Abstract: The specification discloses chimeric or recombinant virus-like particles comprising (i) S polypeptide of an avian hepadnavirus and (ii) a chimeric fusion protein comprising a polypeptide of interest covalently attached to a particle-associating portion of L polypeptide of an avian hepadnavirus, wherein the polypeptide of interest comprises a transmembrane domain or a protein binding domain or motif and wherein the chimeric fusion protein further comprises a second or further polypeptide of interest comprising a transmembrane domain and/or a protein binding domain or motif, wherein the second or further polypeptide is associated with the virus-like particle via non-peptide bonds. It is proposed that such VLPs more closely resemble the naturally occurring configuration of antigenic complexes or pathogens. The chimeric virus-like particles are illustrated using viral envelope proteins from measles, hepatitis C virus, influenza A and HIV and by polyproteins from Plasmodium surface proteins.

Abstract: An immunogenic polypeptide for use in inducing an immune response against Plasmodium infection comprises an amino acid sequence corresponding to a non-full length fragment of the apical membrane antigen 1 (AMA-1) of Plasmodium species which does not include a transmembrane domain thereof, and which is stabilised by folding thereof. Production of the immunogenic polypeptide by expression of a recombinant DNA molecule in a host cell, and methods and compositions using the immunogenic polypeptide are disclosed.