A method for producing a human papillomavirus pseudovirion in a plant cell, the method comprising the steps of: (i) introducing into the plant cell: (a) a first nucleic acid encoding a HPV L1 polypeptide; and (b) a second nucleic acid encoding a HPV L2 polypeptide, wherein the first and second nucleic acids are contained on at least one expression vector, (c) a replicating vector derived from a geminivirus comprising an origin of replication (Ori) sequence recognised by a viral replication associated (Rep) protein, the replicating vector further comprising a third nucleic acid encoding a heterologous polypeptide, wherein the replicating vector is capable of undergoing rolling circle replication, and (d) a fourth nucleic acid encoding a Rep protein, wherein replication of the replicating vector is initiated by the Rep protein, and wherein the third nucleic acid is operably linked to a regulatory sequence which allows for the expression of the heterologous polypeptide in a mammalian cell; (ii) expressing the HPV L1 polypeptide and HPV L2 polypeptide and the Rep protein in the plant cell, and (iii) replicating the replicating vector from the Ori sequence recognised by the Rep protein in the plant cell, in order to produce a high copy number of a pseudogenome, wherein the pseudogenome is smaller than the replicating vector, is replicationally inert in mammalian cells in the absence of the Rep protein, and comprises the third nucleic acid, wherein the expressed HPV L1 and HPV L2 polypeptides assemble, together with a copy of the pseudogenome and encapsidate the pseudogenome to produce a HPV pseudovirion. (i) introducing into the plant cell: (a) a first nucleic acid encoding a HPV L1 polypeptide; and (b) a second nucleic acid encoding a HPV L2 polypeptide, wherein the first and second nucleic acids are contained on at least one expression vector, (c) a replicating vector derived from a geminivirus comprising an origin of replication (Ori) sequence recognised by a viral replication associated (Rep) protein, the replicating vector further comprising a third nucleic acid encoding a heterologous polypeptide, wherein the replicating vector is capable of undergoing rolling circle replication, and (d) a fourth nucleic acid encoding a Rep protein, wherein replication of the replicating vector is initiated by the Rep protein, and wherein the third nucleic acid is operably linked to a regulatory sequence which allows for the expression of the heterologous polypeptide in a mammalian cell; (a) a first nucleic acid encoding a HPV L1 polypeptide; and (b) a second nucleic acid encoding a HPV L2 polypeptide, wherein the first and second nucleic acids are contained on at least one expression vector, (c) a replicating vector derived from a geminivirus comprising an origin of replication (Ori) sequence recognised by a viral replication associated (Rep) protein, the replicating vector further comprising a third nucleic acid encoding a heterologous polypeptide, wherein the replicating vector is capable of undergoing rolling circle replication, and (d) a fourth nucleic acid encoding a Rep protein, wherein replication of the replicating vector is initiated by the Rep protein, and wherein the third nucleic acid is operably linked to a regulatory sequence which allows for the expression of the heterologous polypeptide in a mammalian cell; (ii) expressing the HPV L1 polypeptide and HPV L2 polypeptide and the Rep protein in the plant cell, and (iii) replicating the replicating vector from the Ori sequence recognised by the Rep protein in the plant cell, in order to produce a high copy number of a pseudogenome, wherein the pseudogenome is smaller than the replicating vector, is replicationally inert in mammalian cells in the absence of the Rep protein, and comprises the third nucleic acid,