THE ROLE OF THE MAJOR TEGUMENT PROTEIN VP8 OF BOVINE HERPESVIRUS-1 ININFECTION AND IMMUNITY

The tegument of bovine herpesvirus-l (BHV-1) carries an abundant prote in of 96 kDa, termed VP8. Immunolabeling using VP8-specific antiserum and colloidal gold-labeled protein A as the electron-dense marker was used to identify VP8 in the virions and virus-infected cells. VP8 was confirmed to be a tegument protein that, like the herpes simplex virus -1 homologue VP13/14, contains O-linked carbohydrates. VP8 was found i n the nucleus of virus-infected cells as early as 2 hr postinfection. Since VP8 is a gamma2 protein, this protein cannot be newly synthesize d at this rime and must be acquired from the inoculum. This supports t he hypothesis that early during infection, VP8 has a function in modul ation of alpha gene expression. Later during infection, VP8 was observ ed in the cytoplasm around nucleocapsids and in dense inclusions, whic h accumulated in the cisternae of the Golgi. In addition, de novo-synt hesized VP8 continued to accumulate in the nucleus in dense areas and around nucleocapsids. In calves, VP8 stimulated T cell proliferation a nd antibody production, both after BHV-1 challenge and after immunizat ion with purified VP8. These results suggest a role for VP8 in the ind uction of humoral and specifically cell-mediated immunity to BHV-1. (C ) 1995 Academic Press, Inc.