Hepatitis B vaccine

#This invention relates to recombinant DNA molecules which code for polypeptides having specificity towards a hepatitis B viral antigen.

#More particularly this invention relates to a vaccine composition for stimulating the production of antibodies in humans to a variant hepatitis B virus.

#The cloning of the genomes of hepatitis B virions of different serotypes is well known in the art (Miller et al). Dane particles which are hepatitis B virions and are isolatable from infected patients have a diameter of approximately 42 nm. Each consists of an envelope comprising the hepatitis B surface antigen (HBsAg), a capsid (HBcAg), an endogenous polymerase and a DNA genome. A third polypeptide, `e` antigen (HBeAg) is made by the hepatitis B virus and found in solubilized form in serum.

#FIG. 1 illustrates serial serum aminotransferase (ALT) levels from Patient No. 1. Normal levels are below 40 i.mu./L. Serum HBV markers were measured at various prints in time. In August 1992 HBV DNA was found by PCR yet HBsAg and the other HBV markers were undetected.

#FIG. 2 illustrates serial serum ALT levels from Patient No. 2 as well as serum hepatitis B virus markers. Abbreviations indicate: w, wild type; m, mutant.

#FIG. 3 is a diagrammatic representation of the surface gene open reading frame, position of the PCR and sequencing primers, and the overlapping polymerase open reading frame (P ORF). Shaded circles represent initiation and stop codons, whereas the shaded box indicates the insertion hot spot in relation to the `a` determinant (positions 522-593). The nucleotide numbering is from a hypothetical EcoRI site as in published HBV DNA sequences, because the present isolates did not possess an EcoRI site.

#HBV mutations are more commonly found in particular areas of the sequence characterised by runs of bases. In the case under study the insertion is associated with a run of four adenines. This area is seemingly a "hot spot" for insertion in some isolates from Chinese HBsAG negative HBV carriers.

#In a further aspect of the invention there is provided a process for preparing the mHBsAg and the vaccine composition obtained therefrom.

#Preferably the mHBsAg is obtained synthetically, either by peptide synthesis or more preferably by recombinant DNA techniques.