VZV GLYCOPROTEIN I IS IMPORTANT BUT NOT ESSENTIAL FOR THE TRAFFICKING AND SURFACE EXPRESSION OF GLYCOPROTEIN E

*C. Mo, J. Lee, M.H. Sommer & A.M. Arvin
Department of Pediatrics, Stanford University, Stanford, CA

Varicella zoster virus glycoprotein E (gE) is the most abundant VZV glycoprotein on the surface of virus-infected cells. VZV gE has targeting sequences for the trans-Golgi network (TGN) and is transported from the ER to the TGN in infected and gE-transfected cells. In this study, VZV gE expressing melanoma cell lines were generated. gE is expressed under the control of the reverse Tet repressor (Tet-On). These stably transfected cell lines (Met-gE) can be maintained without potential toxic effects of constitutive gE expression. In contrast to the gE localization pattern in transient transfected cells, gE induced by Tet-On is retained at the ER as well as in the cis-Golgi by immunofluorescence confocal microscopy and immunogold EM analysis. To test whether other viral protein(s) may facilitate gE trafficking and surface localization, MSPgE-vOka virus that contains MSPgE in place of wt gE was made. MAb 3B3 anti-gE antibody does not bind to MSPgE. This MAb was used to track the localization of gE in Met-gE cells post MSPgE-vOka infection. gE became detectable at the TGN and on the cell surface. Several viral proteins are considered to play a role in gE trafficking, such as gI, ORF 47, ORF66 etc. Since gE and gI form heterodimers, MSPgE-vOka virus without gI (MSPgE-vOkagI-) was constructed to assess the role of gI in gE trafficking. In the absence of gI, gE was still detectable at the TGN and on the cell surface. These data indicate that gI is not absolutely required for gE trafficking.

Corresponding Author: Chengjun Mo, Ph.D., VZV Research Foundation Fellow, Department of Pediatrics, Infectious Diseases Division, G312, Stanford University School of Medicine, Stanford, CA 94305, USA