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RDT Test antigens: review of advantages and disadvantages
Overview
Several forms of malarial protein may be used to identify malaria. Each serves very specific functions in parasites. One such protein (HRP2) is highly specific for P.falciparum and is not found in other malarial species (or humans) and is therefore used to detect that parasite. Other proteins used in diagnosis are found in the metabolic pathways of both humans and malarial parasites, but with structural differences between human and parasite forms, but in some cases also between the different malarial species. These different structural featues maen that antigenic epitopse allow antibodies to distinguish the forms.
Malaria-species-specific antigens used in RDT tests
Some protein antigens are expressed only by specific malaria species; these antigens can therefore be used to identify these species. Two protein antigens that meet these criteria are widely employed in RDT assays. These are:
(1) Histidine-rich protein 2 (HRP2): An antigen that is specific for P.falciparum - Click for details of HRP2
(2) Detects lactate dehydrogenase epitopes that are specific for either P.falciparum or P.vivax Click for details of PfLDH or PvLDH
Malaria pan-specific antigens used in RDT tests
Other protein antigens are considered to be "pan specific". This means they are found in all malaria species that infect humans and can therefore be used to identify the presence of malaria, although without any species specificity. Again there are two protein antigens that are used for this purpose. These are:
(1) Detects forms of lactate dehydrogenase present on all malaria species (P.panLDH) Click for details of pan-malarial LDH
(2) Atigens on the parasite from enzyme aldolase that is found in all malarial species Click for details of pan-malarial aldolase
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