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Molecular chaperones of the endoplasmic reticulum promote hepatitis C virus E2 protein production in plants

Description

Infections caused by the Hepatitis C Virus (HCV) are very common worldwide, affecting up to 3% of the population. Chronic infection of HCV may develop into liver cirrhosis and liver cancer which is among the top five of the most common cancers. Therefore, vaccines against HCV are under intense study…

Infections caused by the Hepatitis C Virus (HCV) are very common worldwide, affecting up to 3% of the population. Chronic infection of HCV may develop into liver cirrhosis and liver cancer which is among the top five of the most common cancers. Therefore, vaccines against HCV are under intense study in order to prevent HCV from harming people's health. The envelope protein 2 (E2) of HCV is thought to be a promising vaccine candidate because it can directly bind to a human cell receptor and plays a role in viral entry. However, the E2 protein production in cells is inefficient due to its complicated matured structure. Folding of E2 in the endoplasmic reticulum (ER) is often error-prone, resulting in production of aggregates and misfolded proteins. These incorrect forms of E2 are not functional because they are not able to bind to human cells and stimulate antibody response to inhibit this binding. This study is aimed to overcome the difficulties of HCV E2 production in plant system. Protein folding in the ER requires great assistance from molecular chaperones. Thus, in this study, two molecular chaperones in the ER, calreticulin and calnexin, were transiently overexpressed in plant leaves in order to facilitate E2 folding and production. Both of them showed benefits in increasing the yield of E2 and improving the quality of E2. In addition, poorly folded E2 accumulated in the ER may cause stress in the ER and trigger transcriptional activation of ER molecular chaperones. Therefore, a transcription factor involved in this pathway, named bZIP60, was also overexpressed in plant leaves, aiming at up-regulating a major family of molecular chaperones called BiP to assist protein folding. However, our results showed that BiP mRNA levels were not up-regulated by bZIP60, but they increased in response to E2 expression. The Western blot analysis also showed that overexpression of bZIP60 had a small effect on promoting E2 folding. Overall, this study suggested that increasing the level of specific ER molecular chaperones was an effective way to promote HCV E2 protein production and maturation.

ContributorsHong, Fan (Author) / Mason, Hugh (Thesis advisor) / Gaxiola, Roberto (Committee member) / Chang, Yung (Committee member) / Chen, Qiang (Committee member) / Arizona State University (Publisher)

Created2011

Measles Virus Vectoring Hepatitis C Non-structural Protein 3: Towards a Hepatitis C Vaccine

Description

Hepatitis C virus (HCV) is a globally prevalent infection which is a main contributor to the global burden of liver disease. Due to its ability to establish a chronic infection, and the lack of usefulness of traditional neutralizing antibody vaccine design in producing a protective immune response, a preventative vaccine…

Hepatitis C virus (HCV) is a globally prevalent infection which is a main contributor to the global burden of liver disease. Due to its ability to establish a chronic infection, and the lack of usefulness of traditional neutralizing antibody vaccine design in producing a protective immune response, a preventative vaccine has been notoriously difficult to produce. To overcome this, a vaccine using non-structural protein 3 (NS3) as a target to elicit a T cell specific immune response is thought to be a possible strategy for eliciting a protective immune response against hepatitis C infection. In this paper, a recombinant strain of measles virus (MV) that expresses HCV NS3 protein was analyzed. The replication fitness of this recombinant virus also indicates that this construct replicates at a higher rate than parental measles strain. It is also demonstrated through western blot analysis of protein expression and immunofluorescence that this recombinant virus expresses both the inserted HCV NS3 protein, as well as native measles proteins.

ContributorsWoell, Dana Marie (Author) / Reyes del Valle, Jorge (Thesis director) / Nickerson, Cheryl (Committee member) / Julik, Emily (Committee member) / Barrett, The Honors College (Contributor) / Department of Chemistry and Biochemistry (Contributor) / School of Human Evolution and Social Change (Contributor)

Created2015-05

Sex-biased gene expression and pathway activation in hepatitis-associated HCC.

