MULTIPLE MECHANISMS FOR THE INHIBITION OF ENTRY AND UNCOATING OF SUPERINFECTING SEMLIKI-FOREST-VIRUS

Recombinant Semliki Forest viruses (SFV) that express one or none of t he viral structural proteins were used to infect cells and to analyze the fate of incoming superinfecting wild-type viruses. It was found th at in addition to the previously described block in replication that s uperinfecting viruses encounter within 15 min of infection, other mech anisms of superinfection inhibition occurred al later times. Over a 6- hr infection period, inhibition was seen in binding of virus to the ce ll surface, in acid-activated penetration into the cytoplasm, and in u ncoating of nucleocapsids. For each of these processes, the inhibitory mechanism was investigated. In summary, we found that infection evoke d several independent mechanisms for blocking the entry and uncoating of superinfecting viruses. The results also offered new insights into the normal processes of penetration and uncoating of SFV. (C) 1997 Aca demic Press.