VACCINIA VIRUS-REPLICATION IS INDEPENDENT OF CELLULAR HSP72 EXPRESSION WHICH IS INDUCED DURING VIRUS-INFECTION

HSP72 is dramatically induced in the ovaries of vaccinia virus (VV)-in fected mice and associates with VV proteins. In order to investigate t he role of HSP72 during vaccinia virus replication, we have constructe d a recombinant vaccinia virus encoding the major inducible cellular H SP72 (VV-HSP72+) and examined the replication characteristics of this virus. VV-HSP72+ exhibited growth kinetics identical to and peak titer s very similar to those of control viruses, both in vitro and in vivo. In particular, replication of VV-HSP72+ was identical to that of cont rol viruses in the HSP72-negative cell line Y3.Ag.1.2.3, and overexpre ssion of HSP72 had no effect on the virulence of VV infection in norma l or immunocompromised mice. We conclude that while VV infection resul ts in the induction of the major inducible 72-kDa HSP, VV replication proceeds normally in the absence of this protein. It is unclear whethe r another celluar chaperone is required to facilitate virus replicatio n in place of HSP72 in Y3.Ag.1.2.3 cells or whether HSP expression pla ys no role in virus replication, but is simply a component of the gene ralized stress response to virus infection. (C) 1996 Academic Press, I nc.