MGMT and glioblastoma: Eleven HCMV-GBM strains were isolated from MGMT promoter methylated (n = 4) and MGMT promoter unmethylated (n = 7) GBM tumors by tissue disruption and filtration, and were subsequently grown in MRC5 cells showing a peak of viral load (1–3 log) around day 20 post-infection (Fig. 6a and Supplementary Table 4).