Subretinal delivery of adeno-associated virus serotype 2 results in minimal immune responses that allow repeat vector administration in immunocompetent mice
Article first published online: 1 APR 2009
Copyright © 2009 John Wiley & Sons, Ltd.
The Journal of Gene Medicine
Volume 11, Issue 6, pages 486–497, June 2009
How to Cite
Barker, S. E., Broderick, C. A., Robbie, S. J., Duran, Y., Natkunarajah, M., Buch, P., Balaggan, K. S., MacLaren, R. E., Bainbridge, J. W. B., Smith, A. J. and Ali, R. R. (2009), Subretinal delivery of adeno-associated virus serotype 2 results in minimal immune responses that allow repeat vector administration in immunocompetent mice. J. Gene Med., 11: 486–497. doi: 10.1002/jgm.1327
- Issue published online: 20 MAY 2009
- Article first published online: 1 APR 2009
- Manuscript Accepted: 24 FEB 2009
- Manuscript Revised: 29 JAN 2009
- Manuscript Received: 27 JUN 2008
- UK Department of Health, Moorfields Eye Hospital Special Trustees
- Department of Health's National Institute for Health Research Biomedical Research Centre at Moorfields Eye Hospital
- UCL Institute for Ophthalmology
- immune response;
Adeno-associated virus serotype 2 (AAV2) vectors show considerable promise for ocular gene transfer. However, one potential barrier to efficacious long-term therapy is the development of immune responses against the vector or transgene product.
We evaluated cellular and humoural responses in mice following both single and repeated subretinal administration of AAV2, and examined their effects on RPE65 and green fluorescent protein transgene expression.
Following subretinal administration of vector, splenocytes and T-cells from draining lymph nodes showed minimal activation following stimulation by co-culture with AAV2. Neutralizing antibodies (NAbs) were not detected in the ocular fluids of any mice receiving AAV2 or in the serum of mice receiving a lower dose. NAbs were present in the serum of a proportion of mice receiving a higher dose of the vector. Furthermore, no differences in immunoglobulin titre in serum or ocular fluids against RPE65 protein or AAV2 capsid between treated and control mice were detected. Histological examination showed no evidence of retinal toxicity or leukocyte infiltration compared to uninjected eyes. Repeat administration of low-dose AAV.hRPE65.hRPE65 to both eyes of RPE65−/− mice resulted in transgene expression and functional rescue, but re-administration of high-dose AAV2 resulted in boosted NAb titres and variable transgene expression in the second injected eye.
These data, which were obtained in mice, suggest that, following subretinal injection, immune responses to AAV2 are dose-dependent. Low-dose AAV2 is well tolerated in the eye, with minimal immune responses, and transgene expression after repeat administration of vector is achievable. Higher doses lead to the expression of NAbs that reduce the efficacy of repeated vector administration. Copyright © 2009 John Wiley & Sons, Ltd.