VACCINATION WITH THE IMMEDIATE-EARLY PROTEIN ICP47 OF HERPES-SIMPLEX VIRUS-TYPE-1 (HSV-1) INDUCES VIRUS-SPECIFIC LYMPHOPROLIFERATION, BUT FAILS TO PROTECT AGAINST LETHAL CHALLENGE

Assessing the immunobiological function of the individual proteins of herpes simplex virus-type 1 (HSV-1) continues to be important in eluci dating virus-host interactions and for the rational design of subunit vaccines. In this report, the non-structural, immediate-early protein ICP47 of HSV-1 was examined for its ability to induce virus-specific i mmune responses. The ICP47 protein, when expressed from a recombinant vaccinia virus or when produced by cell-free, in vitro translation, in duced a vigorous HSV-1-specific lymphoproliferative response. However, other common parameters of immunity such as neutralizing antibody, de layed-type hypersensitivity, and class I major histocompatibility comp lex (MHC)-restricted cytotoxic T lymphocytes (CTL) were not induced by ICP47. Moreover, mice immunized with vaccinia-expressed ICP47 were un able to survive lethal challenge with virulent HSV, indicating that in spite of its ability to induce significant HSV-1-specific lymphoproli feration, ICP47 appears unable to afford protective immunity in vivo. Possible reasons for this failure and the implications of these result s in terms of vaccine design are discussed. (C) 1994 Academic Press, I nc.