CYTOLYTIC ACTIVITY AND ASSOCIATED SERINE-PROTEASE EXPRESSION BY SKIN AND AFFERENT LYMPH CD8-CELLS DURING ORF VIRUS REINFECTION( T)

Following orf virus reinfection in sheep, CD8(+) T cells were recruite d to the lesion site in the skin during the period of viral replicatio n and appeared in increased numbers in afferent lymph draining the inf ection site. A proportion of the CD8(+) T cells were activated, partic ularly in the skin, as determined by their expression of the cytolytic cell-associated serine protease, BLT-esterase. This was a useful mark er for activated cytolytic cells as there was a good correlation betwe en afferent lymph CD8(+) T cell-mediated lysis of autologous orf virus -infected skin cells and their expression of BLT-esterase in vitro. Th e majority of the cells that expressed BLT-esterase in the skin and ly mph were CD8(+) T cells and cytolysis in vitro was predominately by th e MHC class I antigen presentation pathway. The conclusion is that orf virus reinfection is characterized by limited viral replication and s timulation of an activated CTL response cells as there was a good corr elation between afferent in the skin.