A Novel Peptide Aptamer to Detect Plasmodium falciparum Lactate Dehydrogenase

Alternative antibody (aptamer)-based biosensors are attracting increasing attention owing to advantages such as simplicity and low cost, which are beneficial for point-of-care diagnosis, particularly where resources are limited. In this study based on in silico modeling predictions made with Autodock Vina, the binding affinity of an optimized novel peptide (Pf_P1: KITTTDEEVEGIFD) was altered compared to that of the original epitope peptide (P1: KITDEEVEGIFDC). The binding energy of Pf_P1 implies that it has stronger interactions with Plasmodium falciparum lactate dehydrogenase (LDH) than with human LDH. Fluorescence-linked immunosorbent assay (FLISA) demonstrated significant interactions (P < 0.05) between the Pf_P1 peptide and P. falciparum LDH at 35.7 nmol. A peptide- and antibody-linked sandwich FLISA was able to detect at least 100 infected red blood cells (RBC)/μL significantly (P < 0.001). The clinical diagnostic performance of peptide- and antibody-linked sandwich FLISA was evaluated using blood samples from patients infected by P. falciparum with parasitemia values of 151 to 128,636. All positive samples exhibited higher fluorescence than normal samples did. In conclusion, in silico modeling was used to efficiently design a Plasmodium LDH epitope-derived peptide aptamer to function as an alternative to antibodies in immunoassays.