title: Codon optimization of the human papillomavirus E7 oncogene induces a CD8+ T cell response to a cryptic epitope not harbored by wild-type E7.
abstract: Codon optimization of nucleotide sequences is a widely used method to achieve high levels of transgene expression for basic and clinical research. Until now, immunological side effects have not been described. To trigger T cell responses against human papillomavirus, we incubated T cells with dendritic cells that were pulsed with RNA encoding the codon-optimized E7 oncogene. All T cell receptors isolated from responding T cell clones recognized target cells expressing the codon-optimized E7 gene but not the wild type E7 sequence. Epitope mapping revealed recognition of a cryptic epitope from the +3 alternative reading frame of codon-optimized E7, which is not encoded by the wild type E7 sequence. The introduction of a stop codon into the +3 alternative reading frame protected the transgene product from recognition by T cell receptor gene-modified T cells. This is the first experimental study demonstrating that codon optimization can render a transgene artificially immunogenic through generation of a dominant cryptic epitope. This finding may be of great importance for the clinical field of gene therapy to avoid rejection of gene-corrected cells and for the design of DNA- and RNA-based vaccines, where codon optimization may artificially add a strong immunogenic component to the vaccine.
authors: Max-Delbrück-Center for Molecular Medicine, Berlin, Germany.
authors: Felix K M
authors: FK
authors: Lorenz
authors: Institute for Molecular Immunology, Helmholtz-Zentrum München, Munich, Germany.
authors: Susanne
authors: S
authors: Wilde
authors: Max-Delbrück-Center for Molecular Medicine, Berlin, Germany.
authors: Katrin
authors: K
authors: Voigt
authors: Institute of Biology, Humboldt University, Berlin, Germany.
authors: Elisa
authors: E
authors: Kieback
authors: Institute for Molecular Immunology, Helmholtz-Zentrum München, Munich, Germany.
authors: Barbara
authors: B
authors: Mosetter
authors: Institute for Molecular Immunology, Helmholtz-Zentrum München, Munich, Germany.
authors: Dolores J
authors: DJ
authors: Schendel
authors: Max-Delbrück-Center for Molecular Medicine, Berlin, Germany; Institute of Biology, Humboldt University, Berlin, Germany.
authors: Wolfgang
authors: W
authors: Uckert
mesh_terms: D018414:CD8-Positive T-Lymphocytes / Q000502:physiology*; D002478:Cells, Cultured; D003062:Codon; D018604:Epitope Mapping; D015316:Genetic Therapy / Q000379:methods; D006801:Humans; D027383:Papillomaviridae / Q000276:immunology*; D050725:Papillomavirus E7 Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology*
chemical_list: D003062:Codon; D050725:Papillomavirus E7 Proteins