Glycoprotein 110, the Epstein-Barr virus homolog of herpes simplex virus glycoprotein B, is essential for Epstein-Barr virus replication in vivo

Abstract

The Epstein-Barr virus (EBV) glycoprotein gp110 has substantial amino acid homology to gB of herpes simplex virus but localizes differently within infected cells and is essentially undetectable in virions. To investigate whether gp110, like gB, is essential for EBV infection, a selectable marker was inserted within the gp110 reading frame, BALF4, and the resulting null mutant EBV strain, B95-110HYG, was recovered in lymphoblastoid cell lines (LCLs). While LCLs infected with the parental virus B95-8 expressed the gp110 protein product following productive cycle induction, neither full-length gp110 nor the predicted gp110 truncation product was detectable in B95-110HYG LCLs. Infectious virus could not be recovered from B95-110HYG LCLs unless gp110 was provided in trans. Rescued B95-110HYG virus latently infected and growth transformed primary B lymphocytes. Thus, gp110 is required for the production of transforming virus but not for the maintenance of transformation of primary B lymphocytes by EBV.

Receptor-Binding Properties of a Soluble Form of Human Cytomegalovirus Glycoprotein B

“…Genetic deletions, or knockouts, have proven very useful in determining the essentialness of individual genes. To this end, all gB molecules examined to date, including that of HCMV, have been demonstrated to be essential components in the replication cycle (4,10,21,41). More recently, viral recombinants containing different gBs have been used to identify crosscomplementation.…”

The Epstein-Barr virus glycoprotein 110 carboxy-terminal tail domain is essential for lytic virus replication

“…1). Two of the constructs, DM(1-816) and DM(1-801), were constructed by insertion of an XbaI linker containing stop codons in all three reading frames into unique restriction sites within the region encoding the gp110 tail contained in a previously described gp110 expression vector, pSVgp110 (15). For DM , the XbaI linker was inserted into a unique EagI site, which results in termination of gp110 after 816 amino acids; this removed 41 amino acids from the 104-amino-acid gp110 carboxyl-terminal tail.…”

“…Expression of the gp110 tail deletion mutants in EBV (gp110؊) ؉ LCLs. Expression of the gp110 truncation mutants was verified by transfection followed by immunoprecipitation in a previously described EBV(gp110Ϫ) ϩ LCL designated M.2, in which the gp110 coding domain has been interrupted by a cassette expressing the hygromycin phosphotransferase gene driven by the simian virus 40 early promoter (SVHYG) (15). The insertion results in the complete absence of expression of gp110 in EBV(gp110Ϫ) ϩ LCLs (15).…”

“…Antibodies currently available and directed against gp110 fail to neutralize EBV infectivity (10). Although gp110 and gB have been shown to be essential for viral replication (3,15), the unique features of gp110 may indicate that it has a different role from gB in viral infection.…”

The Epstein-Barr Virus (EBV) gN Homolog BLRF1 Encodes a 15-Kilodalton Glycoprotein That Cannot Be Authentically Processed unless It Is Coexpressed with the EBV gM Homolog BBRF3

“…Glycoprotein gp85, the EBV gH (8,22), glycoprotein gp25, the EBV gL (31), and glycoprotein gp110, the EBV gB (6), have all been characterized biochemically and functionally, and a mixed picture is emerging when their behavior is compared to that of their counterparts in other herpesviruses. The EBV gB is not a major virion component as it is in many herpesviruses but, rather, is localized primarily to the nuclear membrane of virion-producing cells (5), and although in many herpesviruses gB is critical to virus entry, in EBV it plays a major role in virus assembly (9,14). In contrast, although the EBV gH-gL complex includes a third poorly conserved but functionally important glycoprotein gp42 (18), in general it behaves like that of other herpesviruses.…”