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ML Caro, DM Estes, LA Cohn, K Narfström; The Systemic and Ocular Immune Response After Recombinant Adeno-Associated Virus Gene Transfer of RPE65 in 6 Dogs Affected With the RPE65 Null Mutation . Invest. Ophthalmol. Vis. Sci. 2002;43(13):4594.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To evaluate potential systemic and local adverse effects after recombinant Adeno-Associated Virus (rAAV) gene transfer of Retinal Pigmented Epithelium 65 (RPE65) into the subretinal space of dogs affected with the RPE65 null mutation. Methods: Blood samples were collected weekly for three weeks before treatment to establish base line and subsequently one week after treatment and monthly thereafter in six dogs aged 4 (3 dogs), 8 (2 dogs) and 11 months (1dog). Serum chemistry profiles (SCP), complete blood cell counts (CBC), lymphocyte blastogenesis (LBT) and anti- viral antibody test in response to canine adenovirus-1 and canine parvovirus vaccination, were performed in order to determine immune competence. Complete urine analyses (UA) and urine protein and creatinine ratio (UP: UC) were performed. Serum was subjected to Western blot analyses for the presence of escape RPE65 and rAAV. Vitreous and aqueous humor from one 8-mo-old dog were tested by Western blot for the presence of the rAAV and transcription of the RPE65. Results: Two dogs (4 and 8 mo) developed uveitis 21 and 5 days, respectively, after treatment and were treated symptomatically with prednisolone (1-2 mg/kg). The uveitis of the 1st dog subsided after one week of systemic and topical treatment while the 2nd dog was euthanized 3 months after therapy due to systemic complications after long-term steroid treatment that resulted in iatrogenic hyperadrenocortisism. SCP, CBC, and UA and UP: UC were initially within the reference range in this dog but abnormalities consistent with iatrogenic hyperadrenocortisism were eventually observed. A mild lymphopenia one-month post therapy in all 6 animals was noticed, which normalized a month later. All dogs demonstrated immune competency by showing adequate anti-viral antibody titers to previous vaccinations. The LBT test indicated normal T and B cells function. No escape of rAAV or RPE65 was detected by Western blot. No systemic or ocular adverse effects to the rAAV. RPE65 gene transfer was observed in any of the other treated dogs. Conclusion: It appears that there is no escape of rAAV and RPE65 after gene transfer to the subretinal space and that there are no adverse systemic effects as monitored by routine clinical testing. There is, however, a risk for uveitis to develop due to subretinal injection of the rAAV. RPE65, most likely a local immune reaction.
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