1. ¹Department of Gene Therapy, NHLI, Imperial College, Edinburgh, London, UK
2. ²UK Cystic Fibrosis Gene Therapy Consortium, London, UK
3. ³Lung Immunology Group, Department of Biological Sciences/NHLI, Imperial College, London, UK
4. ⁴DNAVEC Research Inc., Tsukuba, Ibaraki, Japan
5. ⁵Human Disease Immunogenetics Group, Department of Infectious Diseases, Imperial College, London, UK

Correspondence: Dr U Griesenbach, Department of Gene Therapy, ICSM at National Heart & Lung Institute, Faculty of Medicine Imperial College, Manresa Road, London SW3 6LR, UK. E-mail: u.griesenbach@imperial.ac.uk

⁶These authors contributed equally to this work.

Received 14 July 2005; Revised 29 September 2005; Accepted 1 October 2005; Published online 1 December 2005.

Abstract

Sendai virus (SeV) is able to transfect airway epithelial cells efficiently in vivo. However, as with other viral vectors, repeated administration leads to reduced gene expression. We have investigated the impact of inducing immunological tolerance to immunodominant T-cell epitopes on gene expression following repeated administration. Immunodominant CD4 and CD8 T-cell peptide epitopes of SeV were administered to C57BL/6 mice intranasally 10 days before the first virus administration with transmission-incompetent F-protein-deleted F/SeV-GFP. At 21 days after the first virus administration, mice were again transfected with F/SeV. To avoid interference of anti-GFP antibodies, the second transfection was carried out with F/SeV-lacZ. At 2 days after the final transfection lung -galactosidase expression, T-cell proliferation and antibody responses were measured. A state of 'split tolerance' was achieved with reduced T-cell proliferation, but no impact on antiviral antibody production. There was no enhancement of expression on repeat administration; instead, T-cell tolerance was, paradoxically, associated with a more profound extinction of viral expression. Multiple immune mechanisms operate to eradicate viruses from the lung, and these findings indicate that impeding the adaptive T-cell response to the immunodominant viral epitope is not sufficient to prevent the process.