Patent ID: 7399594

Claim:
A method for producing a hybrid antibody or hybrid antibody fragment comprising: providing an initial antibody having specificity for a target; determining the sequence of a variable region of the initial antibody; and (i) selecting a first component of the variable region selected from the group consisting of FR1, FR2 and FR3; comparing the sequence of the first component of the variable region to sequences contained in a reference database of antibody sequences or antibody fragment sequences from a target species; selecting a first framework sequence from the database which is one of the top one hundred hits based on sequence homology to the first component; determining which germline gene family the first framework sequence was derived from; (ii) selecting a second component of the variable region which is different than the first component, the second component selected from the group consisting of FR1, FR2 and FR3; comparing the sequence of the second component to sequences contained in a reference database of antibody sequences or antibody fragment sequences from the target species; selecting a second framework sequence from the database which is one of the top one hundred hits based on sequence homology to the second component and which corresponds to the same germline gene family as the first framework sequence selected from the database in step (i), wherein the first and second framework sequences selected from the reference database are from different antibodies; and (iii) operatively linking the selected framework sequences to the CDRs and unselected framework sequences of the initial antibody to produce a hybrid antibody or hybrid antibody fragment that has specificity for said target, wherein the framework sequences and CDRs are linked together in the following arrangement: FR1-CDR1-FR2-CDR2-FR3-CDR3-FR4.