Surface antigen protein mutant of hepatitis b virus surface antigen

An oligo- or polypeptide comprising an amino acid sequence selected from the group consisting of:

• (a) an amino acid sequence which has at least 92% identity with SEQ ID No:
• 5;
• (b) an amino acid sequence in which zero to six amino acids in SEQ ID No:
• 5 are replaced, deleted or inserted;
• (c) an amino acid sequence which is a partial sequence of SEQ ID No:
• 3 having at least 5 or at least 6 or at least 7 or at least 8 or at least 9 or at least 10 or at least 11 or at least 12 or at least 13 or at least 14 or at least 15 consecutive amino acids of SEQ ID No:
• 3, where this partial sequence includes at least one of positions 100, 105, 110, 118, 120, 142, 160 and 173 of SEQ ID No:
• 3;
• and
• (d) a fragment of an HBs antigen of a hepatitis B virus, wherein (i) the fragment has a length of at least 5 or at least 6 or at least 7 or at least 8 or at least 9 or at least 10 or at least 11 or at least 12 or at least 13 or at least 14 or at least 15 amino acids, (ii) the HBs antigen has cysteine at position 100, arginine at position 105, leucine at position 110, arginine at position 118, leucine at position 120, leucine at position 142, asparagine at position 160 and proline at position 173, and (iii) the fragment comprises cysteine 100, arginine 105, leucine 110, arginine 118, leucine 120, leucine 142, asparagine 160 and/or proline 173.