CHARACTERIZATION AND EVALUATION OF A RECOMBINANT HEPATITIS-B VACCINE EXPRESSED IN YEAST DEFECTIVE FOR N-LINKED HYPERGLYCOSYLATION

The hepatitis B (HB) virus preS2 + 2 polypeptide (the M or middle enve lope polypeptide) is N-glycosylated at the N4 residue of the preS2 dom ain when expressed in recombinant yeast. Hyperglycosylation at this am ino acid residue (the addition of a large number of mannose residues t o the core oligosaccharide), which occurs in common yeast strains, res ults in an HB vaccine with diminished immunogenicity. Hyperglycosylati on can be prevented by expressing the preS2 + S polypeptide in mutant yeast strains (e.g. mnn9) which limit N-linked glycosylation to the ad dition of only core saccharine residues. An HB vaccine prepared from r ecombinant yeast expressing the non-hyperglycosylated preS2 + 2 polype ptide was of similar immunogenicity in mice to a licensed HB vaccine a nd was much more immunogenic in humans than the hyperglycosylated preS 2 + 2 vaccine.