Characterization of Marek's disease herpesvirus-specific cytotoxic T lymphocytes in chickens inoculated with a non-oncogenic vaccine strain of MDV

Previously we have reported that reticuloendotheliosis virus (REV)-transformed cell lines expressing Marek's disease virus (MDV) genes pp38, meg or gB were lysed by syngeneic MDV-specific splenocytes from major histocompatibility complex (MHC):(BB19)-B-9 and MHC:(BB21)-B-1 chickens. In contrast, REV-transformed cell lines expressing the MDV gene ICP4 were only lysed by syngeneic MDV-specific splenocytes from MHC:(BB21)-B-21 chickens. In this study we report that this syngeneic cell-mediated immune response is induced by cytotoxic T lymphocytes (CTL). Splenocytes from MDV vaccine strain, SB-1 inoculated MHC:(BB19)-B-19 and MHC:(BB21)-B-21 chickens, depleted for CD4(+), CD8(+), TCR gamma delta(+), TCR alpha beta 1(+) and/or TCR alpha beta 2(+) cells, were used as effector cells in chromium-release assays. Effector cells depleted of CD8(+) or TCR alpha beta 1,(+) but not TCR gamma delta(+) or TCR alpha beta 2(+), markedly reduced the MDV-specific release. Depletion of CD4(+) effector cells did not influence the specific release significantly. This is the first report on identification of virus-specific CD8(+) CTL in chickens inoculated with a non-oncogenic vaccine strain of MDV.