Detection of histidine-rich protein 2- and/or 3-deleted Plasmodium falciparum using the automated hematology analyzer XN-31: A proof-of-concept study.

Abstract

Rapid diagnostic tests (RDTs) based on immunochromatographic detection of Plasmodium falciparum histidine-rich protein 2 (HRP2) have been frequently used for malaria diagnosis. The HRP2-based RDTs are highly sensitive and easy to use; however, their sensitivity may be low in detecting P. falciparum strains carrying deletion of the pfhrp2 and pfhrp3 genes encoding HRP2 and HRP3, respectively. The automated hematology analyzer XN-31, developed by Sysmex (Kobe, Japan) to aid in malaria diagnosis, has higher sensitivity than RDTs owing to a unique automated nucleic acid staining technology that has shown great potential in clinical settings. In this study, we compared the performance of the XN-31 analyzer and two RDTs to detect pfhrp2- and/or pfhrp3-deleted parasites cultured in vitro. The analyses showed that the analyzer was not only as sensitive to pfhrp2- and/or pfhrp3-deleted strains as it was to the wild-type strain but also had higher sensitivity than the RDTs. These results suggested that the XN-31 analyzer is useful for rapid and reliable detection of pfhrp2- and/or pfhrp3-deleted parasites in clinical settings.