The present invention relates to a novel lipoprotein particle, methods for preparing and purifying the same, its use in medicine, particularly in the prevention of malarial infections, compositions/vaccines containing the particle or antibodies against the protein particle such as monoclonal or polyclonal antibodies and use of the same, particularly in therapy. Furthermore, particles with the specific ratio can be prepared by employing yeast, Saccharomyces cerevisiae or Pichia pastoris. In particular it relates to an immunogenic protein particle comprising the following monomers:a. a fusion protein comprising sequences derived from a CS protein of P. vivax and the S antigen of Hepatitis B (CSV-S), andb. S antigen derived from Hepatitis B virus,and characterized in that the ratio of S to CSV-S is in the range 0.1 to 1. Suitably, the ratio of S to CSV-S is in the range 0.19 to 0.30 or 0.68 to 0.80.
