Patent ID: 8420353

Claim:
A process for preparing a humanized antibody consisting of the steps of: (a) first performing alanine scanning mutagenesis for replacing each amino acid residue in the entire complementarity determining region (CDR) of a murine monoclonal antibody variable regions that bind hepatitis B virus pre-S1 antigen with alanine to produce a series of transformants, selecting a transformant that has an affinity to antigen which is more than 3 times lower than the original murine antibody when replaced with alanine, determining the replaced amino acid residue of said transformant as a specificity determining residue (SDR), and (b) subsequently grafting all of the said SDRs to the corresponding amino acid sequence in human antibody heavy chain and light chain, wherein the CDR is selected from the group consisting of HCDR1(aa 31-35), HCDR2(aa 50-65) and HCDR3(aa 95-102) of the heavy chain (SEQ ID NO: 2); and LCDR1(aa 24-34), LCDR2(aa 50-56) and LCDR3(aa 89-97) of the light chain (SEQ ID NO: 4) of the murine monoclonal antibody variable regions, and wherein the SDR is the Trp33, Met34, and Asn35 of HCDR1; Arg50, Tyr52, and Pro52a of HCDR2; and Glu95, Tyr96, and Glu98 of HCDR3 of the murine monoclonal antibody KR127 heavy chain.