Rapid discovery and optimization of therapeutic antibodies against emerging infectious diseases

Rogers, J.; Schoepp, R.J.; Schröder, O.; Clements, T.L.; Holland, T.F.; Li, J.Q.; Li, J.; Lewis, L.M.; Dirmeier, R.P.; Frey, G.J.; Tan, X.; Wong, K.; Woodnutt, G.; Keller, M.; Reed, D.S.; Kimmel, B.E.; Tozer, E.C.

Screening of these libraries was accomplished using a novel high throughput DNA display methodology (Fig. 1 ). This technique involves the intracellular expression of a Fab fragment as a fusion protein with a zinc finger. Because the zinc finger binds to its corresponding DNA binding domain on the plasmid, the fusion protein binds to the DNA encoding its genotype. Following cell lysis, this complex is panned against the antigen of interest. The fusion protein -plasmid complex was found to be extremely stable by Biacore analysis (data not shown) with a half-life of $9 h at room temperature. Also of note, tests were done to ensure that no plasmid switching occurred at this time (i.e. the complex dissociating and the fusion protein binding to the wrong plasmid). Multiple separate screens were performed using Dynal beads coated with the spike protein, whole viral isolates, and infected cell lysates as antigens.