Merozoite surface protein families are attractive malaria vaccine targets given their functional importance and accessibility to serum antibodies. Among them is merozoite surface protein-8, which contains two epidermal growth factor-like domains that are structurally and/or functionally conserved among species of Plasmodium. We have shown that immunization with refolded recombinant Plasmodium yoelii MSP-8 protects BALB/c mice against a P .yoelii 17XL challenge infection. My thesis focus is to further characterize the mechanism underlying the protection that is induced by PyMSP-8 immunization and to explore the function of MSP-8 in the parasite life cycle. So far, we have shown that such protection is largely B cell dependent and correlates with the induction of antibodies that recognize disulfide-bond-dependent epitopes of PyMSP-8. We have also shown that PyMSP-8 binds to the surface of uninfected mouse RBCs, suggesting a possible role of MSP-8 in parasite invasion of the red blood cell.