Patent ID: 7135310

Claim:
A method of preparing an amplified product that is free of amplification primer sequences, said method comprising: (a) amplifying a target nucleic acid sequence encoding an antibody variable region or fragment of said variable region in an amplification reaction comprising: (i) a first primer that specifically anneals to a region upstream of a target polynucleotide sequence, wherein the first primer comprises a first restriction enzyme recognition site that is recognized by a first restriction enzyme that cleaves at a distance from the recognition site; and (ii) a second primer that specifically anneals to a region downstream of the target polynucleotide sequence, wherein the second primer comprises a second restriction enzyme recognition site that is recognized by a second restriction enzyme that cleaves at a distance from the recognition site; and (b) cleaving said amplified product with the first and second restriction enzymes, thereby obtaining the amplified product that is free of amplification primer sequences.