Differentiation-associated expression of the Epstein-Barr virus BZLF1 transactivator protein in oral hairy leukoplakia

Abstract

The BZLF1 protein of Epstein-Barr virus (EBV) is a key immediate-early protein which has been shown to disrupt virus latency in EBV-infected B cells. We have generated a monoclonal antibody, BZ1, to BZLF1 which reacts in immunohistology, immunoblotting, and immunoprecipitation and which recognizes both the active, dimeric form and the inactive, monomeric form of the protein. Biopsies of oral hairy leukoplakia, an AIDS-associated lesion characterized by high-level EBV replication, were examined by immunohistochemistry using the BZ1 monoclonal antibody. A differentiation-associated pattern of BZLF1 expression was observed, BZ1 reacting with nuclei of the upper spinous layer of the lesion. This finding suggests that the BZLF1 promoter may be regulated by the degree of squamous differentiation. A comparison of in situ hybridization to EBV DNA and viral capsid antigen staining with BZ1 reactivity suggested that BZLF1 expression precedes rampant virus replication. The inability to detect EBV in the lower epithelial layers of oral hairy leukoplakia raises questions concerning the nature of EBV latency and persistence in stratified squamous epithelium.

Epstein–Barr virus (EBV)‐positive pyothorax‐associated lymphoma (PAL): chromosomal integration of EBV in a novel CD2‐positive PAL B‐cell line

“…The sensitivity of this analysis was confirmed by detecting the BZLF1 mRNA in an EBV-producing lymphoblastoid cell line (LCL) established from a healthy donor by infecting B cells with EBV in vitro. Moreover, ZEBRA protein was not detectable by Western blot analysis using a mAb to ZEBRA, BZ.1 (Young et al, 1991) (data not shown). Thus, the lack of ZEBRA production indicated that EBV did not replicate in Pal-1 cells.…”

Hairy leukoplakia; lessons learned: 30‐plus years

“…As HL is the only pathological manifestation of EBV permissive replication, there followed many studies exploring the opportunities presented by the fully replicative nature of EBV infection of oral epithelial cells in the lesion. These include the following: showing defective DNA (Patton et al, 1990); high level EBV replication; multiple EBV strains; inter-and intrastrain recombination (Walling et al, 1995), absence of latent phase EBV DNA and proteins in HL basal epithelium (Niedobitek et al, 1991;Young et al, 1991;Murray et al, 1996;Cruchley et al, 1997), new EBV genes such as BMRF-2, BFRF1 and BDLF-3 (Palefsky et al, 1997;Penaranda et al, 1997;Farina et al, 2004); as well as evidence for trafficking of Epstein-Barr virus strains between hairy leukoplakia and peripheral blood lymphocytes (Palefsky et al, 2002). These and other aspects of the biology of HL and EBV are reviewed in more detail by Webster-Cyriaque (submitted 2015).…”

The Epstein-Barr virus bZIP transcription factor Zta causes G0/G1 cell cycle arrest through induction of cyclin-dependent kinase inhibitors.

“…Although the EBV lytic cycle can be activated in B-cells, replication of EBV in vivo occurs primarily in epithelial cells of the oropharynx, salivary glands and uterine cervix (Sixbey et al, 1984(Sixbey et al, , 1986Wolf et al, 1984). Full EBV replication appears to be highly dependent on the differentiated state of the epithelium since it is observed in the upper spinous layer which contains cells that have stopped dividing, but not in the basal, mitotically active layer (Wolf et al, 1984;Becker et al, 1991;Young et al, 1991). In agreement with these observations of EBV replication in growth-arrested, differentiated cells in vivo, it has been shown in vitro that replication of EBV, as well as other herpes viruses, can occur in cells treated with agents shown previously to arrest cell cycle progression (Shadan et al, 1994).…”