Bortezomib Inhibits Hepatitis B Virus Replication in Transgenic Mice

ABSTRACT Pharmacological modulation of cellular proteins as a means to block virus replication has been proposed as an alternative antiviral strategy that may be less susceptible than others to the development of viral drug resistance. Recent evidence indicates that the ubiquitin-proteasome pathway interacts with different aspects of the hepatitis B virus (HBV) life cycle in cell culture models of virus replication. We therefore examined the effect of proteasome inhibition on HBV replication in vivo using HBV transgenic mice. The proteasome inhibitor bortezomib (Velcade) inhibits proteasome activity in vivo and is used therapeutically for the clinical treatment of multiple myeloma. We found that a single intravenous dose of 1 mg of bortezomib/kg of body weight reduced virus replication for as long as 6 days. The inhibition of HBV by bortezomib was dose dependent and occurred at a step in replication subsequent to viral RNA and protein expression. The reduction in HBV replication did not result from nonspecific hepatocellular toxicity and was not mediated indirectly through the induction of an intrahepatic interferon response. Thus, pharmacological manipulation of the ubiquitin-proteasome pathway may represent an alternative therapeutic approach for the treatment of chronic HBV infection.

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Inhibition of Cellular Proteasome Activities Mediates HBX-Independent Hepatitis B Virus Replication In Vivo

Journal of Virology ◽

10.1128/jvi.00579-10 ◽

2010 ◽

Vol 84 (18) ◽

pp. 9326-9331 ◽

Cited By ~ 13

Author(s):

Zhensheng Zhang ◽

Eun Sun ◽

Jing-hsiung James Ou ◽

T. Jake Liang

Keyword(s):

Hepatitis B Virus ◽

Hepatitis B ◽

Transgenic Mice ◽

Productive Infection ◽

Minor Effect ◽

Hbv Replication ◽

B Virus ◽

Culture Models ◽

A Minor

ABSTRACT The X protein (HBX) of the hepatitis B virus (HBV) is essential for HBV productive infection in vivo. Our previous study (Z. Hu, Z. Zhang, E. Doo, O. Coux, A. L. Goldberg, and T. J. Liang, J. Virol. 73:7231-7240, 1999) shows that interaction of HBX with the proteasome complex may underlie the pleiotropic functions of HBX. Previously, we demonstrated that HBX affects hepadnaviral replication through a proteasome-dependent pathway in cell culture models. In the present study, we studied the effect of the proteasome inhibitor MLN-273 in two HBV mouse models. We demonstrated that administration of MLN-273 to transgenic mice containing the replication-competent HBV genome with the defective HBX gene substantially enhanced HBV replication, while the compound had a minor effect on wild-type HBV transgenic mice. Similar results were obtained by using C57BL/6 mice infected with recombinant adenoviruses expressing the replicating HBV genome. Our data suggest that HBV replication is subjected to regulation by cellular proteasome and HBX functions through the inhibition of proteasome activities to enhance HBV replication in vivo.

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Enhancement of Hepatitis B Virus Replication by the Regulatory X Protein In Vitro and In Vivo

Journal of Virology ◽

10.1128/jvi.02020-06 ◽

2006 ◽

Vol 81 (6) ◽

pp. 2656-2662 ◽

Cited By ~ 112

Author(s):

Victor V. Keasler ◽

Amanda J. Hodgson ◽

Charles R. Madden ◽

Betty L. Slagle

Keyword(s):

Hepatitis B Virus ◽

Hepatitis B ◽

Virus Replication ◽

Hepg2 Cells ◽

Wild Type ◽

Tail Vein ◽

Hbv Replication ◽

Tail Vein Injection ◽

B Virus

ABSTRACT The 3.2-kb hepatitis B virus (HBV) genome encodes a single regulatory protein termed HBx. While multiple functions have been identified for HBx in cell culture, its role in virus replication remains undefined. In the present study, we combined an HBV plasmid-based replication assay with the hydrodynamic tail vein injection model to investigate the function(s) of HBx in vivo. Using a greater-than-unit-length HBV plasmid DNA construct (payw1.2) and a similar construct with a stop codon at position 7 of the HBx open reading frame (payw1.2*7), we showed that HBV replication in transfected HepG2 cells was reduced 65% in the absence of HBx. These plasmids were next introduced into the livers of outbred ICR mice via hydrodynamic tail vein injection. At the peak of virus replication, at 4 days postinjection, intrahepatic markers of HBV replication were reduced 72% to 83% in mice injected with HBx-deficient payw1.2*7 compared to those measured in mice receiving wild-type payw1.2. A second plasmid encoding HBx was able to restore virus replication from payw1.2*7 to wild-type levels. Finally, viremia was monitored over the course of acute virus replication, and at 4 days postinjection, it was reduced by nearly 2 logs in the absence of HBx. These studies establish that the role for HBx in virus replication previously shown in transfected HepG2 cells is also apparent in the mouse liver within the context of acute hepatitis. Importantly, the function of HBx can now be studied in an in vivo setting that more closely approximates the cellular environment for HBV replication.

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Virus replication and virion export in X-deficient hepatitis B virus transgenic mice

Journal of General Virology ◽

10.1099/0022-1317-83-5-991 ◽

2002 ◽

Vol 83 (5) ◽

pp. 991-996 ◽

Cited By ~ 25

Author(s):

Kurt Reifenberg ◽

Petra Nusser ◽

Jürgen Löhler ◽

Gabriele Spindler ◽

Christa Kuhn ◽

...

Keyword(s):

Hepatitis B Virus ◽

Hepatitis B ◽

Transgenic Mice ◽

Gene Product ◽

Core Protein ◽

Viral Genomes ◽

Hbv Replication ◽

B Virus ◽

High Level

The function of the X protein (pX) in the replication cycle of mammalian hepadnaviruses is enigmatic. Using tissue culture experiments it has been shown that the X gene product is not central to hepatitis B virus (HBV) replication and virion export. However, at present it is still unclear whether this also applies to the in vivo situation. Using a terminally redundant X-deficient HBV DNA construct, transgenic mice were established that exhibited high-level expression of the viral core protein in liver and kidneys. Importantly, replicative DNA intermediates and mature viral genomes could be detected in the liver and serum of these mice, respectively. These findings indicate that, in the in vivo model of transgenic mice, the HBV X (HBx) gene product is not required for HBV replication and virion secretion.

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