Abstract: The invention relates to chimeric proteins comprising an antigen and a trimer forming portion or a trimer and virus-like particle forming portion of foamy virus envelope protein (FV TM). The trimer or trimer and virus-like particle forming portion comprises i) full length foamy virus transmembrane protein; ii) foamy virus transmembrane protein absent a functional cytoplasmic domain; iii) foamy virus transmembrane protein absent a functional cytoplasmic domain and transmembrane domain; iv) foamy virus ectodomain comprising N-terminal heptad repeat region and cysteine rich region between N-terminal heptad repeat region and C-terminal ?-helical region; v) N-terminal heptad repeat region; vi) a functional variant of any one of i) to v); or vii) any one of i) to vi) lacking an FV fusion peptide domain. In particular, the antigen is an antigen of a virus envelope protein, such as HIV gp 120.

Abstract: The present invention provides a virus-like particle (VLP) comprising i) a polypeptide comprising a polypeptide of interest (POI) and at least a particle-associating portion of a large envelope (L) polypeptide of an avian hepadnavirus or a functional derivative or homolog thereof, and ii) a small envelope (S) polypeptide of an avian hepadnavirus or a functional derivative or homolog thereof. By introducing one or more POIs into the L polypeptide, the POI is translocated along with L into a particle structure made up primarily of S polypeptide. The present invention furthermore provides methods for producing a recombinant virus-like particle.