Figure 2. Systemic delivery of viral strains to tumors.

1 × 10⁹ PFU of vaccinia strain WR or Ad5 were delivered i.v. to immuno­competent mice bearing subcutaneous CMT 64 or JC tumors (both lines susceptible to replication by both viruses after intratumoral injection). Mice were sacrificed after 48 or 72 hours or after 10 days and immunohistochemistry performed against viral coat proteins on paraffin-embedded sections of tumor tissue. (A) Graphs show scoring of positive cells in each tumor (asterisk indicates none detectable). For each condition, results are based on tumors from 3 mice, and for each tumor, 10 randomly chosen fields of view were scored. (B) Representative photographs show sections at 72 hours and 10 days after treatment (original magnification, ×100).