In this application is the expression and purification of a recombinantPlasmodium vivax (SalI) PvMSP-1 p42. The method of the present inventionproduces a highly purified protein which retains folding and disulfidebridging of the native molecule. The recombinant PvMSP-1 p42 is useful as adiagnostic reagent, for use in antibody production, and as a vaccine.