From filamentous phages

Many aspects of DNA replication in filamentous phages are similar to that of < >X 174. The unique property, release without cell killing, can be briefly discussed. The release from the cell occurs by a budding process in which the virus particle is always released from the cell with the end containing the A protein first. Interestingly, the orientation of the virus particle across the cell membrane is the same for its entry and exit from the cell. There is no accumulation of intracellular virus particles the assembly of mature virus particles occurs on the inner cell membrane and virus assembly is coupled with the budding process. 

Another viral chromosome that can be used as a vector is that of the filamentous phage Ml3. The M13 chromosome is a single-stranded DNA molecule which when inserted into the bacterial host replicates outside the bacterial chromosome in the cytoplasm. The virus is then reassembled and released from the bacterial cell without cell lysis. 

Ames RS, Tornetta MA, Jones CS, Tsui P, Isolation of neutralizing anti-C5a monoclonal antibodies from a filamentous phage monovalent Fab display library, J. Immunol., 152 4572-4581, 1994. 

Fig. 5.1. The principle of phage display is based on in vitro selection of peptides or proteins expressed at the surface of filamentous phages. In a biopanning experiment, specific binders can be captured from a library and their genes can be amplified by infection.

Crameri R, Blaser K Cloning allergens from Aspergillus fumigatus. The filamentous phage approach. Int Arch Allergy Immunol 1995 107 460-461. 

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