Detection and growth kinetics of SV40 preparations with different enhancer element copy number

Abstract

It has been reported that the rate of growth of SV40 in certain cell culture systems is affected by the number of copies of the enhancer element, and that this might in turn affect the ability of manufacturers of poliovaccines to detect SV40 contamination in tests for adventitious agents. Eleven strains of SV40 of which three were primary isolates, three were control strains used in different laboratories and five were well characterised were examined for their enhancer copy number. It was found that the three primary isolates contained a single copy while three preparations used as controls in different laboratories were mixtures of single and multiple copy strains. The remaining five strains consisted of one known double enhancer and four known single enhancer strains. All eleven strains were titrated in BSC-1 cells. There was no correlation between the number of copies of the enhancer element and the rate of growth or the final titre reached, although there was variation between the strains.