TRANSINHIBITION OF HERPES-SIMPLEX VIRUS-REPLICATION BY AN INDUCIBLE CELL-RESIDENT GENE ENCODING A DYSFUNCTIONAL VP19C CAPSID PROTEIN

This study demonstrates that cells expressing a dysfunctional analog o f a herpes simplex virus (HSV) capsid protein inhibits HSV replication . Vero cell lines expressing HSV-1 capsid protein VP19c/beta-galactosi dase fusion proteins were constructed and tested for their kinetics of expression, intracellular location, and ability to interfere with HSV replication. Two chimeric genes were constructed for these studies. T he larger chimeric gene encodes the amino terminal 327 amino acids (aa ) of VP19c fused to the carboxy terminal 1026 aa of beta-galactosidase , and the shorter chimeric gene encodes VP19c aa 1-30 and 302-327 fuse d to the carboxy-terminal 1026 aa of beta-galactosidase. Cell lines V3 2G-1 and V32G-2 containing the larger and the shorter chimeric genes, respectively, were isolated after cotransfection with plasmid pSV2-neo DNA, cell selection, and limiting-dilution cloning. The chimeric VP19 c/beta-galactosidase genes resident in V32G-1 and V32G-2 cell lines we re induced by early gene products of superinfecting wild-type HSV-1 an d HSV-2, but were not constitutively expressed. The hybrid proteins ex pressed in infected V32G-1 and V32G-2 cells both colocalized with infe cted cell protein 8 (ICP8) into virus-replicative compartments in the cell nuclei. HSV-1 and HSV-2 growth in V32G-1 cells (which express the larger chimeric gene) was significantly reduced compared to growth in V32G-2 and control Vero cells. The data suggest that the larger VP19c /beta-galactosidase hybrid protein interferes with virus capsid assemb ly or morphogenesis in a competitive manner. Results also demonstrate that a small portion of VP19c containing the predicted endoplasmic ret iculum signal sequence for this capsid protein (aa 1-30) promotes inco rporation of the VP19c/beta-galactosidase fusion proteins into nuclear viral replication compartments.