pfhrp2 gene was also confirmed by PCR analysis. The sensitivity and specificity of the mAb were found to be 95 and 96% respectively. These data strongly suggest that the anti-C-terminal PfHRP2 mAbs b10c1 and Aa3c10 have merits for improvising the existing malarial diagnostics.
Topics: Plasmodium falciparum (57%), Plasmodium vivax (55%)
Citations
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Joanne Baker, Mei-Fong Ho1, Anita Pelecanos1, Michelle L. Gatton1  +24 moreInstitutions (9)
17 May 2010-
TL;DR: Despite extreme sequence variation, diversity of PfHRP2 does not appear to be a major cause of RDT sensitivity variation, and no statistically robust correlation between gene structure and RDT detection rate for P. falciparum parasites was identified.
Abstract: Background Accurate diagnosis is essential for prompt and appropriate treatment of malaria. While rapid diagnostic tests (RDTs) offer great potential to improve malaria diagnosis, the sensitivity of RDTs has been reported to be highly variable. One possible factor contributing to variable test performance is the diversity of parasite antigens. This is of particular concern for Plasmodium falciparum histidine-rich protein 2 (PfHRP2)-detecting RDTs since PfHRP2 has been reported to be highly variable in isolates of the Asia-Pacific region. Methods The pfhrp2 exon 2 fragment from 458 isolates of P. falciparum collected from 38 countries was amplified and sequenced. For a subset of 80 isolates, the exon 2 fragment of histidine-rich protein 3 (pfhrp3) was also amplified and sequenced. DNA sequence and statistical analysis of the variation observed in these genes was conducted. The potential impact of the pfhrp2 variation on RDT detection rates was examined by analysing the relationship between sequence characteristics of this gene and the results of the WHO product testing of malaria RDTs: Round 1 (2008), for 34 PfHRP2-detecting RDTs. Results Sequence analysis revealed extensive variations in the number and arrangement of various repeats encoded by the genes in parasite populations world-wide. However, no statistically robust correlation between gene structure and RDT detection rate for P. falciparum parasites at 200 parasites per microlitre was identified. Conclusions The results suggest that despite extreme sequence variation, diversity of PfHRP2 does not appear to be a major cause of RDT sensitivity variation.

118 citations


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TL;DR: Most new technology for malaria diagnosis incorporates immunochromatographic capture procedures, with conjugated monoclonal antibodies providing the indicator of infection, and clinical studies allow effective comparisons between different formats.
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Nicholas J. White1Institutions (1)
TL;DR: Widespread use of these drugs could roll back malaria and Artemisinin-derivative combinations are particularly effective, since they act rapidly and are well tolerated and highly effective.
Abstract: Malaria, the most prevalent and most pernicious parasitic disease of humans, is estimated to kill between one and two million people, mainly children, each year. Resistance has emerged to all classes of antimalarial drugs except the artemisinins and is responsible for a recent increase in malaria-related mortality, particularly in Africa. The de novo emergence of resistance can be prevented by the use of antimalarial drug combinations. Artemisinin-derivative combinations are particularly effective, since they act rapidly and are well tolerated and highly effective. Widespread use of these drugs could roll back malaria.

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TL;DR: Many clinical tests are used to confirm or refute the presence of a disease or further the diagnostic process, but most clinical tests fall short of the ideal of correctly identifying all patients with the disease and all patients who are disease free.
Abstract: Many clinical tests are used to confirm or refute the presence of a disease or further the diagnostic process. Ideally such tests correctly identify all patients with the disease, and similarly correctly identify all patients who are disease free. In other words, a perfect test is never positive in a patient who is disease free and is never negative in a patient who is in fact diseased. Most clinical tests fall short of this ideal.

739 citations


Journal ArticleDOI
24 Feb 2014-PLOS ONE
TL;DR: Differences in historic and recent hospital cohorts in the diagnosis and treatment of febrile illness in a low malaria prevalence area of northern Tanzania are assessed to assess changes in the treatment of malaria and bacterial infections.
Abstract: In 2010, the World Health Organization (WHO) published updated guidelines emphasizing and expanding recommendations for a parasitological confirmation of malaria before treating with antimalarials. This study aimed to assess differences in historic (2007–2008) (cohort 1) and recent (2011–2012) (cohort 2) hospital cohorts in the diagnosis and treatment of febrile illness in a low malaria prevalence area of northern Tanzania. We analyzed data from two prospective cohort studies that enrolled febrile adolescents and adults aged $13 years. All patients received quality-controlled aerobic blood cultures and malaria smears. We compared patients’ discharge diagnoses, treatments, and outcomes to assess changes in the treatment of malaria and bacterial infections. In total, 595 febrile inpatients were enrolled from two referral hospitals in Moshi, Tanzania. Laboratory-confirmed malaria was detected in 13 (3.2%) of 402 patients in cohort 1 and 1 (0.5%) of 193 patients in cohort 2 (p = 0.041). Antimalarials were prescribed to 201 (51.7%) of 389 smear-negative patients in cohort 1 and 97 (50.5%) of 192 smearnegative patients in cohort 2 (p = 0.794). Bacteremia was diagnosed from standard blood culture in 58 (14.5%) of 401 patients in cohort 1 compared to 18 (9.5%) of 190 patients in cohort 2 (p = 0.091). In cohort 1, 40 (69.0%) of 58 patients with a positive blood culture received antibacterials compared to 16 (88.9%) of 18 patients in cohort 2 (p = 0.094). In cohort 1, 43 (10.8%) of the 399 patients with known outcomes died during hospitalization compared with 12 (6.2%) deaths among 193 patients in cohort 2 (p = 0.073). In a setting of low malaria transmission, a high proportion of smear-negative patients were diagnosed with malaria and treated with antimalarials despite updated WHO guidelines on malaria treatment. Improved laboratory diagnostics for non-malaria febrile illness might help to curb this practice.

480 citations