<i>Escherichia Coli</i>-Based Cell-Free Protein Synthesis for Iterative Design of Tandem-Core Virus-Like Particles

• Main Authors: Noelle Colant, Beatrice Melinek, Stefanie Frank, William Rosenberg, Daniel G. Bracewell
• Format: Article
• Language: English
• Published: MDPI AG 2021-02-01
• Series: Vaccines
• Subjects: Cell-Free Protein Synthesis; Virus-Like Particle; Tandem-Core; Influenza Vaccine
• Online Access: https://www.mdpi.com/2076-393X/9/3/193

Tandem-core hepatitis B core antigen (HBcAg) virus-like particles (VLPs), in which two HBcAg monomers are joined together by a peptide linker, can be used to display two different antigens on the VLP surface. We produced universal influenza vaccine candidates that use this scaffold in an <i>Escherichia coli</i>-based cell-free protein synthesis (CFPS) platform. We then used the CFPS system to rapidly test modifications to the arginine-rich region typically found in wild-type HBcAg, the peptide linkers around the influenza antigen inserts, and the plasmid vector backbone to improve titer and quality. Using a minimal plasmid vector backbone designed for CFPS improved titers by at least 1.4-fold over the original constructs. When the linker lengths for the influenza inserts were more consistent in length and a greater variety of codons for glycine and serine were utilized, titers were further increased to over 70 μg/mL (4.0-fold greater than the original construct) and the presence of lower molecular weight product-related impurities was significantly reduced, although improvements in particle assembly were not seen. Furthermore, any constructs with the C-terminal arginine-rich region removed resulted in asymmetric particles of poor quality. This demonstrates the potential for CFPS as a screening platform for VLPs.