Polypeptide synthesis and phosphorylation in Epstein-Barr virus-infected cells

Abstract

Epstein-Barr virus superinfection of the human lymphoblastoid cell line Raji, a Burkitt lymphoma-derived line that contains Epstein-Barr virus genomes in an episomal form, results in the sequential synthesis of 29 detectable proteins, which range in molecular weight from approximately 155,000 to 21,000, and in the shutoff of the bulk of host protein synthesis within 6 to 9 h after infection. There are three classes of virus-induced proteins; these are an early class, consisting of eight proteins synthesized by 6 h postinfection, an intermediate class, containing two proteins synthesized 9 h postinfection, and a late class, consisting of five proteins synthesized 12 h postinfection. In addition, there is a fourth class of polypeptides, called persistent, that are found both before and after superinfection. The rates of synthesis of the proteins fall into three patterns; these are pattern A, in which the rate of synthesis decreases, pattemn B, in which the rate of synthesis remains steady, and pattern C, in which the rate of synthesis increases after the initial appearance of the polypeptide. Both 9-(2-hydroxyethoxymethyl)guanine (acyclovir) and phosphonoacetic acid inhibit the appearance of one intermediate protein and at least three late proteins. Seven polypeptides are phosphorylated at different times after infection.

Epstein-Barr virus RNA. VIII. Viral RNA in permissively infected B95-8 cells

“…EBV probably also has at least three classes of sequential protein synthesis (10)(11)(12). Some EBV polypeptides are expressed for transient intervals after induction or superinfection (10)(11)(12). The RNAs encoding these polypeptides would not have been detected in this study.…”

“…Third, other herpesvirus genomes have more elaborate regulatory schemes involving three tiers of sequential protein synthesis in productive infection (24). EBV probably also has at least three classes of sequential protein synthesis (10)(11)(12). Some EBV polypeptides are expressed for transient intervals after induction or superinfection (10)(11)(12).…”

“…In permissively infected cells, the complexity of polyadenylated RNA is similar to the full single-strand complexity of the EBV genome (38). More than 30 new polypeptides are synthesized in productively infected cells (10,11,25,26,(35)(36)(37). Only a few of these polypeptides are synthesized in Raji cells after induction (37).…”

Filamentous structures associated with Epstein-Barr virus-infected cells

“…The 3Hlabeled DNA profiles of both gradients are plotted together in Fig. 4 after alignment of the 1^i protein synthesis and the subsequent appearance of viral-induced polypeptides (10). Proteins labeled at 36 to 48 h after infection were recovered from a metrizamide gradient, such as the one shown in Fig.…”

“…In Raji cells, all of the viral genomes are present as circular, superhelical molecules (1,20) and exhibit a regular micrococcal nuclease digestion pattern typical of the host cell chromatin (32). Superinfection of Raji cells with EBV results in an abortive process involving the synthesis of several thousand copies of viral DNA per cell (33) and the induction of virus-specific proteins (10), but the release of only a few mature virions (31,36). As in the virus-producing cell lines, the viral nucleoproteins produced during this superinfection are not organized into nucleosome-like structures when examined by micrococcal nuclease digestion (32).…”