Differential Regulation of D(k) and K(k) Major Histocompatibility Complex Class I Proteins on the Cell Surface after Infection of Murine Cells by Pseudorabies Virus

After pseudorabies virus (PRV) infection of murine L929 cells, the cell surface expression of major histocompatibility complex (MHC) class I proteins changes such that the total amount of MHC class I molecules remains relatively constant but the levels of the individual alleles D(k) and K(k) vary. This is an active process involving at least three PRV gene products that act in an allele-specific manner such that cell surface expression of MHC class I D(k) is decreased and that of K(k) is increased. Our results indicate that an early gene product mediates the overall reduction in D(k) protein and a late gene product which is mutant in the attenuated PRV strain Bartha mediates the increase in K(k) protein. We provide additional evidence for a third gene product involved in the regulation of the synthesis of both the D(k) and K(k) proteins. In addition, we show that the early decrease in the D(k) protein is not due to a block in synthesis or processing of the complex through the secretory system.