PfHPRT: a new biomarker candidate of acute Plasmodium falciparum infection.

Plasmodium falciparum is a protozoan parasite that causes human malaria. This parasitic infection accounts for approximately 655,000 deaths each year worldwide. Most deaths could be prevented by diagnosing and treating malaria promptly. To date, few parasite proteins have been developed into rapid diagnostic tools. We have combined a shotgun and a targeted proteomic strategy to characterize the plasma proteome of Gambian children with severe malaria (SM), mild malaria, and convalescent controls in search of new candidate biomarkers. Here we report four P. falciparum proteins with a high level of confidence in SM patients, namely, PF10_0121 (hypoxanthine phosphoribosyltransferase, pHPRT), PF11_0208 (phosphoglycerate mutase, pPGM), PF13_0141 (lactate dehydrogenase, pLDH), and PF14_0425 (fructose bisphosphate aldolase, pFBPA). We have optimized selected reaction monitoring (SRM) assays to quantify these proteins in individual patients. All P. falciparum proteins were higher in SM compared with mild cases or control subjects. SRM-based measurements correlated markedly with clinical anemia (low blood hemoglobin concentration), and pLDH and pFBPA were significantly correlated with higher P. falciparum parasitemia. These findings suggest that pHPRT is a promising biomarker to diagnose P. falciparum malaria infection. The diagnostic performance of this marker should be validated prospectively.