Description

Hepatocellular Carcinoma (HCC) is one of the main types of liver cancer accounting for 75% of cases and is the second deadliest cancer worldwide. Chronic Hepatitis B (HBV) and Hepatitis C (HCV) remain one of the most important global risk factors and account for 80% of all HCC cases. HCC…

Hepatocellular Carcinoma (HCC) is one of the main types of liver cancer accounting for 75% of cases and is the second deadliest cancer worldwide. Chronic Hepatitis B (HBV) and Hepatitis C (HCV) remain one of the most important global risk factors and account for 80% of all HCC cases. HCC also exhibits sex-differences with significantly higher incidence and worse prognosis in males. The mechanistic basis of these sex-differences is poorly understood. To identify genes and pathways that are sex-differentially expressed in viral-mediated HCC, we performed differential expression analysis on tumor vs. tumor adjacent samples that were stratified based on sex, viral etiology, and both. The differentially expressed genes were then used in a pathway enrichment analysis to identify potential pathways of interest. We found differentially expressed genes in both sexes and both etiologies. 65 genes were unique to females and 184 genes unique to males. 381 genes are unique to HBV and 195 genes are unique to HCV. We also found pathways that were significantly enriched by the differentially expressed genes. Ten pathways unique to the female tumor tumor-adjacent comparison and a majority of those pathways were a part of the cell cycle. Four enriched pathways unique to male tumor tumor-adjacent and three of them were a part of the immune system. There were no pathways unique to either etiology, but seven pathways shared by both etiologies. Two were a part of the cell cycle and one involved lipid metabolism. These differentially expressed genes and significant pathways are potential targets for individualized therapeutics and diagnostics for HCC.

ContributorsJorgensen, Annika (Author) / Wilson, Melissa (Thesis director) / Buetow, Kenneth (Committee member) / Barrett, The Honors College (Contributor) / School of Life Sciences (Contributor) / Department of Physics (Contributor)

Created2023-05

The Ineffective Cure Hepatitis C and the Drug That Never Got Its Chance

Description

Hepatitis C is an infectious disease that affects 71 million people worldwide and causes liver failure and death if untreated. In 2013, a direct acting antiviral drug, sofosbuvir, revolutionized treatment of the disease. Sofosbuvir showed immense promise, but the high price point at which it was launched created access barriers…

Hepatitis C is an infectious disease that affects 71 million people worldwide and causes liver failure and death if untreated. In 2013, a direct acting antiviral drug, sofosbuvir, revolutionized treatment of the disease. Sofosbuvir showed immense promise, but the high price point at which it was launched created access barriers that prevented it from reaching its full public health potential. By 2016, fewer than 1% of Hepatitis C patients worldwide had received treatment. In the United States (US), concerns about the cost of the drug led public and private payers to implement rationing and treatment restrictions that prevented some of the most vulnerable populations from accessing Hepatitis C treatment at all. Through interviews with researchers, patients and providers, and a literature review of grants, patents, papers, court documents, and news articles, I examine the history of sofosbuvir with attention to the ways in which federal funding practices and intellectual property law encouraged the high initial pricing of the drug. I then examine the impact of this drug on healthcare systems in the United States and abroad, and discuss how the fragmented nature of the United States healthcare system has exacerbated price-based barriers to access. Finally, I discuss intellectual property laws as potential mechanisms to increase access. My study underscores how the political reluctance to use well-established federal funding and intellectual property laws has resulted in a drug development system that delivers medications that are so highly priced that the fragmented US healthcare system cannot compensate for the expense. This leads to low access and poor public health outcomes, and a continued failure to contain or control diseases for which effective therapies exist.

ContributorsTiffney, Theora (Author) / Cook-Deegan, Robert M. (Thesis advisor) / Collins, James P. (Thesis advisor) / Ross, Heather M (Committee member) / Chew, Matthew K (Committee member) / Arizona State University (Publisher)

Created2020