A recombinant VLP-antibody (VLP-Ab) comprising a modified hepadnaviral envelope fusion protein comprising an antibody variable domain. The variable domain may be selected from an antibody heavy chain variable domain and a light chain variable domain. In some embodiments, the variable domain (the first variable domain) is bound to a complementary antibody variable domain of a second variable domain protein and forms the antibody antigen binding site specific for a target molecule. One second variable domain protein may be a modified hepadnaviral envelope fusion protein comprising a complementary antibody variable domain. The VLP-Ab may comprises a modified hepadnaviral envelope fusion protein comprising a heterologous antigen. One modified hepadnaviral envelope fusion protein is a hepatitis B envelope protein or a VLP-forming part or variant thereof. A eukaryotic expression vector comprising a recombinant nucleic acid molecule encoding a hepadnavirus envelope-antibody fusion protein comprising an antibody variable domain wherein the variable domain is selected from an antibody heavy chain variable domain and a light chain variable domain. A eukaryotic expression vector comprising a recombinant nucleic acid molecule encoding a second variable domain protein comprising an antibody variable domain wherein the variable domain is selected from an antibody heavy chain variable domain and a light chain variable domain. The expression vector may encode a single variable domain selected from an antibody heavy chain variable domain and a light chain variable domain. The expression vector may encode an Sc Fv. A eukaryotic expression vector operably linked to a polynucleotide encoding a hepadnavirus envelope-antibody fusion protein comprising and an antibody variable domain (EAFP) wherein the antibody variable domain is selected from an antibody heavy chain variable domain and a light chain variable domain, and further capable of expressing a second polynucleotide encoding a sec
