Purpose: The ability of replication-deficient adenovirus to mediate gene transfer to retinal cells was evaluated.
Methods: A replication-deficient adenoviral vector, AdCMV beta A.ntlacZ, which contains the bacterial beta-galactosidase (lacZ) reporter gene, was injected into the subretinal space of normal, rd, and rds strains of mice at various ages. The efficiency and duration of transgene expression were assessed by histochemical examination and transmission electron microscopy.
Results: AdCMV beta A.ntlacZ was effective in mediating gene transfer to the retinal pigment epithelial cells, rod and cone photoreceptor cells, and cells in the inner nuclear layer of the retina for periods of up to 1 month. Gene transfer to retinal pigment epithelial cells occurred at much lower viral titers than was required for gene transfer to photoreceptor cells. The extent to which photoreceptor cells could be transduced varied with the age of the animals and the conditions of the photoreceptor cells: greater numbers of photoreceptor cells were transduced in 5- to 7-day-old pups and in mice at the initial stages of photoreceptor degeneration than in normal adult mice. No evidence of gross pathogenic effects or viremia in recipient mice was observed.
Conclusions: Replication-deficient adenovirus mediates transfer and expression of a foreign gene in retinal pigment epithelial and photoreceptor cells. Gene transfer to photoreceptor cells is enhanced in developing retinas or at the predegenerate stage of photoreceptors in genetically programmed retinal degeneration.