A STABLE VECTOR FOR HIGH-LEVEL EXPRESSION AND SECRETION OF HUMAN INTERFERON-ALPHA-A IN YEAST

Yeast high stable plasmid vector pHC11 was constructed by introducing pEM-BL Yi27 cleaved with SmaI into the SnaBI site of intact 2 mum plas mid. The result of plasmid stability assay revealed that 82% of the ho st cells still harbored the vector after 50-generations growth in non- selective medium, which confirmed the existence of a non-functional re gion in 2 mum plasmid. The human interferon alphaA (IFN alphaA) gene e xpression-secretion cassette was inserted into pHC11, and the yeast tr ansformant was cultured in complex medium. The data showed that the ex pressed product was 36.8% of the total protein amount in the culture s upernatant and the IFN alphaA biological activity was 2.6 x 10(10) uni ts per liter, demonstrating that high-level expression and secretion o f IFN alphaA were achieved in yeast by using the stable vector pHC11.