Histidine-rich protein 2 (HRP2): Difference between revisions
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''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. | ''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) | 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 HP2-based assays may still perform better than LDH-based assays in these circumstances. | ||
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(1) Half-life: HRP2 has a long half-life ''in vivo'' and | (1) Half-life: HRP2 has a long half-life ''in vivo'' and the antigne may persist in blood for some time following successful treatment. HRP2 should not therefore be used to monitor disease resolution [[Clearance of parasite antigens from blood|see antigen clearance after successful resolution]].</br> | ||
(2) HRP2 may be affected by the [[prozone effect]]</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> | (3) HRP2 is increasingly subject to [[HRP2 gene deletion|gene deletion]] in some geographical areas* which may cause false negative results.</br> | ||
Revision as of 12:39, 2 October 2024
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| 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 HP2-based assays may still perform better than LDH-based assays in these circumstances.
Characteristics of HRP2 to be aware of
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