Cloning and expression of single chain antibody fragments in Escherichia coli and Pichia pastoris

The potential of recombinant antibody fragments is likely to be fulfilled o nly if they can be produced routinely at high concentrations. We have compa red the ability of Escherichia coli and Pichia pastoris to produce function al recombinant single chain antibody (scAb) fragments. Two scAb fragments w ere expressed, an antihuman type V acid phosphatase (TRAP) and an anti-Pseu domonas aeruginosa lipoprotein I. We report here that, while expression fro m P. pastoris resulted in a significantly increased level of expression of the anti-TRAP scAb compared to E. coli, neither fragment was able to bind i ts target antigen as well as the bacterial product.