Large-scale purification and characterization of malaria vaccine candidate antigen Pvs25H for use in clinical trials.

The budding yeast Saccharomyces cerevisiae has been used to express the recombinant protein Pvs25H, currently the only candidate transmission-blocking vaccine against Plasmodium vivax malaria. This molecule contains four epidermal growth factor-like domains and is expressed as at least two stable monomeric forms with different physicochemical properties. Pvs25H-A is apparently homogeneous and seems to have a correct disulfide bond structure. By contrast, Pvs25H-B is produced as a heterogeneous population of molecules, some of which are associated with an as yet unidentified chromophore, and it contains both internal and N-terminal cleavages. We report here a procedure for successfully separating these two forms with a process suitable for clinical production of this antigen. Copyright 2002 Elsevier Science (USA).