Hepatitis C virus (HCV) represents a global health threat. HCV is a blood-borne positive-strand RNA virus belonging to the Flaviviridae family that infects ~160 million people worldwide. About 70% of infected individuals fail to clear the virus and subsequently develop chronic hepatitis, frequently leading to liver cirrhosis and in some cases hepatocellular carcinoma. Therapeutic options for HCV infection are still limited and a protective vaccine is not yet available. Currently available therapies include administration of pegylated alpha interferon in combination with ribavirin. The recently approved protease inhibitors Boceprevir and Telaprevir are also included in the treatment regimen. However, limitations to the treatment with direct-acting antivirals (DAAs) are associated with severe side effects and low sustained virological response (SVR) rates that vary depending on the virus and host genotype. The replication step of the viral life cycle is mostly targeted by majority of DAAs. Recent findings have suggested that a combination of entry inhibitors together with DAAs exhibit a synergistic effect in the treatment of HCV. Therefore, identification of efficient HCV entry inhibitors is of high priority In vitro studies have shown that HCV attachment and subsequent entry into the host cells is mediated by E1 and E2 viral envelope proteins. HCV entry requires interaction with a number of receptors which include CD81, scavenger receptor B1 (SR-B1) and the tight junction proteins, claudin 1 (CLDN1) and occludin (OCLN). Since the E2 glycoprotein is reported to interact directly with cellular receptors, it is an attractive target for neutralisation. The present study focuses on the establishment and characterisation of entry inhibitors as antivirals for HCV. The thesis is presented in three chapters: Chapter 1- ‘Introduction’, provides a brief overview on HCV genotypes, genome organisation, life cycle including details on the entry process and therapies used for the treatment of HCV. Chapter 2 describes the generation of monoclonal antibodies (mAbs) against HCV envelope proteins as potent anti-viral agents for the prevention of HCV infection. Data on the identification and characterization of the neutralizing epitopes of HCV envelope proteins have been presented. Chapter 3 includes isolation of entry inhibitors of HCV from natural sources and identification and characterization of the active components exhibiting antiviral property. A number of studies have reported the role of neutralizing antibodies in the course of HCV infection and emerging data suggest protective effect of antibodies against HCV infection. Most of the ongoing studies are based on HCV genotype 1a which is prevalent globally. However in India, the prevalent genotype is 3a. Therefore, we established a panel of mAbs against HCV-LPs comprising of core-E1-E2 derived from genotype 3a as described in chapter 2. HCV-LP based system has been used in this study since it mimics the biophysical conformation, morphology and antigenic properties of the native virion and represents a model system for studies on viral binding and entry. MAbs were characterised and analyzed for their ability to prevent viral binding and entry into host cells. Three mAbs namely E3D8, H6D3 and A10F2 were identified to recognize the E2 viral glycoprotein which significantly inhibited HCV-LP binding to Huh7 cells in vitro. The neutralizing epitopes corresponding to the mAbs were identified using overlapping truncated fragments and synthetic peptides of the E2 protein. Our experiments suggest that the epitopes recognised by the inhibitory mAbs are unique and different from those reported till now. The synergistic effect of a combination of mAbs on virus neutralization has shown promising results for treatment of viral infections. Since in the present study the epitopes recognised by the mAbs are non-overlapping, we went ahead to determine whether a combination of these mAbs would enhance the ability to block HCV-LP binding. Indeed, flow cytometry and fluorescence microscopy studies revealed that a combination of the antibodies efficiently blocked the binding of HCV-LP to human hepatoma cells. More importantly and of relevance is the observation that the mAbs in combination inhibited viral infection (JFH1 strain) and replication in permissive human hepatocytes as determined by real time RT-PCR. Phytochemicals present in plants have been considered as conducive for prevention of several viral infections and are found to be promising antiviral agents. Natural products which are biologically active disclose drug-like properties since they are small molecules and can be easily metabolised and absorbed by the body. In our study as described in chapter 3, we evaluated extracts from Indian medicinal plants and fruits which are known to have hepato-protective effect, for natural potent attachment and entry inhibitors for HCV. Flow cytometric analysis suggested that the root extract of the herb Boerhavia diffusa and fruit extract of Prunus domestica exhibited high antiviral activity by inhibiting the binding of Hepatitis C virus like particles (HCV-LPs) to the human hepatoma cells. We went on to isolate, identify and confirm the active principles to be Boeravinone H, a dehydrorotenoid, (from Boerhavia diffusa) and Rutin, a flavonoid, (from Prunus domestica) by LC-ESI-MS, NMR, UV and IR spectral analysis. Our study revealed that the compounds block the attachment as well as entry step probably by targeting the viral particle. We also assessed the efficiency of these small molecules (Boeravinone H and Rutin) to inhibit HCV negative strand synthesis post entry by real time RT-PCR. Results suggest significant inhibition of viral entry and infection in the HCV cell culture (ex vivo). To our knowledge it is the first report on Boeravinone H and Rutin as entry inhibitor for HCV. In conclusion, our findings support the potential of employing a cocktail of neutralizing mAbs and antiviral agents from natural source in the management of HCV infection.

