Fig. 6

The oncolytic efficacy of PRV-LAV depends on CD8⁺ T cells in a CT26 mouse model. A-G Tumor immune infiltrates were analyzed by flow cytometry on the day after mice received the final of 4 doses of vehicle (n = 8) or PRV-LAV (n = 8) treatment. The numbers of tumor-infiltrating CD4⁺ T cells, CD8⁺ T cells, dendritic cells, macrophages, monocytes, and neutrophils per gram tumor were calculated (A). The mean fluorescence intensities of CD80 and CD86 on dendritic cells (B) and macrophages (C) were determined, as was the mean fluorescence intensity of CD80 on monocytes (D) and neutrophils (E). The mean fluorescence intensities of CTLA4, PD-1, and TIM3 on CD4⁺ T cells (F) and CD8⁺ T cells (G) were determined. Data are presented as the mean ± s.d. values. The black bars indicate the mean values. A t test was used to determine the significance of differences. *P < 0.05; **P < 0.01; ***P < 0.001; ****P < 0.0001. H-J Knockout of CD4⁺ and CD8⁺ T cells during PRV-LAV treatment. Changes in the tumor volume curves (H) and Kaplan–Meier survival curves (I) for mice bearing CT26 tumors treated with PRV-LAV (1 × 10.⁷ PFUs, intratumorally). Changes in the tumor volume curves for each mouse are shown in (J). Changes in the tumor volumes are expressed as the mean ± SEM values (n = 6). In (H), statistical analysis was performed by repeated measure ANOVA. Statistical analysis was performed using the log-rank test in (I). *P < 0.05; **P < 0.01; ***P < 0.001; ****P < 0.0001