Conserved regions of Plasmodium vivax potential vaccine candidate antigens in Sri Lanka: Conscious in silico analysis of prospective conformational epitope regions

Objective: To do mapping and modeling of conformational B cell epitope regions of highly conserved and protective regions of three merozoitecandidate vaccine proteins of Plasmodium vivax (P. vicar), ie. merozoite purface protein-1 (PvMSP-1), apical membrane antigen -1 domain II (PvAMA1-D II) and region II of the Duffy binding protein (PvDBP II), and to analyze the immunogenic properties of these predicted epitopes. Methods: 3 D structures of amino acid haplotypes from Sri Lanka (available in GeneBank) of PvMSP-1(19) (n=27), NAMA1-D II (n=21) and PvDBP II (n=33) were modeled. SEPPA, selected as the best online server was used for conformational epitope predictions, while prediction and modeling of protein structure and properties related to immunogenicity was carried out with Geno3D server, SCRATCH Protein Server, NetSmiP Server and standalonesoftware, Genious 5.4.4. Results: SEPPA revealed that regions of predicted conformational epitopes formed 4 clusters in PvMSP-I-19, and 3 clusters each in PLAMA1-D II and PvDBPII, all of which displayed a high degree of hydrophilicity, contained solvent exposed residues, displayed high probability of antigenicity and showed positive antigenic propensity values, that indicated high degree of immunogenicity. Conclusions: Findings of this study revealed and confirmed that different parts of the sequences of each of the conserved regions of the three selected potential vaccine candidate antigens of P. vivax are important with regard to conformational epitope prediction that warrants further laboratory experimental investigations in in vivo animal models.