Ho Kar Fai, William. / Thesis submitted in: July 2002. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2003. / Includes bibliographical references (leaves 121-129). / Abstracts in English and Chinese. / Abstract --- p.I / Acknowledgement --- p.V / Table of Contents --- p.VI / Abbreviations --- p.VIII / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- The recent situation of hepatitis B infection and HBV-induced HCC in Hong Kong / Chapter 1.2 --- Natural history of HBV infection in human / Chapter 1.3 --- The genomic organization of HBV / Chapter 1.4 --- Potential oncogenic mechanism of HBV-induced hepatocarcinogenesis / Chapter 1.5 --- Aim of the present study / Chapter Chapter 2 --- Materials and methods --- p.16 / Chapter 2.1 --- Transformation in E.coli for subtracted normal-counterpart library / Chapter 2.2 --- PCR amplification of subtracted clones / Chapter 2.3 --- Sequencing of subtracted clones with dye-terminator cycle sequencing technology / Chapter 2.4 --- Sequence analysis and database construction / Chapter 2.5 --- Molecular cloning and characterization of novel gene / Chapter 2.6 --- In silico structural and functional analysis of Z313 / Chapter 2.7 --- Cloning and sequencing analysis of zinc finger protein 313 (Z313) / Chapter 2.7.1 --- PCR amplification of target gene -Z313 / Chapter 2.7.2 --- Mini-preparation of plasmid DNA / Chapter 2.7.3 --- Cycle sequencing of cloned cDNA -Z313 with dye-primer technology / Chapter 2.8 --- Multiple Tissue Northern (MTN) blot hybridisation / Chapter 2.9 --- RT-PCR analysis of Z313 / Chapter 2.10 --- Subcellular localization study of Z313 by Green Fluorescent Protein (GFP) / Chapter 2.10.1 --- Directional cloning of Z313 into pEGFP-Cl / Chapter 2.10.2 --- Mini-preparation of plasmid DNA / Chapter 2.10.3 --- Transient transfection of plasmids in different cell lines / Chapter 2.10.4 --- Microscope observation of GFP transfected cells / Chapter Chapter 3 --- Results --- p.49 / Chapter 3.1 --- PCR selection of subtracted clones for sequencing analysis / Chapter 3.2 --- Partial sequencing of selected subtracted clones / Chapter 3.3 --- DNA homology searching using program - BLASTN / Chapter 3.4 --- Catalogue of the 467 ESTs from the subtracted normal-counterpart library / Chapter 3.5 --- Classification and frequency of the subtracted normal-counterpart cDNA clones / Chapter 3.6 --- Identification of putative differentially expressed genes in HCC surrounding normal liver / Chapter 3.7 --- Categorization of ESTs exclusively appeared in the subtracted normal- counterpart library / Chapter 3.8 --- In silico structural and functional analysis of zinc finger protein313 (Z313) / Chapter 3.9 --- Molecular cloning of zinc finger protein 313 (Z313) / Chapter 3.10 --- Northern analysis of zinc finger protein 313 (Z313) / Chapter 3.11 --- RT-PCR analysis of zinc finger protein 313 (Z313) / Chapter 3.12 --- Subcellular localization study of zinc finger protein 313 (Z313) / Chapter Chapter 4 --- Discussion --- p.104 / Chapter 4.1 --- EST analysis on the subtracted normal-counterpart cDNA clones / Chapter 4.1.1 --- Characterization of ESTs generated from the subtracted normal-counterpart library / Chapter 4.1.2 --- Putative differentially expressed genes in HCC surrounding normal liver related to hepatocellular carcinoma / Chapter 4.2 --- Molecular cloning and characterization of zinc finger protein313 (Z313) / Chapter 4.3 --- Future aspects / References --- p.121

