The recombinant BPV is constructed by ligating the insert and BPV vector (69%) onto the pBR 322 plasmid, thus generating the shuttle vector containing plasmid ori site and virus replication sequences.

These shuttle vectors are multiplied in E.coli cells first and then they are transformed into mouse cell line. It has been observed that if these sequences are removed prior to transfection, the vector exists at high copy number i.e., 200 copies per cell. When transfected with pBR 322 sequences, it exists at low copy number, i.e., less than 10 copies cell.

The major advantage of BPV is the generation of permanent cell line. As the infected cells are not killed, a stable plasmid number is found even when the insert is of large size.

The selection of transformants is very easy as they form a pile of cells on the transferred monolayer of cells called "Focus". The transformed cells are then selected by the presence of marker gene which is mostly the neomycin phospho transferase gene coding for resistance against G418.