SV40 Virus Expression Vectors

This chapter discusses the characteristics of Simian virus 40 (SV40) infection and the use of various types of SV40-derived virus vectors. Advantages and disadvantages of early- or late-replacement vectors are presented. The chapter discusses types of experiments in which recombinant SV40 vectors have proven useful, followed by protocols for preparation, titration, and storage of high-titer virus stocks. Examples of the assays to which this vector system is well suited are presented in the chapter. The ease with which high titer SV40 virus stocks can be made and stored for long periods allows infecting an entire population of cells reproducibly at a multiplicity high enough that the time course of protein expression is quite predictable. SV40 vectors have been made by replacing either the early or the late genes of the virus with an exogenous gene. In the case of early-replacement vectors, the late genes encoding the capsid proteins are present and the virus capsid is merely being used as an effective plasmid delivery system. Recombinant SV40 stocks are titered by immunofluorescence with an antibody specific for the exogenous protein to be expressed. The immunofluorescence assay is fast and measures the parameter of interest: the expression of the exogenous gene.