INTRODUÇÃO: Os vírus das hepatites B (VHB) e C (VHC) são os principais causadores de hepatopatia crônica em todo mundo. Ambos compartilham vias semelhantes de transmissão. Em pacientes portadores crônicos de VHC com sorologia compatível com infecção pregressa pelo VHB (anti-HBcAg[+] e HBsAg [-]), o VHB DNA residual tem sido detectado por técnicas de biologia molecular altamente sensíveis no soro, em células linfomononucleares de sangue periférico e em hepatócitos (como cccDNA), de forma que o anti-HBcAg tem sido associado a pior prognóstico, tanto histológico quanto terapêutico. OBJETIVOS: Analisar a associação entre infecção pregressa pelo VHB nos portadores crônicos do VHC e o dano histológico hepático, além das características epidemiológicas, clínicas e laboratoriais destes pacientes em região de baixa prevalência para o VHB. MÉTODOS: A prevalência do anti-HBcAg foi avaliada em 574 pacientes portadores crônicos de VHC atendidos durante o ano de 2006 no ambulatório de Hepatites Virais do DMIP-HC FMUSP. Deste grupo, foram selecionados 215 pacientes (98 de 112 com anti-HBcAg[+] e 117 de 462 monoinfectados pelo VHC) para análise comparativa. Ainda, 145 indivíduos foram submetidos à análise estatística multivariada, por metodologia de Regressão Logística sequencial, para identificação de possíveis preditores de fibrose avançada. RESULTADOS: Foram avaliados 98 pacientes com marcadores sorológicos de infecção pregressa pelo VHB. Quarenta e seis indivíduos (47%) possuíam o anti-HBcAg de forma isolada. O principal fator de risco relacionado à infecção viral foi hemotransfusão (31,6%). Contudo, a freqüência de UDI foi maior no grupo com infecção pregressa pelo VHB, em relação aos 117 indivíduos monoinfectados pelo VHC (p<0,05). Não houve diferença estatisticamente significativa quanto ao estadiamento (p=0,40) ou à graduação necroinflamatória histológica (APP, p=0,70) entre esses dois grupos. O tempo de infecção e a taxa de progressão de fibrose também foram semelhantes (p=0,99 e p=0,61, respectivamente). A presença do anti-HBcAg não foi considerada preditora de fibrose hepática avançada (p=0,11), porém identificamos como variáveis independentes o tabagismo acentuado (OR 4,40; IC95%: 1,30-14,87), aumento da ALT (OR 1,01; IC95%: 1,00-1,03), de gamagt (OR 1,01; IC95%: 1,00-1,01) e leucopenia (OR 7,75; IC95%: 2,13-28,23). CONCLUSÃO: A prevalência de infecção pregressa pelo VHB em portadores de infecção crônica pelo VHC foi de 20%, sendo este valor compatível com outros estudos realizados em regiões de endemicidade semelhante. A freqüência do marcador anti-HBcAg isolado foi alta neste grupo, refletindo uma possível supressão da imunidade humoral contra o VHB frente a resposta dirigida ao VHC. A infecção pregressa pelo VHB não parece acentuar ou acelerar o dano histológico hepático no nosso meio. / INTRODUCTION: Hepatitis B (HBV) and C (HCV) virus are the main causers of chronic hepatic disease worldwide. Both viruses share similar transmission routes. In chronic HCV infected patients with serological markers of resolved HBV infection (anti-HBcAg [+] and HBsAg [-]), residual HBV-DNA has been detected through highly sensible techniques in serum, PBMC and hepatocytes (as cccDNA). In fact, anti-HBcAg has been associated with worse prognoses, severe histological liver damage and less sustained virological response to HCV treatment. OBJECTIVE: Assess the relationship between previous HBV infection (anti-HBcAg [+]; HBsAg [-]) in patients with chronic hepatitis C (HCV) and histological damage, considering epidemiological, clinical and laboratorial characteristics of this group in a region of low prevalence for HBV. METHODS: Anti-HBcAg prevalence was evaluated in 574 patients seen during a period of one year in a tertiary center (University of Sao Paulo General Hospital, Sao Paulo, Brazil). Of this group, 215 subjects addressed selection criteria and have been selected for evaluation (98 of 112 carriers of anti-HBcAg and 117 of 462 infected only by HCV). 