Additional transduction events after subretinal readministration of recombinant adeno-associated virus

Subretinal delivery of recombinant adeno-associated virus (rAAV) results in a systemic humoral response in the adult immunocompetent mouse. We charact erized this response end determined whether it is possible to readminister rAAV to the subretinal space despite the presence of antibodies to the vect or, A systemic humoral response to rAAV capsid proteins was induced by eith er unilateral subretinal injection or by intradermal administration of 1 x 10(9) infectious units of rAAV carrying the cDNA encoding green fluorescent protein (GFP), rAAV-GFP, Experiments were performed in cohorts of adult C5 7BL/6 mice, Assessment of systemic humoral response to viral capsid protein :was performed through enzyme-linked immunoabsorbent assay (ELISA) and infe ction inhibition studies of serum samples 3 weeks after virus delivery, The rAAV-GFP virus was readministered by subretinal injection, GFP expression after subretinal administration was evaluated ophthalmoscopically throughou t the course of: the experiment and histologically at the termination of th e experiment. We observed significant systemic humoral responses to viral c apsid protein after subretinal delivery of rAAV. Intradermal injection resu lted in a-larger humoral response (with a higher percentage of neutralizing antibodies) than subretinal injection. Additional transduction events were observed after readministration of rAAV despite the presence of strong hum oral response to the vector.