Building and optimizing a virus-specific T cell receptor library for targeted immunotherapy in viral infections

Restoration of antigen-specific T cell immunity has the potential to clear persistent viral infection. T cell receptor (TCR) gene therapy can reconstitute CD8 T cell immunity in chronic patients. We cloned 10 virus-specific TCRs targeting 5 different viruses, causing chronic and acute infection. All 10 TCR genetic constructs were optimized for expression using a P2A sequence, codon optimization and the addition of a non-native disulfide bond. However, maximum TCR expression was only achieved after establishing the optimal orientation of the alpha and beta chains in the expression cassette; 9/10 TCRs favored the beta-P2A-alpha orientation over alpha-P2A-beta. Optimal TCR expression was associated with a significant increase in the frequency of IFN-gamma+ T cells. In addition, activating cells for transduction in the presence of Toll-like receptor ligands further enhanced IFN-gamma production. Thus, we have built a virus-specific TCR library that has potential for therapeutic intervention in chronic viral infection or virus-related cancers.