THE PROCESSING, TRANSPORT AND HETEROLOGOUS EXPRESSION OF EPSTEIN-BARR-VIRUS GP-110

Epstein-Barr virus (EBV) glycoprotein gp110 has substantial structural and sequence homology with herpes simplex virus (HSV) gB and gBs of o ther alpha-and betaherpesviruses but unlike HSV gB localizes different ly in infected cells and is absent from virions, To facilitate the ana lysis of EBV gp110, antisera were raised to fragments of gp110 express ed in a bacterial system, They recognized a protein of the predicted s ize in recombinant bacterial lysates, in lymphoblastoid cells and in r ecombinant vaccinia virus-gp110 infected cells, gp110 from all sources possessed a high-mannose type of N-glycosylation implying that gp110 has not passed through the Golgi, Immunofluorescence and immune-electr on microscopy confirmed this conclusion and demonstrated that, in cont rast to HSV gB, the majority of immunoreactive gp110 was present at th e nuclear membrane or endoplasmic reticulum (ER) but not at the cell m embrane, Unexpectedly, a truncated version of gp110 lacking the hydrop hobic C-terminal region, despite forming dimers analogous to HSV dimer s, was transported in a similar manner to full-length gp110, Two chime ric proteins constructed by replacing the Nand C-terminal domains of g p110 with corresponding regions of gp340/220 were also transported to the nuclear membrane/ER, These data suggest that unlike HSV gB both th e N- and C-terminal portions of EBV gp110 contain independent signals sufficient to direct the molecule to the ER/nuclear membrane, Specific transport of gammaherpesvirus gB homologues to the nuclear membrane, from where herpesviruses bud, suggests that they may be involved in th e egress of virus from the nucleus.