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Histidine-rich protein 2 (HRP2): Difference between revisions

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|colspan="1" style = "font-size:140%; color:black; background: FFFAFA"|<span style="color:black>'''The HRP2 antigen - practicalities'''</span>
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<span style="font-size:90%">''P.falciparum'' parasites produce “histidine-rich” proteins (HRP). The HRP2 antigen is highly expressed and stable, and is therefore very useful in the detection of ''P.falciparum'' infection. Additionally, antibodies that detect HRP2 also cross react with the closely related HRP3 protein which can improve their sensitivity, particularly where there is HPR2 gene-deletion is not expressed.</br></br>At a high parasitaemia the sensitivity of HRP2 (like LDH-based tests) is likely to exceed 90% detection for ''P.falciparum''. However, at lower parasite levels (<1000 parasites/μL) the sensitivity will be significantly less (around 70%), although HRP2-based assays may still perform better than LDH-based assays in these circumstances.  
|colspan="1" style = "font-size:110%; color:black; background: FFFAFA"|<span style="color:navy>'''Use of HRP2 in diagnosis'''</span>
 
 
P.falciparum parasites produces “histidine-rich” proteins. The antigen is highly expressed and stable, and is therefore very useful in the detection of ''P.falciparum'' infection. Antibodies that detect HRP2 also cross react with the closely related HRP3 protein which can improve their sensitivity, particularly where HPR2 is not expressed.  
 
At a high parasitaemia the sensitivity of HRP2 (like LDH-based tests) will meet or exceed 90% detection for ''P.falciparum''. However, at lower parasite levels (<1000 parasites/μL) the sensitivity is significantly less (around 70% for HRP2, which may perform better than LDH at low parasite levels).  




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<span style="color:navy>'''Characteristics of HRP2 to be aware of'''</span>
<span style="font-size:90%"><span style="color:navy>'''Characteristics of HRP2 to be aware of'''</span></br></br>(1) Half-life: HRP2 has a long half-life ''in vivo'' and the antigen may persist in blood for some time following successful treatment. HRP2 should not therefore be used to monitor disease resolution (see sections on RDT ntepretation).</br>(2) HRP2 may be affected by false negative results when HRP2 antigen levels are very high in very severe infection (the prozone-like or postzone phenomenon - see description in the RDT-interpretation sections</br>(3) HRP2 is increasingly subject to gene deletion in some geographical areas* which may cause false negative results (see sections on RDT interpretation).</br></span>
 
 
(1) Half-life: HRP2 has a long half-life ''in vivo'' and expression persists following successful treatment. It should not therefore be used to monitor disease resolution [[Clearance of parasite antigen from blood|see antigen clearance after successful resolution]].</br>  
(2) HRP2 may be affected by the [[prozone effect]]</br>
(3) HRP2 is increasingly subject to [[HRP2 gene deletion|gene deletion]] in some geographical areas* which may cause false negative results.</br>

Latest revision as of 23:00, 17 March 2025

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>>>Current page: The HRP2 antigen

The HRP2 antigen - practicalities

P.falciparum parasites produce “histidine-rich” proteins (HRP). The HRP2 antigen is highly expressed and stable, and is therefore very useful in the detection of P.falciparum infection. Additionally, antibodies that detect HRP2 also cross react with the closely related HRP3 protein which can improve their sensitivity, particularly where there is HPR2 gene-deletion is not expressed.

At a high parasitaemia the sensitivity of HRP2 (like LDH-based tests) is likely to exceed 90% detection for P.falciparum. However, at lower parasite levels (<1000 parasites/μL) the sensitivity will be significantly less (around 70%), although HRP2-based assays may still perform better than LDH-based assays in these circumstances.


Characteristics of HRP2 to be aware of

(1) Half-life: HRP2 has a long half-life in vivo and the antigen may persist in blood for some time following successful treatment. HRP2 should not therefore be used to monitor disease resolution (see sections on RDT ntepretation).
(2) HRP2 may be affected by false negative results when HRP2 antigen levels are very high in very severe infection (the prozone-like or postzone phenomenon - see description in the RDT-interpretation sections
(3) HRP2 is increasingly subject to gene deletion in some geographical areas* which may cause false negative results (see sections on RDT interpretation).

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