Herpes simplex virus mediated gene transfer to primate ocular tissues

We evaluated the feasibility of delivering a gene into monkey eyes using a replication-competent herpes simplex virus (HSV) type 1 ribonucleotide reductase mutant (hrR3) expressing the Escherichia coli lacZ gene. To determine the efficiency of in vitro HSV-mediated gene transfer, cultured human trabecular meshwork (HTM) and human ciliary muscle (HCM) cells were infected with hrR3 and beta-galactosidase activity was measured histochemically. Six cynomolgus monkey eyes received viral injections into the anterior chamber (2 x 10(7) pfu) and/or the vitreous (5 x 107 pfu), and the distribution of cells expressing lacZ was evaluated. In vitro, both cultured HTM and HCM cells displayed multiplicity-dependent beta-galactosidase activity. In vivo, intracameral and/or intravitreal injection resulted in transgene expression in TM cells and in non-pigmented ciliary epithelial cells (NPE), but not in CM cells. Transgene expression was also detected in retinal pigmented epithelial (RPE) cells and sporadic retinal ganglion cells (RGC) in eyes receiving virus intracamerally and intravitreally respectively. We observed significant inflammation in the anterior chamber, TM and CM in virus-injected eyes, along with mild vitritis and retinitis. This study demonstrates successful gene transfer using hrR3 as a vector in human ocular cells and in ocular tissues in living monkeys. Further investigation of the etiology of the inflammatory response, possible cytotoxicity, and limited duration of transgene expression is necessary in order to make this technique clinically applicable. (C) 1999 Academic Press.