Oral immunization with a combination of Plasmodium yoelii merozoite surface proteins 1 and 4/5 enhances protection against lethal malaria challenge.

Oral immunization of mice with Escherichia coli-expressed Plasmodium yoelii merozoite surface protein 4/5 or the C-terminal 19-kDa fragment of merozoite surface protein 1 induced systemic antibody responses and protected mice against lethal malaria infection. A combination of these two proteins administered orally conferred improved protection compared to that conferred by either protein administered alone.