Purified F1-and V-proteins were either coated directly to Maxisorp plates (Nunc, Denmark) in PBS buffer at 4uC, overnight for plate format panning or were biotin-labeled first with EZ-link Sulfo-NHS-LC-Biotin (Pierce, Rockford, IL) for streptavidinconjugated magnetic bead format panning. The labeling was performed according to the manufacture's recommended protocol. For the plate format, approximately 10 12 Fabs displayed on the surface of phage amplified from a large naive library [35] were suspended in PBS with 2% dry milk and applied to wells coated with the F1-or V-proteins. After incubating for 2 hours at room temperature, each well was washed 5 times for the first round and 10 times for the subsequent four rounds before the phage were rescued with TG1 cells at the exponential growth phase. For the bead format, biotin-labeled F1-and V-antigens were first incubated with the same amount of phage as in the plate format in 1 ml of PBS+2% dry milk suspension at room temperature for 2 hour. Fifteen ml of Dynabeads MyOne Streptavidin T1(Invitrogen Dynal AS, Oslo, Norway) pre-blocked with PBS+2% dry milk was then added to the antigen/phage mixture for one hour at room temperature. The beads were then washed 5 times with PBS for the first round and 10 times for the subsequent four rounds of selection. Phage were then rescued with TG1 cells. A total of four rounds were performed for each antigen with each format.