Patent ID: 8440797

Claim:
An isolated anti-human CD81 antibody that binds to a peptide region consisting of the amino acid sequence of residues 80 to 175 in the amino acid sequence of SEQ ID NO: 22, wherein the binding affinity of the antibody to at least one human CD81 variant selected from the group consisting of the following (1) to (13) is less than 40% of that to the human CD81 polypeptide comprising the amino acid sequence of SEQ ID NO:22; (1) CD81 variant comprising the amino acid sequence of SEQ ID NO:22 except that tyrosine at residue 127 is substituted with phenylalanine or tryptophan; (2) CD81 variant comprising the amino acid sequence of SEQ ID NO:22 except that alanine at residue 130 is substituted with threonine or valine; (3) CD81 variant comprising the amino acid sequence of SEQ ID NO:22 except that valine at residue 135 is substituted with alanine or leucine; (4) CD81 variant comprising the amino acid sequence of SEQ ID NO:22 except that aspartic acid at residue 137 is substituted with alanine or glutamic acid; (5) CD81 variant comprising the amino acid sequence of SEQ ID NO:22 except that alanine at residue 143 is substituted with threonine or valine; (6) CD81 variant comprising the amino acid sequence of SEQ ID NO:22 except that histidine at residue 151 is substituted with alanine or arginine; (7) CD81 variant comprising the amino acid sequence of SEQ ID NO:22 except that leucine at residue 154 is substituted with alanine or isoleucine; (8) CD81 variant comprising the amino acid sequence of SEQ ID NO:22 except that glycine at residue 158 is substituted with alanine or serine; (9) CD81 variant comprising the amino acid sequence of SEQ ID NO:22 except that alanine at residue 164 is substituted with threonine or valine; (10) CD81 variant comprising the amino acid sequence of SEQ ID NO:22 except that serine at residue 168 is substituted with alanine or threonine; (11) CD81 variant comprising the amino acid sequence of SEQ ID NO:22 except that valine at residue 169 is substituted with alanine or leucine; (12) CD81 variant comprising the amino acid sequence of SEQ ID NO:22 except that leucine at residue 170 is substituted with alanine or isoleucine; and (13) CD81 variant comprising the amino acid sequence of SEQ ID NO:22 except that asparagine at residue 172 is substituted with alanine or glutamine.