CRISPR-Editing of the Vero Cell Line Improves Processability of Live Virus Vaccines by Enabling Targeted Proteolysis of Fibronectin.

Removal of host cell components is a significant cost driver in the production of live virus vaccines. Filtration processes such as tangential flow filtration can be effective in this capacity by leveraging the relative size difference between viral particles and host proteins; however, filtration membranes can be fouled by larger proteins, particularly those of the extracellular matrix. In this study, we used CRISPR editing to insert the recognition element of the highly-selective TEV protease into various positions of the gene encoding fibronectin in the genome of the Vero cell line, a common platform for viral production. By screening edited cell lines, we identified a promising candidate line in which fibronectin could be effectively removed by treating with the protease during processing, eliminating filter fouling and allowing for viral purification without the need for costly chromatography steps.