Early functions of the genome of herpesvirus: II. Inhibition of the formation of cell-specific polysomes

Abstract

During the early stages of infection of rabbit kidney cells with pseudorabies virus, when both cell- and virus-specific proteins are being synthesized, two types of polysomes are present in the infected cells: larger virus-specific polysomes with nascent chains of polypeptides characterized by a low lysine: leucine ratio, and smaller cell-specific polysomes with nascent chains of polypeptides characterized by a high lysine: leucine ratio. This finding demonstrates that virus-specific proteins have a lower content of lysine than cell-specific proteins. The difference between cell- and virus-specific proteins in their relative content of amino acids was used to monitor the types of proteins synthesized by the infected cells in studies on the mechanism controlling the shutoff of host protein synthesis in virus-infected cells. Both RNA and protein synthesis are required in the infected cells to effect the inhibition of cell-specific protein synthesis. It was found that a protein (or proteins) is synthesized in virus-infected cells which is responsible for the disappearance of cell-specific polysomes; the message for this protein is transcribed in cells infected in the presence of cycloheximide and is translated after the removal of cycloheximide.