Identification of Different Target Glycoproteins for Bovine Herpes Virus Type 1-Specific Cytotoxic T Lymphocytes Depending on the Method of in Vitro Stimulation

Vaccinia virus recombinants expressing the three major bovine herpes virus-1 (BHV-1) glycoproteins gI, gIII and gIV were used to identify the major target antigens for BHV-1-specific CTL isolated from immune cattle. Peripheral blood mononuclear cells (PBMC) expanded in vitro in the presence of interleukin-2 (IL-2) and lysed both gIII- and gIV-infected target cells. Secondary in vitro stimulation of PBMC was also performed in the presence of either fixed BHV-1-infected autologous fibroblasts or ultraviolet (UV)-inactivated virus. Both methods of antigen presentation allowed the proliferation of BHV-1-specific CTL but the target glycoprotein for these CTL differed depending on the method of stimulation. Vaccinia-gIV-infected targets were lysed predominantly when PBMC were stimulated by fixed infected fibroblasts, whilst PBMC stimulated by UV-inactivated virus lysed mostly vaccinia-gIII-infected targets. This observation could be explained by a different processing pathway of BHV-1 antigens in each cell type involved.