145 individuals have undergone analysis for identification of predictors of advanced fibrosis through univariate and multivariate stepwise logistic regression. RESULTS: Nineteen-eight subjects with serological markers of previous HBV infection were evaluated. Forty-six (47%) patients had anti-HBcAg in isolated form. The main risk factor for infection was blood transfusion (31,6%). However, the IDU frequency was greater in this group (p<0.05). There was no difference regarding histological staging (fibrosis ranging from 0 to 4, p=0.40) or grading (portal inflammation, p=0.70) compared with subjects infected only by HCV with no markers of HBV infection. The rate of fibrosis progression (in units per year) and the infection length was similar in these two groups (p=0,61 and p=0,99, respectively). Anti-HBcAg was not considered a predictor for advanced fibrosis (p=0.11). However, we identified tobacco smoking (OR 4.40; CI 95%: 1.30-14.87), increased ALT (OR 1.01; CI 95%: 1.00-1.03), increased -gt (OR 1.01; CI 95%: 1.00-1.01) and leucopenia (OR 7.75; CI 95%: 2.13-28.23) as independent variables. CONCLUSION: The prevalence of resolved HBV infection in subjects with chronic hepatitis C was 20%. This result was equivalent to other studies carried out in regions of similar endemicity. The frequency of the isolated anti-HBcAg was higher in this group, reflecting a possible suppression of the humoral immunity against HBV caused by an active immune response directed to HCV. Former and resolved HBV infection does not seem to increase or accelerate histological damage in our geographical area.

Os vírus da hepatite B (HBV), C (HCV) e Delta (HDV) causam grande impacto para a saúde pública mundial. Noventa e duas, oito e quatro amostras para HBsAg, anti-HD e anti-HCV, respectivamente, foram identificadas em indivíduos no Maranhão. Cinquenta amostras positivas para HBV DNA foram classificadas em subgenótipo D4 (42/86%) e A1 (8/14%). Para o HDV, apenas quatro foram classificadas como HDV-8. As amostras positivas para anti-HCV não apresentaram RNA detectável. O HBV-D4 parece ser o principal vírus representante na região estudada. O estudo filogenético sugere que houve a introdução de uma única cepa do subgenótipo D4 no Maranhão, enquanto que para o subgenótipo A1 existiu introdução de diferentes cepas. A confirmação do achado do HDV-8 em coinfecção com HBV- D4 suporta a hipótese de origem desses vírus na África. A ausência de infecção ativa pelo HCV é provavelmente devido uma introdução recente desse vírus e/ou menor frequência de meios de transmissão eficientes. Mais estudos são necessários em regiões onde é desconhecido o perfil de infecção desses vírus. / Hepatitis B (HBV), C (HCV) and Delta (HDV) viruses cause a great universal public health concern. Ninety-two, eight and four positive individuals for HBsAg, anti-HD and anti-HCV were identified, respectively. Fifty samples for HBV were classified in. subgenotype D4 (42/86%) and A1 (8/14%). Concerning HDV, four samples were identified as HDV-8 genotype. Anti-HCV positive samples were negative for RNA. HBV-D4 seems to be the main representative in the studied region. The phylogenetic tree topology suggests there was the introduction of a single strain of D4 subgenotype in Maranhao, whereas subgenotype A1 had several introductions of different strains. The finding of HDV-8 in coinfection with HBV D4 confirms the hypothesis of origin of these viruses in Africa. The low number of HCV infection in this region may be due to the recent introduction of this virus and / or lower frequency of efficient means of transmission. More studies are necessary in other regions where the infection profile of these viruses is indefinite.

