Rapid Assessment Of Fab-VHH Expression Application Of The Pfast™ Program For Early-Stage Titer And Activity Screening

When developing novel bi-specific antibody formats, expression optimization can make or break a program. This case study details the rapid development of a Fab-VHH fusion protein using the Pfast™ screening platform, demonstrating how systematic evaluation of expression parameters accelerates early-stage development. Working with a challenging bi-specific construct, researchers tested 40 different expression configurations across two gene orientations, ribosome binding site strengths, and 23 secretion leaders.

The light chain-first orientation emerged as the clear winner, delivering up to 570 μg/mL of soluble, active protein within just 10 days. Mass spectrometry confirmed correct assembly and leader sequence processing across top candidates, while activity assays validated functional binding. The approach eliminated months of iterative optimization, providing production-ready conditions for platform advancement.

Discover how high-throughput expression screening transforms complex antibody development timelines and de-risks manufacturing scale-up.