Marek's disease virus down-regulates surface expression of MHC (B complex)class 1 (BF) glycoproteins during active but not latent infection of chicken cells

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 af ter infection of OU2 cells with MDV serotypes 1, 2, and 3. MDV-induced T-ce ll tumors suffer a nearly complete loss of cell surface BF upon virus react ivation with 5-bromo-2'-deoxyuridine (BUdR). The recombinant virus (RB1BUS2 gfp Delta) transforming the MDCC-UA04 cell line expresses green fluorescent protein (GFP) during the immediate early phase of viral gene expression. O f the UA04 cells induced to express the immediate early GFP, approximately 60% have reduced levels of BF expression. All of the reactivated UA04 and M SB1 tumor cells expressing the major early viral protein pp38 display reduc ed revels of BF. Thus, BF down-regulation begins in the immediate early pha se and is complete by the early phase of viral gene expression. The intrace llular pool of BF is not appreciably affected, indicating that the likely m echanism is a block in BF transport and not the result of transcriptional o r translational regulation. (C) 2001 Academic Press.