Expression of cytotoxicity-associated genes in Marek's disease virus-infected chickens.

Cytotoxic host responses to Marek's disease virus (MDV) have been attributed to both natural killer (NK) cells and cytotoxic T lymphocytes (CTLs). However, the mechanisms of cell lysis initiated by these cytotoxic responses during MDV infection are not well defined. Therefore, the current study was aimed at elucidating the molecular mechanisms of host cytotoxic responses to MDV infection by investigating the expression of genes in the cell lysis pathway involving granzyme A. Genes encoding cytolytic proteins, NK lysin, and granzyme A were upregulated during early stages of infection, whereas the genes encoding major histocompatibility complex (MHC) class I and the DNA repair and apoptosis protein, poly(ADP-ribose) polymerase (PARP), were downregulated. These findings shed more light on the mechanisms of host response to MDV infection in chickens.