Selective effects of E1B-defective adenoviruses and adenovirus E1A mutantsin deficient mouse primary embryonic fibroblasts

E1B-defective adenoviruses have been described as exerting selective cytopa thic effects on transformed cells. Previously, we showed that adenovirus dl 118, lacking both E1B proteins, very efficiently kills most human malignant cell lines. In order to study whether these selective effects were due to selective replication of dl118 in cells harboring specific genetic alterati ons, we compared the viability of various deficient mouse primary fibroblas ts. We studied mouse embryonic fibroblasts (MEFs) derived from p16, p21, p2 7 and p53 knockout mice, as well as wild-type MEFs. We infected them with 1 00 p.f.u. of adenoviruses adl118, adwt300, and adenoviruses carrying the E1 A mutant 922 (the Ela product only binds to the p300 and related proteins) and Ad646 (the E1A product binds to the pRb and related proteins). The perc entage of infectivity was evaluated with an adenovirus carrying the green f luorescent protein (AdGFP). With AdGFP, clear green fluorescent signals wer e detected in more than 70% of the cells after 3 days of infection. After i nfection with several adenoviruses, we observed that E1A mutant 922 killed all the MFFs. Conversely, the E1a mutant Ad646 exerted its major effects on control wild-type MEFs. Moreover, Adl118 killed the wtMEFs and other MEFs slightly more efficiently than did wtAd, but less than Ad922. No viral repl ication was detected by adding the obtained supernatants to HEK293 cells. D ue to the absence of significant viral replication on these cells, the resu lts could be interpreted as direct effects of E1A and E1A mutant proteins o n the different mouse cells carrying diverse genetic alterations.