pfhrp2

pfhrp2 stands for the Plasmodium falciparum histidine-rich protein 2 gene. It encodes the PfHRP2 protein, a histidine-rich antigen produced by the malaria parasite during infection and released into the host’s blood. PfHRP2 is a common target in many malaria rapid diagnostic tests (RDTs) because it is abundantly expressed by P. falciparum, enabling rapid field-based detection of infection.

In diagnostic practice, HRP2-based RDTs detect PfHRP2 antigen in blood samples to indicate P. falciparum malaria. These tests are valued for their speed, simplicity, and suitability for low-resource settings. Sensitivity can vary with parasite density and with HRP2 expression levels. A limitation is the persistence of PfHRP2 in the bloodstream after parasite clearance, which can yield false-positive results for a period following treatment. Cross-reactivity with related proteins, such as PfHRP3, can affect interpretive accuracy in some tests, and not all HRP2-based assays detect non-falciparum species.

Genetically, pfhrp2 is located in the Plasmodium falciparum genome and exhibits variability in its repeat-rich sequence. Importantly, some parasite strains carry deletions or disruptions of pfhrp2, which can lead to false-negative HRP2 test results. pfhrp2 deletions have been reported in multiple regions and pose a challenge to relying solely on HRP2-based diagnostics in those areas. In response, public health guidance emphasizes surveillance for pfhrp2 deletions and, where deletions are prevalent, the use of non-HRP2 antigens (such as pLDH or aldolase) in RDTs or complementary diagnostic methods.

See also: pfhrp3, malaria rapid diagnostic tests, HRP2 antigen.