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Journal of Virology, June 1999, p. 5214-5219, Vol. 73, No. 6
Department of Microbiology, Nihon University
School of Medicine, Oyaguchikami-machi, Itabashi-ku, Tokyo
173-8610, Japan
Received 4 December 1998/Accepted 16 March 1999
The Burkitt's lymphoma (BL) cell line Akata retains the latency I
program of Epstein-Barr virus (EBV) gene expression and cross-linking
of its surface immunoglobulin G (IgG) by antibodies results in
activation of viral replication. When EBV nuclear antigen 2 (EBNA2) was
artificially expressed by a constitutive expression vector, the Cp EBNA
promoter remained inactive and accordingly the latency III program was
not induced. In contrast, expression of LMP2A and activity of the Fp
lytic promoter were activated. Consistent with this Fp activity, the
rate of spontaneous activation of the EBV replicative cycle was
increased significantly, suggesting the possibility that EBNA2 can
induce EBV replication. The efficiency of anti-IgG-induced activation
of the viral replication was reduced in Akata cells expressing EBNA2.
To obtain more direct evidence for EBNA2-induced activation of the EBV
replicative cycle, this protein was next expressed by a
tetracycline-regulated expression system. EBNA2 was undetectable with
low doses (<0.5 µg/ml) of tetracycline, while its expression was
rapidly induced after removal of the antibiotic. This induced
expression of EBNA2 was immediately followed by expression of EBV
replicative cycle proteins in up to 50% of the cells, as shown by
indirect immunofluorescence and immunoblot analysis. These results
suggest an unexpected potential of EBNA2 to disrupt EBV latency and to
activate viral replication.
0022-538X/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
Epstein-Barr Virus (EBV) Nuclear Protein 2-Induced Disruption
of EBV Latency in the Burkitt's Lymphoma Cell Line Akata: Analysis
by Tetracycline-Regulated Expression

*
Corresponding author. Mailing address: Department of
Microbiology, Nihon University School of Medicine, Oyaguchikami-machi, Itabashi-ku, Tokyo 173-8610, Japan. Phone: 81-3-3972-8111, ext. 2263. Fax: 81-3-3972-9560. E-mail: shige{at}med.nihon-u.ac.jp.
Present address: Department of Pediatrics, Surugadai Hospital,
Nihon University School of Medicine, Kandasurugadai, Chiyoda-ku, Tokyo
101-8309, Japan.
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