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'''Malaria-species-specific antigens used in RDT tests'''</br></br>
 
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:</br></br>
<span style="font-size:90%">'''Overview'''</br></br>Several forms of malarial protein may be used to identify malaria based on their expression or structure. For example, the HRP2 protein used to identify ''Plasmodium falciparum'' has specific functions for that parasite and HRP2 is not found in other malarial species (or humans) so has high specificity for the diagnosis of ''P.falciparum''. Other proteins are outwardly less specific, with the major examples forming part of metabolic pathways active in both humans and malaria (lactate dehydrogenase and aldolase). However, for these proteins there are clear structural differences between human and parasite forms of these proteins, and in some cases also between the different malarial species. These different structural featues give rise to antigenic epitopses that can be used to identify malarial parasites as a group (pan-malarial antigens) or distinguish different malarial species (species specific antigens).</br></br></span>
(1) Histidine-rich protein 2 (HRP2): An antigen that is specific for ''P.falciparum'' - [[Histidine-rich protein 2 (HRP2)|Click for details of HRP2]]</br>
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(2) Forms of lactate dehydrogenase that are specific for either ''P.falciparum'' or ''P.vivax''  [[Species-specific forms of lactate dehydrogenase (PfLDH and PvLDH)|Click for details of PfLDH or PvLDH]]</br></br></br>
<span style="font-size:90%">'''Malaria-species-specific antigens'''</br></br>These are expressed only by specific malaria species; and can therefore be used to identify these species. Two malaria-specific antigens are widely employed in RDT assays. These are:</br></br>(1) Histidine-rich protein 2 (HRP2): An antigen that is specific for ''P.falciparum'' - [[Histidine-rich protein 2 (HRP2)|Click for details of HRP2]]</br>(2) Detects lactate dehydrogenase epitopes that are specific for either ''P.falciparum'' (PfLDH) or ''P.vivax'' (PvLDH) [[Species-specific forms of lactate dehydrogenase (PfLDH and PvLDH)|Click for details of PfLDH or PvLDH]]</br></br></br>'''Malaria pan-specific antigens used in RDT tests'''</br></br>Protein antigens found in all malaria species (but not humans) are called "pan specific". This means they can be used to identify the presence of malaria, although without any species specificity. There are two protein main antigens that are used for this purpose. These may:</br></br>(1) Lactate dehydrogenase epitopes that are present on all malaria species (pan-malarial LDH or pLDH)</br>(2) Aldolase epitopes found in all malarial species but not humans (pan-malarial aldolase)
'''Malaria-species-specific antigens used in RDT tests'''</br></br>
 
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:</br></br>
<span style="font-size:90%">[[pan-malarial LDH and Adolase|Click for details of pan-malarial LDH and aldolase]]</br>
(1) Plasmodium lactate dehydrogenase: tests recognise protein antigens (epitopes) present on LDH in all species (pan-malarial LDH) [[pan-malarial LDH|Click for details of pan-malarial LDH]]</br>
(2) Atigens on the parasite from enzyme aldolase that is found in all malarial species [[pan-malarial aldolase|Click for details of pan-malarial aldolase]]</br>

Latest revision as of 23:00, 17 March 2025

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RDT Test antigens: review of advantages and disadvantages


Overview

Several forms of malarial protein may be used to identify malaria based on their expression or structure. For example, the HRP2 protein used to identify Plasmodium falciparum has specific functions for that parasite and HRP2 is not found in other malarial species (or humans) so has high specificity for the diagnosis of P.falciparum. Other proteins are outwardly less specific, with the major examples forming part of metabolic pathways active in both humans and malaria (lactate dehydrogenase and aldolase). However, for these proteins there are clear structural differences between human and parasite forms of these proteins, and in some cases also between the different malarial species. These different structural featues give rise to antigenic epitopses that can be used to identify malarial parasites as a group (pan-malarial antigens) or distinguish different malarial species (species specific antigens).

Malaria-species-specific antigens

These are expressed only by specific malaria species; and can therefore be used to identify these species. Two malaria-specific 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 (PfLDH) or P.vivax (PvLDH) Click for details of PfLDH or PvLDH


Malaria pan-specific antigens used in RDT tests

Protein antigens found in all malaria species (but not humans) are called "pan specific". This means they can be used to identify the presence of malaria, although without any species specificity. There are two protein main antigens that are used for this purpose. These may:

(1) Lactate dehydrogenase epitopes that are present on all malaria species (pan-malarial LDH or pLDH)
(2) Aldolase epitopes found in all malarial species but not humans (pan-malarial aldolase)

Click for details of pan-malarial LDH and aldolase
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