Many viruses have evolved mechanisms to antagonize the interferon (IFN) system, targeting all the major components involved in receptor binding and signalling. Although a number of these viral proteins are homologous to cellular proteins involved in IFN downregulation (e.g., viral IFN regulatory factors [vIRFs]), many share little resemblance to known proteins. To determine the IFN-blocking properties of these proteins, functional assays are required. Here, we present a new and rapid functional screening method, based on the 2FTGH cell line, which is able to determine viral gene products that inhibit the IFN-alpha/Jak-Stat signalling pathway. Expression cloning of viral IFN-blocking genes into 2FTGH and consequent selection with IFN-alpha and 6-thioguanine result in the outgrowth of cells that are no longer responsive to IFN-alpha. We also demonstrate that selection occurs if members of the Jak-Stat signalling pathway are lost. To show the utility of our system, we have used a known suppressor of IFN signalling, the human papillomavirus (HPV) E7 gene. Expression of E7 causes the loss of ability of 2FTGH cells to respond to IFN-alpha treatment because of a functional disruption of the signalling pathway. This approach offers a new strategy for identifying novel viral genes or new functions of already described viral genes that have a role in IFN-alpha signalling inhibition.

[Truncated abstract] Hepatic progenitor cells (HPC) are becoming increasingly recognized as facultative stem cells capable of regenerating the liver during chronic liver injury and also as targets of malignant transformation. Similar markers are expressed by hepatocellular carcinoma (HCC) and HPC, and a precursor-product relationship is well established. This thesis focuses on the ways in which the HPC population can be controlled under circumstances of chronic liver injury, and in this manner, reduce the risk of progression to HCC reduced. The major aim of Chapters 3 to 5 was to elucidate the effect of interferon α (IFNα) therapy on HPC. Chronic hepatitis C affects approximately 250 million individuals world wide. Approximately 80% of infections progress to chronicity, which places the individuals at greater risk of developing HCC. The gold standard of treatment of chronic hepatitis C is a combination of pegylated IFNα and ribavirin. ...The results were surprising. While IFNγ exerted a pro-apoptotic and antiproliferative effect on HPC in vitro, administration of IFNγ to CDE-fed mice for 14 days increased fibrosis, enhanced inflammatory infiltration and exacerbated the HPC response, with concurrent hepatocyte cell death. In addition, increased morbidity and mortality were observed in the IFNγ-treated mice compared to control. IFNγ treatment was found to prime the liver for the HPC response by recruiting inflammatory cells and altering the hepatic cytokine profile, both of which may facilitate an increased HPC response. Numbers of activated HSC were also increased in the IFNγ-treated, CDE-fed mice, correlating with the increased fibrosis seen in these animals. This data contradicts the current experimental use of IFNγ for treatment of fibrosis. Based on our results, we suggest that IFNγ promotes HPC proliferation in the CDE model, by encouraging inflammatory infiltration and hepatocyte damage and this initiates pro-fibrotic events. Concurrent proliferation of HPC and activated HSC further supports the view that there is a close relationship between the two cell types, and thus, a link between the HPC response and fibrosis. In conclusion, findings documented in this thesis suggest that administration of IFNα and IFNγ can contribute to shaping the HPC response. IFNα therapy may reduce HCC risk in chronic hepatitis C patients by bringing the HPC population under control. In contrast, IFNγ treatment can exacerbate the HPC response, liver fibrosis and parenchymal damage, illustrating the need to approach this method of fibrosis treatment with caution.

Diss. (sammanfattning) Stockholm : Karolinska institutet, 2007. / Härtill 4 uppsatser.

Thesis (Ph. D.)--University of Texas Southwestern Medical Center at Dallas, 2006. / Vita. Includes bibliographical references (p. 170-180).

Thesis (Ph.D. in Cancer Biology) -- University of Colorado at Denver and Health Sciences Center, 2006. / Typescript. Includes bibliographical references (leaves 112-124). Free to UCDHSC affiliates. Online version available via ProQuest Digital Dissertations;

Diss. (sammanfattning) Stockholm : Karol inst., 2003. / Härtill 5 uppsatser.

Diss. (sammanfattning) Stockholm : Karol. inst., 2002. / Härtill 4 uppsatser.

Diss. (sammanfattning) Stockholm : Karol. inst., 2002. / Härtill 5 uppsatser.

Diss. (sammanfattning) Stockholm : Karol. inst., 2005. / Härtill 4 uppsatser.

Diss. (sammanfattning) Linköping : Linköpings universitet, 2006. / Härtill 4 uppsatser.