Transfection of a rearranged viral DNA fragment, WZhet, stably converts latent Epstein-Barr viral infection to productive infection in lymphoid cells.

Abstract

An Epstein-Barr viral gene (ZEBRA) is identified that, in human lymphoblastoid cells, activates a switch causing the virus to shift from the latent to the replicative phase of its life cycle. We have shown that a 2.7-kilobase-pair rearranged Epstein-Barr virus DNA fragment of this gene (BamHI fragment WZhet) induced transient expression of viral replicative antigens and polypeptides when it was transfected into a somatic cell hybrid, which was derived from the fusion of an epithelial line cell with a Burkitt lymphoma cell. We now show that this rearranged WZhet fragment, when introduced stably into lymphoblastoid cells, will activate expression of the complete viral replicative cycle in 1-10% of the lymphoblastoid cells, leading to production of biologically active virions that can immortalize primary lymphocytes. The transfected plasmid appears to be regulated in a manner analogous to the complete Epstein-Barr virus genome.

DNA-binding-defective mutants of the Epstein-Barr virus lytic switch activator Zta transactivate with altered specificities.

“…Activation of the lytic cascade by treatment with anti-immunoglobulin results initially in the expression of two viral genes, BZLF1 and BRLF1, which exhibit similar induction kinetics (maximal mRNA levels are reached between 2 and 4 h postinduction) (14, 46). The protein products of both the BZLF1 (referred to here as Zta, but also called ZEBRA and EB1) and BRLF1 (Rta) genes have been shown to be transcriptional activators (8,10,12,25,26 speck@visar.wustl.edu.Expression of Zta and Rta leads to the activation of early genes and ultimately viral replication. Of all the viral transactivators examined, Zta is unique in that its expression alone can initiate the entire lytic cascade (10,11,40), and regulation of Zta expression appears to be central to regulating entry into the lytic cycle.…”

“…Activation of the lytic cascade by treatment with anti-immunoglobulin results initially in the expression of two viral genes, BZLF1 and BRLF1, which exhibit similar induction kinetics (maximal mRNA levels are reached between 2 and 4 h postinduction) (14,46). The protein products of both the BZLF1 (referred to here as Zta, but also called ZEBRA and EB1) and BRLF1 (Rta) genes have been shown to be transcriptional activators (8,10,12,25,26). speck@visar.wustl.edu.…”

High levels of Epstein-Barr virus in COPD

“…Epstein-Barr virus (EBV) is a member of the herpes virus family, which is widespread and has been associated with a variety of disease processes, including glandular fever, Burkitt's lymphoma, nasopharyngeal carcinoma, lymphoma and post-transplant lymphoproliferative disease [6][7][8][9]. Burkitt's lymphoma and nasopharyngeal carcinoma are both associated with latent EBV infection [10,11].…”

Epstein-barr virus immortalization and latency

“…which acts as EBV's immediate early transcriptional activator. (17,70,137,190,191). Derepression of the BZLF1 gene probably underlies the action of most chemical and physical inducers of lytic replication and the mechanism is commonly referred to as the latent/lytic switch.…”