Fig. 3.

Examples of strategies to obtain oncolytic adenoviruses with tumor selective replication (A) or an enhanced tumor tropism (B and C). A) By mutating the E1A or E1B genes the replication is restricted to pRB or p53 deficient cells, respectively. The expression of E1A under tumor specific promoters, like human telomerase promoter (hTERT), allows viral replication only in tumor cells. B) Generation of chimeric Ad5 viruses by fiber replacement from another serotype (AdX), thus obtaining an Ad5 with the tropism of the AdX. C) Addition of the integrin binding motif CDCRGDCDC within the knob domain of the fiber.