| The importance of cytotoxic T lymphocytes (CTLs) in the immune responses in chickens infected with Marek's disease virus (MDV) has not been elucidated. This lack of knowledge is caused by a combination of the absence of major histocompatibility complex (MHC)-defined cells that are susceptible to infection with MDV and the inability to infect target cells at a high multiplicity of infection due to the strictly cell-associated nature of MDV. Preliminary studies suggested that syngeneic MDV-sensitized spleen cells can lyse REV-transformed cell lines expressing MDV pp38.; In this study, MDV pp38, meq, ICP4, ICP22, gB, ORF A, A41 or L1 genes were cloned into an eukaryotic expression vector and stably transfected into reticuloendotheliosis-transformed cells expressing MHC: {dollar}Bsp{lcub}19{rcub}Bsp{lcub}19{rcub}{dollar} and MHC: {dollar}Bsp{lcub}21{rcub}Bsp{lcub}21{rcub}.{dollar} Cell lines positive for MDV gene transcription and/or protein expression were used as target cells in chromium release assays (CRA). Effector cells for CRA's were obtained from spleens of chickens infected with the JM16 or SB-1 strains of MDV. Cell lines expressing MDV pp38, meq or gB were lysed by syngeneic but not allogeneic MDV-sensitized spleen cells. Syngeneic CTL against ICP4 were detected only in spleen from MHC: {dollar}Bsp{lcub}21{rcub}Bsp{lcub}21{rcub}{dollar} chickens. Syngeneic CTL responses were not detected against MHC: {dollar}Bsp{lcub}19{rcub}Bsp{lcub}19{rcub}{dollar} and MHC: {dollar}Bsp{lcub}21{rcub}Bsp{lcub}21{rcub}{dollar} cell lines expressing A41, L1, ORF A or ICP22.; These CTLs expressed CD8 and TCR{dollar}alphabeta{dollar}1 but not CD4, TCR{dollar}gammadelta{dollar} or TCR{dollar}alphabeta{dollar}2 antigens. Vaccination with recombinant fowlpox virus expressing MDV gB (rFPV-gB) produced CTLs that lysed gB--but not pp38--expressing target cells. The rFPV-gB-sensitized CTLs also express CD8 and TCR{dollar}alphabeta{dollar}1 but not CD4, TCR{dollar}gammadelta{dollar} or TCR{dollar}alphabeta{dollar}2 antigens. An attempt was made to identify the pp38 and ICP4 sequences that encode for epitopes recognized by CTLs obtained from chickens infected with MDV. |
