High-Level Expression, Purification and Characterization of A Recombinant Plasmodium vivax Apical Membrane Antigen 1: Implication for vivax Malaria Vaccine Development

Objective: the apical membrane antigen-1 (ama-1) is considered as a promising candidatefor development of a malaria vaccine against plasmodium parasites. the correctconformation of this protein appears to be necessary for the stimulation of parasite-inhibitoryresponses, and these responses, in turn, seem to be antibody-mediated. therefore, inthe present investigation, we expressed the plasmodium vivax ama-1 (pvama-1) ectodomainin escherichia coli (e. coli), purified it using standard procedures and characterizedit to determine its biological activities for it to be used as a potential target for developinga protective and safe vivax malaria vaccine.materials and methods: in this experimental investigation, the ectodomain of pvama-1 antigen (genbank accession no. jx624741) was expressed in the e. coli m15-pqe30 expression system and purified with immobilized-metal affinity chromatography.the correct conformation of the recombinant protein was evaluated by westernblotting and indirect immunofluorescence antibody (ifa) test. in addition, the immunogenicproperties of pvama-1 were evaluated in balb/c mice with the purified proteinemulsified in freund’s adjuvant.results: in the present study, the pvama-1 ectodomain was expressed at a high-level(65 mg/l) using a bacterial system. reduced and non-reduced sodium dodecyl sulfate-polyacrylamide gel electrophoresis (sds-page) as well as western blot analysisconfirmed the appropriate conformation and folding of pvama-1. the evaluation ofimmunogenic properties of pvama-1 showed that both t helper-1 and 2 cells (th1and th2) responses were present in mice after three immunizations and persisted upto one year after the first immunization. moreover, the antibodies raised against therecombinant pvama-1 in injected mice could recognize the native protein localized onp. vivax parasites.conclusion: we demonstrate that our recombinant protein had proper conformationand folding. also, there were common epitopes in the recombinant forms correspondingto native proteins. these results; therefore, indicate that the expressed pvama-1has the potential to be used as a vivax malaria vaccine.