Simian virus 40 (SV40)-based shuttle vectors, containing the SV40 late genes, can be packaged as infectious pseudovirions. In terms of their function as bacterial plasmids, modifications in the overall size of these plasmids can be tolerated within a very wide range, which has allowed us to determine the requirements for SV40 encapsidation, free of the more stringent limitations of SV40 virus. Monkey COS7 cells were transfected with over- and undersized SV40-based shuttle virus plasmids and their progeny have been analysed to follow the stability and evolution of these genomes. Two of the three plasmids analysed undergo recombination, generating molecules with sizes of between 4·0 and to 4·8 kb which were selected after multiple lytic cycles. This size range may correspond to the DNA lengths preferentially packaged in SV40 capsids. The structure of the rearranged plasmids indicates that there is a strong selective pressure for genomes that retain the functions necessary for replication and virus production. Depending on the parent DNA, two main classes of rearrangements were generated: duplications in tandem with the SV40 origin of replication and deletions. Both classes are probably a result of selective size and replicative advantages, which are then biologically amplified during plasmid transmission as virus particles.


Article metrics loading...

Loading full text...

Full text loading...


Most cited this month Most Cited RSS feed

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error