Identification of Plasmodium knowlesi Merozoite Surface Protein-1 19 (PkMSP-1 19 ) novel binding peptides from a phage display library

Plasmodium knowlesi, the fifth human malaria parasite, has caused mortality in humans. We aimed to identify P. knowlesi novel binding peptides through a random linear dodecapeptide phage display targeting the 19-kDa fragment of Merozoite Surface Protein-1 protein. rPkMSP-1 protein was heterologously expressed using Expresso Solubility and Expression Screening System and competent E. cloni 10G cells according to protocol. Three rounds of biopanning were performed on purified rPkMSP-1 to identify binding peptides towards rPkMSP-1 using Ph.D.™-12 random phage display library. Binding sites of the identified peptides to PkMSP-1 were in silico predicted using the CABS-dock web server. Four phage peptide variants that bound to PkMSP-1 were identified after three rounds of biopanning, namely Pkd1, Pkd2, Pkd3 and Pkd4. The sequences of both Pkd1 and Pkd2 consist of a large number of histidine residues. Pkd1 showed positive binding signal with 6.1× vs. BSA control. Docking results showed that Pkd1 and Pkd2 were ideal binding peptides for PkMSP-1 . We identified two novel binding peptides of PkMSP-1 , Pkd1 (HFPFHHHKLRAH) and Pkd2 (HPMHMLHKRQHG), through phage display. They provide a valuable starting point for the development of novel therapeutics.