Semiautomated design and soluble expression of a chimeric antigen TbpAB01 from Glaesserella parasuis

Pathogenic bacterial membrane proteins (MPs) are a class of vaccine and antibiotic development targets with widespread clinical application. However, the inherent hydrophobicity of MPs poses a challenge to fold correctly in living cells. Herein, we present a comprehensive method to improve the soluble form of MP antigen by rationally designing multi‐epitope chimeric antigen (ChA) and screening two classes of protein‐assisting folding element. The study uses a homologous protein antigen as a functional scaffold to generate a ChA possessing four epitopes from transferrin‐binding protein A of Glaesserella parasuis . Our engineered strain, which co‐expresses P17 tagged‐ChA and endogenous chaperones groEL‐ES, yields a 0.346 g/L highly soluble ChA with the property of HPS‐positive serum reaction. Moreover, the protein titer of ChA reaches 4.27 g/L with >90% soluble proportion in 5‐L bioreactor, which is the highest titer reported so far. The results highlight a timely approach to design and improve the soluble expression of MP antigen in industrially viable applications.