Hepatitis C is a fast growing infectious disease in Australia and is often associated with related psycho-social and mental health problems. The conventional treatment process for hepatitis C is challenging due to a number of reasons. This study explored social workers’ perceptions of the contribution of their role in hepatitis C treatment centres in relation to the treatment experience of patients. The roles that social workers fulfill, their contribution to the multidisciplinary team and towards a culturally competent service, were explored. Furthermore the knowledge, skills and values required for providing a competent service in a hepatitis C treatment setting was explored. The broad theoretical frameworks that inform social work practice were considered, especially the biopsycho-social model, the strengths perspective, the critically reflexive approach and communications theory. This qualitative study used a semi-structured interview method for data collection. Ten social workers in hepatitis C treatment clinics participated in the study. The findings highlight the needs of patients and how social worker participants described helping to address and meet these needs by employing their knowledge, skills and values through their social work roles and interventions in a team context in a multicultural and multi-faceted work environment. A major challenge that social workers described was to keep patients on treatment despite debilitating side effects that diminish patients' motivation to complete treatment. A shortcoming in the service was described to be the limited psychiatric support available at many treatment centres. The findings lead to a number of recommendations to improve social work services in hepatitis C treatment settings. More research was recommended in areas such as motivational techniques, psychiatric support, and effective group work strategies. The need for increased funding for social work positions in the hepatitis C field was also highlighted. It is anticipated that findings of this study can be applied to hepatitis C treatment in broader settings such as prisons, drug and alcohol settings and general practice. This research will contribute to literature in the field of hepatitis C treatment models and in the field of social work practice in hepatitis C contexts.

Hepatitis C is a fast growing infectious disease in Australia and is often associated with related psycho-social and mental health problems. The conventional treatment process for hepatitis C is challenging due to a number of reasons. This study explored social workers’ perceptions of the contribution of their role in hepatitis C treatment centres in relation to the treatment experience of patients. The roles that social workers fulfill, their contribution to the multidisciplinary team and towards a culturally competent service, were explored. Furthermore the knowledge, skills and values required for providing a competent service in a hepatitis C treatment setting was explored. The broad theoretical frameworks that inform social work practice were considered, especially the biopsycho-social model, the strengths perspective, the critically reflexive approach and communications theory. This qualitative study used a semi-structured interview method for data collection. Ten social workers in hepatitis C treatment clinics participated in the study. The findings highlight the needs of patients and how social worker participants described helping to address and meet these needs by employing their knowledge, skills and values through their social work roles and interventions in a team context in a multicultural and multi-faceted work environment. A major challenge that social workers described was to keep patients on treatment despite debilitating side effects that diminish patients' motivation to complete treatment. A shortcoming in the service was described to be the limited psychiatric support available at many treatment centres. The findings lead to a number of recommendations to improve social work services in hepatitis C treatment settings. More research was recommended in areas such as motivational techniques, psychiatric support, and effective group work strategies. The need for increased funding for social work positions in the hepatitis C field was also highlighted. It is anticipated that findings of this study can be applied to hepatitis C treatment in broader settings such as prisons, drug and alcohol settings and general practice. This research will contribute to literature in the field of hepatitis C treatment models and in the field of social work practice in hepatitis C contexts.

Hepatitis C is a fast growing infectious disease in Australia and is often associated with related psycho-social and mental health problems. The conventional treatment process for hepatitis C is challenging due to a number of reasons. This study explored social workers’ perceptions of the contribution of their role in hepatitis C treatment centres in relation to the treatment experience of patients. The roles that social workers fulfill, their contribution to the multidisciplinary team and towards a culturally competent service, were explored. Furthermore the knowledge, skills and values required for providing a competent service in a hepatitis C treatment setting was explored. The broad theoretical frameworks that inform social work practice were considered, especially the biopsycho-social model, the strengths perspective, the critically reflexive approach and communications theory. This qualitative study used a semi-structured interview method for data collection. Ten social workers in hepatitis C treatment clinics participated in the study. The findings highlight the needs of patients and how social worker participants described helping to address and meet these needs by employing their knowledge, skills and values through their social work roles and interventions in a team context in a multicultural and multi-faceted work environment. A major challenge that social workers described was to keep patients on treatment despite debilitating side effects that diminish patients' motivation to complete treatment. A shortcoming in the service was described to be the limited psychiatric support available at many treatment centres. The findings lead to a number of recommendations to improve social work services in hepatitis C treatment settings. More research was recommended in areas such as motivational techniques, psychiatric support, and effective group work strategies. The need for increased funding for social work positions in the hepatitis C field was also highlighted. It is anticipated that findings of this study can be applied to hepatitis C treatment in broader settings such as prisons, drug and alcohol settings and general practice. This research will contribute to literature in the field of hepatitis C treatment models and in the field of social work practice in hepatitis C contexts.

