Fig. 1.

Tumor infection and intratumoral proliferation and persistence of HSV (LacZ expression). (A and B) Intratumoral distribution of HSV-mediated gene expression is shown by blue stain of infected cells expressing E. coli β-galactosidase. Two magnifications show tumors extracted from control rats (−CPA/+HSV, two upper rows) and from rats treated with CPA 48 h before injection with virus (+CPA/+HSV, two lower rows). Microphotographs show tumors 6 h after viral injection (48 h after CPA treatment), before viral replication (A) and 72 h after viral injection (5 days after CPA treatment), when several rounds of HSV replication should have occurred (B). (C) Quantitative enumeration of the percentage of tumor area infected by HSV at 6 and 72 h after viral injection in control rats and rats pretreated with CPA (three rats per treatment group). Significant differences were observed for the 6-h versus 72-h time points and for control animals versus those treated with CPA at 72 h.