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RDT Test antigens: review of advantages and disadvantages
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Overview
One class of protein used to identify malaria serves very specific functions responsible for parasite behviour, and is not found in humans, as such this class of proteins are considered to be specific for the malaria parasite. The HRP2 antigen is an example of this class of proteins.
A second group represents proteins of metabolic pathways of both humans and malarial parasites, but with structural differences between humans and parasites. These different structural featues maen that they have antigenic features (epitopse) that allow them to be identified as plasmodium specific (plasmodium aldolase or pan-malarial LDH) or even specific for individual species (PfLDH and PvLDH). By combining these together, RDT tests can be designed to meet particular purposes.
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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