In some kits, labeled antibody is pre-deposited during manufacture and only a lysing/washing buffer is added. In general, the blood specimen (2 to 50µL) is either a finger-prick blood specimen, anticoagulated blood, or plasma, and it is mixed with a buffer solution that contains a hemolyzing compound and a specific antibody that is labeled with a visually detectable marker such as colloidal gold. The test procedure varies between the test kits. The RDTs have been developed in different test formats like the dipstick, strip, card, pad, well, or cassette and the latter has provided a more satisfactory device for safety and manipulation. With pLDH as the target, a quantitative immunocapture assay, a qualitative immunochromatographic dipstick assay using monoclonal antibodies, an immunodot assay, and a dipstick assay using polyclonal antibodies have been developed. It has been found in all 4 human malaria species, and different isomers of pLDH for each of the 4 species exist. Parasite lactate dehydrogenase (pLDH) is a soluble glycolytic enzyme produced by the asexual and sexual stages of the live parasites and it is present in and released from the parasite infectederythrocytes. Monoclonal antibodies against Plasmodium aldolase are pan-specific in their reaction and have been used in a combined ‘P.f/P.v’ immunochromatographic test that targets the pan malarial antigen (PMA) along with PfHRP2. falciparum as well as the non-fa1ciparum malaria parasites. Plasmodium aldolase is an enzyme of the parasite glycolytic pathway expressed by the blood stages of P. Several RDTs targeting PfHRP2 have been developed. falciparum, expressed on the red cell membrane surface, and shown to remain in the blood for at least 28 days after the initiation of antimalarial therapy. falciparum (PfHRP2) is a water soluble protein that is produced by the asexual stages and gametocytes of P. These RDTs do not require a laboratory, electricity, or any special equipment. falciparum, a pan-malarial Plasmodium aldolase, and the parasite specific lactate dehydrogenase. Currently, immunochromatographic tests can target the histidine-rich protein 2 of P. Immunochromatographic Tests for MalariaĪntigens Immunochromatographic tests are based on the capture of the parasite antigens from the peripheral blood using either monoclonal or polyclonal antibodies against the parasite antigen targets. The prospect of overcoming the problems associated with current RDTs with a new generation of alternative malaria antigen targets is also described.Although the peripheral blood smear examination that provides the most comprehensive information on a single test format has been the “gold standard” for the diagnosis of malaria, the immunochromatographic tests for the detection of malaria antigens, developed in the past decade, have opened a new and exciting avenue in malaria diagnosis. The difficulties associated with RDTs, such as genetic variability in the Pfhrp2 gene and the persistence of antigens in the bloodstream following the elimination of parasites, are discussed. This paper describes recent developments in malaria RDTs, reviewing RDTs detecting PfHRP2, pLDH and plasmodial aldolase. However, the specificities, sensitivities, numbers of false positives, numbers of false negatives and temperature tolerances of these tests vary considerably, illustrating the difficulties and challenges facing current RDTs. Tests targeting HRP2 contribute to more than 90% of the malaria RDTs in current use. Three antigens - Plasmodium falciparum histidine-rich protein 2 (PfHRP2), plasmodial aldolase and plasmodial lactate dehydrogenase (pLDH) - are currently used for RDTs. In the last decade, there has been an upsurge of interest in developing malaria rapid diagnostic test (RDT) kits for the detection of Plasmodium species.
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