Methods of affinity maturing antibodies

1. A method of affinity maturing an antibody, comprising the steps of:

a. obtaining an amino acid sequence of the antibody light chain variable region (VL) or the antibody heavy chain variable region (VH);

b. identifying rSDRU residues in the amino acid sequence of the antibody VL or VH;

c. selecting a subset of the rSDRU residues to be diversified;

d. selecting a set of amino acids or a universal set of amino acids used for diversifying the subset of the rSDRU residues;

e. preparing a library of antibody VL or VH variants by diversifying the subset of the rSDRU residues selected in step c. with the set of amino acids selected in step d.;

f. expressing the library of antibody VH or VL variants in a host or translating the library of antibody VH or VL variants in vitro; and

g. selecting from the library of antibody VH or VL variants one or more affinity matured antibody having an improved affinity to an antigen, wherein the rSDRU residues to be diversified comprise the antibody VL Chotia residues 30a, 30c, 30d, 30f, 32, 50, 91, 92, 93, 94, and 96.

2. The method of claim 1 , wherein the subset of the rSDRU residues comprises residues having rSDRU>5, rSDRU>15, rSDRU>30, rSDRU>40, or rSDRU>60.

3. The method of claim 1 , wherein the subset of the rSDRU residues comprises residues having rSDRU>40.

4. The method of claim 1 , wherein Trp, Asn or Ser is removed from the set of amino acids or from the universal set of amino acids.

5. The method of claim 1 , wherein the universal set of amino acids is RNDGHSWY, RNDGHSY, RNDGHWY, or RDGHSWY.

6. The method of claim 1 , wherein the set of amino acids in step d) comprise

a. RNDGHSY at VL Chothia residue 30;

b. RNDGHWY at VL Chothia residue 30a;

c. RNDGHSY at VL Chothia residue 30c;

d. RNDGHWY at VL Chothia residue 30f;

e. RNDY at VL Chothia residue 32;

f. YWNK at VL Chothia residue 50;

g. SYGH at VL Chothia residue 91;

h. SYGN at VL Chothia residue 92;

i. STER at VL Chothia residue 93;

j. YSHT at VL Chothia residue 94; and

k. YRWL at VL Chothia residue 96.