RESUMO
Retinal gene therapy with adeno-associated viral (AAV) vectors is safe and effective in humans. However, the limited cargo capacity of AAV prevents their use for therapy of those inherited retinopathies (IRs) due to mutations in large (>5 kb) genes. Viral vectors derived from adenovirus (Ad), lentivirus (LV) and herpes virus (HV) can package large DNA sequences, but do not target efficiently retinal photoreceptors (PRs) where the majority of genes responsible for IRs are expressed. Here, we have evaluated the mouse retinal transduction profiles of vectors derived from 16 different Ad serotypes, 7 LV pseudotypes and from a bovine HV. Most of the vectors tested transduced efficiently the retinal pigment epithelium. We found that LV-GP64 tends to transduce more PRs than the canonical LV-VSVG, albeit this was restricted to a narrow region. We observed more extensive PR transduction with HdAd1, 2 and 5/F35++ than with LV, although none of them outperformed the canonical HdAd5 or matched the extension of PR transduction achieved with AAV2/8.
Assuntos
Dependovirus/genética , Herpesvirus Bovino 4/genética , Lentivirus/genética , Epitélio Pigmentado da Retina/virologia , Animais , Dependovirus/classificação , Eletrorretinografia , Células Epiteliais/virologia , Vetores Genéticos/administração & dosagem , Proteínas de Fluorescência Verde/genética , Proteínas de Fluorescência Verde/metabolismo , Herpesvirus Bovino 4/classificação , Lentivirus/classificação , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Células Fotorreceptoras de Vertebrados/metabolismo , Epitélio Pigmentado da Retina/citologia , Transdução GenéticaRESUMO
Gene therapy with adeno-associated viral (AAV) vectors is limited by AAV cargo capacity that prevents their application to the inherited retinal diseases (IRDs), such as Stargardt disease (STGD) or Usher syndrome type IB (USH1B), which are due to mutations in genes larger than 5 kb. Trans-splicing or hybrid dual AAV vectors have been successfully exploited to reconstitute large gene expression in the mouse retina. Here, we tested them in the large cone-enriched pig retina that closely mimics the human retina. We found that dual AAV trans-splicing and hybrid vectors transduce pig photoreceptors, the major cell targets for treatment of IRDs, to levels that were about two- to threefold lower than those obtained with a single AAV vector of normal size. This efficiency is significantly higher than that in mice, and is potentially due to the high levels of dual AAV co-transduction we observe in pigs. We also show that subretinal delivery in pigs of dual AAV trans-splicing and hybrid vectors successfully reconstitute, albeit at variable levels, the expression of the large genes ABCA4 and MYO7A mutated in STGD and USH1B, respectively. Our data support the potential of dual AAV vectors for large gene reconstitution in the cone-enriched pig retina that is a relevant preclinical model.