HSF1 overexpression enhances the oncolytic effect of Adel55 in nude mice tumor model by increasing Adel55 spreading and tumor apoptosis. (A) Detection of HSF1 expression, Adel55 spreading or apoptotic rates in tumors. 30 days after injection, cHSF1 and Adel55 hexon expression in each treated group was detected by immunostaining with anti-HSF1 or anti-hexon antibody, respectively. Apoptotic rate in each group was detected by an in situ cell apoptosis detection kit. (B) The apoptotic index of the mean values of sections from three mice in each group and are presented as means ± SD (n = 3; *P < 0.05, Bcap37/HSF1i vs Bcap37 or Bcap37/LXSN; **P < 0.01, Bcap37/cHSF1 vs other groups). (C) The replication of Adel55 in vivo. The Adel55 virus progeny recovered from the xenografts was titrated for virus production by standard plaque assay on 293 cells. The titer was adjusted to the weight of each tumor and expressed as PFU/g tissue. Each column represents the mean titer ± SD (n = 3).