Rate of pESC plasmid loss in Saccharomyces cerevisiae in the absence of selective pressure (VAC13P.1126)

Abstract

Abstract Recombinant yeast has been proposed as a vaccine modality, especially for inducing CTL responses. The production of yeast expressing proteins of interest would be facilitated if they can be grown in less expensive non-selective medium. This would only be practical if the population of yeast retains high levels of plasmid over the duration of the growth. We tested the Saccharomyces cerevisiae multiple gene auxotroph with pESC-URA to determine the rate of plasmid loss in the population. The yeast maintain the plasmid much longer than anticipated, suggesting that growth in non-selective medium may be a viable method. Induction of protein expression increases the competitive advantage of plasmid loss. Growth rates of the yeast and of plasmid loss under these variable conditions was also determined.