Generation of Norovirus-Specific T-Cells from Human Donors with Extensive Cross-Reactivity to Variant Sequences: Implications for Immunotherapy.

BACKGROUND Chronic norovirus infection in immunocompromised patients can be severe, and presently there is no effective treatment. Adoptive transfer of virus-specific T-cells has proven to be safe and effective for the treatment of many viral infections, and could represent a novel treatment approach for chronic norovirus infection. Hence, we sought to generate human norovirus-specific T-cells (NSTs) that can recognize different viral sequences. METHODS NSTs were generated from peripheral blood of healthy donors by stimulation with overlapping peptide libraries spanning the entire coding sequence of the norovirus genome. RESULTS We successfully generated T-cells targeting multiple norovirus antigens with a mean 4.2 ± 0.5-fold expansion after 10 days. NSTs were comprised of both CD4+ and CD8+ T-cells that expressed markers for central memory and effector memory phenotype with minimal expression of co-inhibitory molecules, and were polyfunctional based on cytokine production. We identified novel CD4 and CD8-restricted immunodominant epitopes within NS6 and VP1 antigens. Furthermore, NSTs showed a high degree of cross-reactivity to multiple variant epitopes from clinical isolates. CONCLUSIONS Our findings identify immunodominant human norovirus T-cell epitopes and demonstrate that it is feasible to generate potent NSTs from third party donors for use in antiviral immunotherapy.