EFFICIENT PRODUCTION OF ANTIBODY FRAGMENTS BY THE FILAMENTOUS FUNGUS TRICHODERMA-REESEI

We have engineered the filamentous fungus Trichoderma reesei to assemb le and secrete immunologically authentic engineered Fab antibody fragm ents into the culture medium. A major improvement in yield was achieve d by fusing the heavy Fd chain to the T. reesei cellulase, CBHI. The y ields of secreted, immunologically active Fab and CBHI-Fab fusion were 1 mg/l and 150 mg/l, respectively. The Fab fragment can be released f rom the fusion protein CBHI-Fab by an extracellular T reesei protease. There was no detectable difference in affinity for the antigen betwee n the engineered Fab and the idiotypic antibody.