CYTOTOXIC T-LYMPHOCYTE RESPONSES IN CATTLE INFECTED WITH BOVINE VIRALDIARRHEA VIRUS

A system for a reproducible in vitro restimulation of bovine viral dia rrhea virus (BVDV)-specific cytotoxic T-cells (CTL) was developed. Lym phocyte cultures of BVDV-immunised cattle were stimulated with infecti ous BVDV isolate PT810 and recombinant bovine interleukin-2 for 12 to 25 days. A specific lysis of Concanavalin A-stimulated BVDV-infected a utologous target cells was observed, whereas allogeneic BVDV-infected target cells were only marginally lysed as detected by flow cytometry. BVDV-specific lymphocyte transformation was further characterised by the expression of bovine lymphocyte activation antigens and bovine MHC class-ii molecules. Secondary stimulation of CTL was influenced by in vitro production of BVDV-specific neutralising antibodies, which were secreted exclusively in BVDV-inoculated lymphocyte cultures of immuni sed cattle. These results demonstrate the presence of CTL in periphera l blood mononuclear cells (PBMC) of immunised cattle which can kill au tologous BVDV-infected antigen-presenting cells after in vitro restimu lation. (C) 1997 Elsevier Science B.V.