Mature Erythrocyte Surface Antigen Protein Identified in the Serum of Plasmodium falciparum-Infected Patients

Abstract

Abstract. This study was performed to identify circulating Plasmodium falciparum proteins in patient serum, which may be useful as diagnostic markers. Depletion of highly abundant proteins from each pooled serum sample obtained from P. falciparum-infected patients and healthy individuals was performed using the Proteoseek Antibody-Based Albumin/IgG Removal Kit (Thermo Scientific, Rockford, IL). In analysis 1, the depleted serum was analyzed directly by NanoLC-MS/MS. In analysis 2, the depleted serum was separated by two-dimensional electrophoresis followed by western blot analysis. Subsequently, the selected band was analyzed by NanoLC-MS/MS. The result of analysis 1 revealed the presence of two mature erythrocyte surface antigen (MESA) proteins and chloroquine resistance transporter protein (PfCRT). In addition, analysis 2 revealed an antigenic 75-kDa band when the membrane was probed with purified IgG from the pooled serum obtained from P. falciparum-infected patients. MS/MS analysis of this protein band revealed fragments of P. falciparum MESA proteins. Thus, in this study, two different analyses revealed the presence of Plasmodium MESA protein in pooled serum from malaria patients; thus, this protein should be further investigated to determine its usefulness as a diagnostic marker.

A Dual, Systematic Approach to Malaria Diagnostic Biomarker Discovery

“…Our review of malaria biomarkers summarized available evidence on novel biomarker candidates for malaria diagnosis but also revealed that few parasite proteins reported were selected as a result of an unbiased approach. Exceptions were mature erythrocyte surface antigen, glutamate-rich protein, and the P. vivax -specific proteins PVX_110940, PVX_083555, PVX_090265, PVX_003545, and PVX_094303, identified using high-throughput analysis techniques, for example, mass spectrometry [ 36 , 39 , 42 , 61 ]. These studies failed to describe the intrinsic diagnostic features of the identified candidates.…”