Simultaneous synthesis of two polypeptides of hepatitis B surface antigen directed by the promoter in Saccharomyces cerevisiae

The yeast Saccharomyces cerevisiae was t ransformed by an expression vector YAMTS, in which the and S regions of h u m a n hepatitis B virus were joined to the sequence encoding the promoter and leader region of the yeast mating pheromone a-factor. The HBsAg synthesized by yeast t rans formants contains two kinds of polypeptides: one encoded by the S region and the other encoded by the preS2-S region but with a higher molecular weight. The synthesized HBsAg also appears a s spherical particles under the electron microscope and h a s biophysical properties similar to the 22 nm particles found in the sera of hepatitis B patients. Key word: HBsAg; Recombinant DNA; Saccharomyces cerevisiae; Yeast a -factor promoter and leader sequence. Introduction (namely the Dane particle), which consists of a sur face envelope containing lipid and a core T h e worldwide impact of hepatitis B in which the viral DNA exists (Tiollais et al., infections has caused a serious problem in 1981). I n t he s e r a of hepatitis B patients, 22 nm public health. I n eastern Asia and tropical spherical particles, containing mainly hepatitis Africa more than 10% of t he population a r e B sur face ant igen (HBsAg), can also be found. chronic car r ie rs of HBV (Tiollais et al., 1985). I t ha s been demonstrated tha t HBsAg from The HBV virion is a particle of 42 nm i n diameter recombinant DNA technology can elicit HBsAg antibody in humans and in chimpanzees, Abbreviations: yeast alcohol dehydrogenase 1; promoter; Amp, ampicilin; HBsAg, and prevent t he vaccinated organisms from hepatitis B surface antigen; HBV, hepatitis B virus; contract ing HBV infection et al., kb, PB, phosphate Fur thermore , i t ha s been suggested tha t buffer, pH 7.4; PMSF, phenylmethyl sulfonylfluoride; gene, HBV gene coding 55 amino acids preceeding a n additional 55 amino acids encoded by the of the S gene; R, resistant; RIA, radioimmunoassay; region, if included, may increase t h e SDS, sodium dodecyl sulfate; S gene, HBV gene protective efficacy of vaccines. (Milich et encoding the surface antigen; YNB, yeast nitrogen base amino acids. 1985; Neura th et al., 1985).