Nanobodies (Nb) are small antigen-recognizing proteins derived from the heavy chains of camelid antibodies. They can be generated by immunization of camelids followed by isolation of competent antibodies and sequencing of the variable domain. High affinity nanobodies are then selected by ELISA or similar techniques. Another strategy is the use of synthetic libraries such as yeast surface display platforms. Using the NbLib platform, we are developing nanobodies that bind the protein tyrosine phosphatase from S. pyogenes, SP-PTP. Our strategy involves enrichment of binding-competent Nbs from the library using magnetic-activated cell sorting followed by identification of high-affinity nanobodies by ELISA. These Nbs can be used as inhibitors of SP-PTP, a virulence factor in S. pyogenes, or as tools to probe their roles inside the bacteria or host cells.
