Epstein-Barr virus (EBV) infection is associated with B-cell lymphomas and oral hairy leukoplakia (particularly in AIDS patients), as well as nasopharyngeal carcinoma (NPC) and gastric cancer. Recent findings from our lab indicate that lytically-infected cells secrete cytokines and other factors that may promote growth of tumor cells in vivo. In addition, increasing evidence suggests that a secreted viral protein, BARF1 (which was previously reported to be a decoy receptor for the macrophage differentiation factor, CSF-1), plays a critical role in the etiology of EBV+ epithelial cancers, and may also contribute to Burkitt lymphomas (BL). Although the switch from latent to lytic infection is thought to be mediated by the BZLF1 (Z) and BRLF1(R) proteins, we have discovered that expression of another viral protein, BRRF1 (Na), is sufficient to induce the lytic form of infection in latently infected NPC and gastric cancer cells. In addition, our new preliminary data suggest that BARF1 inhibits lytic viral gene expression in epithelial cells, while CSF-1 signaling enhances lytic gene expression. Therefore, BARF1 may inhibit lytic reactivation by blocking CSF-1-mediated lytic induction. Thus, regulation of Na transcription, as well as Na and BARF1 function, must play key roles in determining if EBV infection in epithelial cells is latent or lytic. To study the roles of specific EBV proteins such as Na and BARF1 in viral pathogenesis, we have developed a new mouse model (engrafted with a reconstituted human immune system in the presence or absence of a human thymus) that supports both latent and lytic infection, as well as lymphomas, in EBV-infected mice. Based upon our exciting preliminary data, we propose the following aims.
In Aim 1, we will examine the in vitro phenotype of a Na-mutant virus in B cells versus epithelial cells, and elucidate the mechanism(s) by which Na mediates viral reactivation in epithelial cells.
In Aim 2, we will define the viral and cellular factors that regulate Na transcription in the presence and absence of promoter methylation, and determine if Na is an IE or early gene in different cell types.
In Aim 3, we will explore how CSF-1 and BARF1 regulate viral reactivation and growth of EBV-infected cells in vitro, and determine if BARF1 promotes the growth of EBV- positive epithelial tumors in SCID mice.
In Aim 4, we will define the in vivo phenotypes of the Na and BARF1 mutant viruses in our new mouse model containing an engrafted human immune system. The proposed studies should yield important insights into how the switch from latent to lytic infection is regulated in B cells versus epithelial cells, and define the multiple roles that lytic EB proteins play in EBV-associated diseases.

Public Health Relevance

Epstein-Barr virus infection in AIDS patients causes both B cell lymphomas and a lesion on the tongue known as oral hairy leukoplakia. The proposed research will use a new mouse model to examine how Epstein-Barr virus can be converted from the latent to active form in B cells versus epithelial cells, and contributes to both B cell and epithelial cell malignancies. The results of these studies may lead to new treatments for AIDS-related lymphomas and oral hairy leukoplakia.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
5R01CA058853-20
Application #
8446169
Study Section
AIDS-associated Opportunistic Infections and Cancer Study Section (AOIC)
Program Officer
Daschner, Phillip J
Project Start
1993-08-01
Project End
2014-02-28
Budget Start
2013-03-01
Budget End
2014-02-28
Support Year
20
Fiscal Year
2013
Total Cost
$267,781
Indirect Cost
$87,457
Name
University of Wisconsin Madison
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
161202122
City
Madison
State
WI
Country
United States
Zip Code
53715
Kenney, Shannon C; Mertz, Janet E (2014) Regulation of the latent-lytic switch in Epstein-Barr virus. Semin Cancer Biol 26:60-8
Wille, Coral K; Nawandar, Dhananjay M; Panfil, Amanda R et al. (2013) Viral genome methylation differentially affects the ability of BZLF1 versus BRLF1 to activate Epstein-Barr virus lytic gene expression and viral replication. J Virol 87:935-50
Raver, Ryan M; Panfil, Amanda R; Hagemeier, Stacy R et al. (2013) The B-cell-specific transcription factor and master regulator Pax5 promotes Epstein-Barr virus latency by negatively regulating the viral immediate early protein BZLF1. J Virol 87:8053-63
Robinson, Amanda R; Kwek, Swee Sen; Kenney, Shannon C (2012) The B-cell specific transcription factor, Oct-2, promotes Epstein-Barr virus latency by inhibiting the viral immediate-early protein, BZLF1. PLoS Pathog 8:e1002516
Hagemeier, Stacy R; Barlow, Elizabeth A; Kleman, Ariel A et al. (2011) The Epstein-Barr virus BRRF1 protein, Na, induces lytic infection in a TRAF2- and p53-dependent manner. J Virol 85:4318-29
Ma, Shi-Dong; Hegde, Subramanya; Young, Ken H et al. (2011) A new model of Epstein-Barr virus infection reveals an important role for early lytic viral protein expression in the development of lymphomas. J Virol 85:165-77
Shaffer, Donald R; Savoldo, Barbara; Yi, Zhongzhen et al. (2011) T cells redirected against CD70 for the immunotherapy of CD70-positive malignancies. Blood 117:4304-14
Robinson, Amanda R; Kwek, Swee Sen; Hagemeier, Stacy R et al. (2011) Cellular transcription factor Oct-1 interacts with the Epstein-Barr virus BRLF1 protein to promote disruption of viral latency. J Virol 85:8940-53
Sun, Xiaoping; Kenney, Shannon C (2010) Hsp90 inhibitors: a potential treatment for latent EBV infection? Cell Cycle 9:1665-6
Hagemeier, Stacy R; Dickerson, Sarah J; Meng, Qiao et al. (2010) Sumoylation of the Epstein-Barr virus BZLF1 protein inhibits its transcriptional activity and is regulated by the virus-encoded protein kinase. J Virol 84:4383-94

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