POLIOVIRUS REPLICONS THAT EXPRESS THE GAG OR THE ENVELOPE SURFACE PROTEIN OF SIMIAN IMMUNODEFICIENCY VIRUS SIVSMM PBJ14

Poliovirus genomes encoding the complete gag or env surface gene of th e simian immunodeficiency virus SIVsmm PBj14 (SIV-PBj14) were construc ted. The in vitro-transcribed RNA from these genomes, referred to as r eplicons, have the capacity for self-replication when transfected into tissue culture cells. Serial passage of the replicons containing the SIV-PBj14 gag or SIV-PBj14 env (SU) genes with a recombinant vaccinia virus, VV-P1, which provides P1 in trans, resulted in the encapsidatio n of these replicons. Infection of cells with the encapsidated replico ns that encode gag, referred to as vlC-SIV-PBj14 Gag, resulted in the production of a 55-kDa protein that was released from the infected cel ls. Using a sucrose density-gradient analysis, the protein was found t o sediment at a density consistent with that of a virus-like particle. Infection of cells with a replicon that encodes the env SU gene, refe rred to as vlC-SIV-PBj14 SU, resulted in the production of two SIV-PBj 14 envelope-related intracellular proteins. One of these proteins had a molecular mass consistent with that of the unglycosylated SIV-PBj14 SU protein (63 kDa); the second protein had a higher molecular mass (> 160 kDa). Characterization of this larger protein revealed that it was glycosylated and possibly represented a dimer of the SU protein. A pu lse-chase analysis of cells infected with vlC-SIV-PBj14 SU demonstrate d that a 110- to 130-kDa protein was released, which is consistent wit h the molecular mass of the SIV-PBj14 SU protein. The results of these studies demonstrate that poliovirus replicons can be used to express foreign proteins, including glycoproteins, which retain many of the ph ysical features of the native protein. (C) 1996 Academic Press, Inc.