Infection of chicken cells with three Marek's disease virus (MDV) serotypes interferes with expression of the major histocompatibility complex (MHC or B complex) class I (BF) glycoproteins. BF surface expression is blocked after infection of OU2 cells with MDV serotypes 1, 2, and 3. MDV-induced T-cell tumors suffer a nearly complete loss of cell surface BF upon virus reactivation with 5-bromo-2'-deoxyuridine (BUdR). The recombinant virus (RB1BUS2gfpDelta) transforming the MDCC-UA04 cell line expresses green fluorescent protein (GFP) during the immediate early phase of viral gene expression. Of the UA04 cells induced to express the immediate early GFP, approximately 60% have reduced levels of BF expression. All of the reactivated UA04 and MSB1 tumor cells expressing the major early viral protein pp38 display reduced levels of BF. Thus, BF down-regulation begins in the immediate early phase and is complete by the early phase of viral gene expression. The intracellular pool of BF is not appreciably affected, indicating that the likely mechanism is a block in BF transport and not the result of transcriptional or translational regulation.
Copyright 2001 Academic Press.