A phagemidic 12-mer peptide library (Ph.D.12 TM Phage Display Peptide Library, New England Biolabs Inc., Boston, MA, USA) was screened against PN-SIA 28 Fab fragment. Briefly, 300 ng of PN-SIA 28 were coated on four wells (96-wells plate, COSTAR), and the peptide library was amplified transforming electrocompetent E. coli XL1 Blue. 70 ml of the obtained phage preparation was incubated with PN-SIA 28 for 1 hour at 37uC and subsequently the unbound phages were removed by washing with PBS 1X-Tween20 using progressive Tween20 concentration starting from 0.1% to 0.5%. The phage that bound PN-SIA 28 was then eluted using low pH and, once neutralized, used to infect E. coli XL1 Blue for a subsequent ELISA screening on 100 ng/well coated PN-SIA 28. Positive clones were then sequenced using the kit-provided primers (New England Biolabs Inc., Boston, MA, USA).