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RDT Test antigens: review of advantages and disadvantages
Overview
Several forms of malarial protein may be used to identify malaria. One protein serves a very specific function within the Plasmodium falciparum parasite, and is therefore very useful in the diagnosis P.falciparum - not being found in other malarial species (or humans). Other diagnostic proteins are outwardly less specific, being found in the metabolic pathways of both humans and malarial parasites. However, there are clear structural differences between human and parasite forms of these proteins, andin some cases also between the different malarial species. These different structural featues give rise to antigenic epitopses that can be used to identify malaria infections by all species, or for some antigenic epitopes can distinguish different malarial species.
Malaria-species-specific antigens
These are expressed only by specific malaria species; and can therefore be used to identify these species. Two such protein antigens 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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