CRISPR-Engineered Bacteriophage T4 for Foot-and-Mouth Disease Nanoparticle Vaccine Development.

Peptide-based vaccines offer a safer alternative to inactivated vaccines. However, the immunogenicity of the peptides is usually poor, and therefore, adjuvants or delivery systems are required. Bacteriophage T4, with its intrinsic immunostimulatory properties, provides a promising platform for antigen display. Here, we used CRISPR-Cas genome editing to insert a gene encoding a foot-and-mouth disease virus (FMDV) B-cell epitope (VP1130-158) into the C-terminus of the soc gene in the T4 genome. The T4 phage self-assembly system enables the display of epitopes on the capsid surface in vivo, generating VP1130-158-T4 virus-like particles. To further enhance immune activation, CD4⁺ T-cell epitopes FMDV 3A21-35 or tetanus toxoid P2830-844 were fused downstream of the VP1 epitope. These recombinant T4 phages provide proof-of-concept for the development of safe, epitope-based FMDV vaccines.