PHENOTYPE, GROWTH-REGULATION AND CYTOKINE TRANSCRIPTION IN-OVINE HERPESVIRUS-2 (OHV-2)-INFECTED BOVINE T-CELL LINES

The causal agent of sheep-associated malignant catarrhal fever (MCF), Ovine Herpesvirus-2 (OHV-2), can be propagated in IL-2-dependent lymph oblastoid cell lines derived from diseased cattle and deer providing a useful model for the investigation of the pathogenesis of MCF In this study, five interleukin-2 (IL-2)-dependent cell lines were establishe d from affected cattle to examine their growth regulation and cytokine transcription. All cell lines expressed CD?, CD5 and CD25. Three of t he cell Lines were CD4(+) and one CD8(+), whereas one cell was of mixe d CD4 and CD8 phenotye. The growth of these cell lines was reduced whe n cultured with antibody against CD25, the IL-I receptor alpha subunit . All cell lines showed a lack of response to Con A and their cell gro wth was inhibited by Cyclosporin A which is known to inhibit cytokine promoters. It was decided therefore, to examine the cell lines for the presence of mRNA of different cytokines. The results showed that the cell lines transcribed message for IFN gamma, TNF alpha, IL-4 and IL-1 0 whereas no mRNA for IL-2 or IL-1 beta was detected. In conclusion, t he OHV-2-immortalised cell lines resemble anergic T-cells which may be activated giving rise to the characteristic lesions of MCF. (C) 1998 Elsevier Science B.V. All rights reserved.