MUTANT HERPES SIMPLEX VIRUS-MEDIATED SUPPRESSION OF RETINOBLASTOMA

Purpose. To test the ability of a mutant herpes simplex virus (HSV) hrR3 to inhibit growth of Y79 human retinoblastoma in vitro and in vivo. Methods. Cultured Y79 cells were infected with multiplicities of infection (MOI) ranging from 0.004 to 0.1 of hrR3. Surviving cells were counted using trypan blue dye exclusion. Using X-gal staining, expression of the lacZ gene was examined in vitro on day 3 postinfection to evaluate viral replication. Nude mice harboring Y79 tumors subcutaneously received an intraneoplasmic injection of 5 × 10 7 plaque-forming units of hrR3. The tumor sizes were measured weekly. Expression of the lacZ gene was also examined on one week postinfection. Results. There are 31% and 13% cells surviving in cultured Y79 cells infected by hrR3 at an MOI of 0.1 on days 3 and 5 postinfection respectively compared to those of mock-infected cells. Also more than 70% of Y79 cells were stained with X-gal at an MOI of 0.1 which demonstrated active viral replication in vitro. Virus-treated subcutane...