Diss. (sammanfattning) Stockholm : Karolinska institutet, 2010.

The human hepatitis B virus (HBV) is the prototype member of the Hepadnaviridae family of viruses. Various other hepadnaviruses are used as models to study human HBV infections as all Hepadnaviridae family members have similar virus structure and replication strategies. The studies performed and described in this thesis were carried out using duck hepatitis B virus (DHBV) infection of Pekin ducks as a model system. Hepadnavirus infections can have either an acute or a chronic outcome. The factors that contribute to these outcomes include the immune response, the age of the host at the time of infection as well as size of viral inoculum. The overall aim of this project was to gain a detailed understanding of the mechanisms involved in clearance of virus and resolution of acute DHBV infections. As a first step, molecular and immunohistochemical detection methods for a range of cellular markers in ducks had to be developed as assays were not readily available. Quantitative reverse transcription PCR assays (qRT-PCR) were developed for the detection of mRNA of the duck T-lymphocyte markers, CD3, CD4, CD8, duck cytokines, IFN-α, IFN-γ, TNF-α and the duck housekeeping genes, β-actin and GAPDH. Immunohistochemistry was developed for the detection of duck CD4 + and CD8 + on T cells and for the detection of proliferating cell nuclear antigen (PCNA) as a marker of cell proliferation. These methods were then widely used throughout the project. The innate immune response during HBV infections is not well understood. Toll-like receptors (TLR) are a family of pattern recognition receptors that form part of the innate immune response and are involved in the recognition of bacterial, fungal and viral pathogens. The only TLR that have been reported to recognise viral pathogens are TLR- 2, TLR-3, TLR-4, TLR-7 and TLR-9. The possible role of TLR during hepadnavirus infections had not been well characterized to date. In this project cDNA sequences for duck TLR-2, TLR-4 and TLR-7 were identified and characterised and qRT-PCR assays were developed for their detection. Changes in duck TLR-2, TLR-4 and TLR-7 mRNA expression during hepadnavirus infection were identified following DHBV infection of primary duck hepatocytes (PDH) in vitro. The results showed increased levels of expression of duck TLR early during infection indicating an involvement of TLR and the innate immune response during DHBV infection. During the in vivo DHBV infection studies performed to date TLR mRNA expression remained unchanged. As previously mentioned hepadnavirus infection can have an acute or chronic outcome. We aimed to understand the mechanisms involved during the resolution of acute DHBV infection and to elucidate specific factors contributing to the successful resolution of infection. During acute infections immune markers were monitored by qRT-PCR and histological analysis of fixed liver sections was performed. Liver sections were analysed to detect liver inflammation, the number and size of Kupffer cells, hepatocyte apoptosis and changes in hepatocyte proliferation throughout the course of acute DHBV infection in 6-week-old ducks. By determining the percentage of DHBV-positive hepatocytes two patterns of clearance of acute DHBV infection were observed; early clearance of infected hepatocytes occurring before day 14 post infection (p.i.), and late clearance occurring after day 14, but before or on day 31 p.i. This viral clearance was seen to occur in a cell by cell pattern. Higher levels of hepatocyte proliferation and apoptotic hepatocytes were detected during the clearance phase (on day 14 p.i.) of the late clearance group. Periodic acid schiff-diastase (PAS-D) staining was used to show significant increases in both cell number and size of Kupffer cells. Levels of IFN-γ mRNA increased significantly over the uninfected age-matched control ducks on day 14 p.i. Levels of CD3, CD4 and CD8 mRNA expression also increased over the uninfected controls on days 14 and 31 p.i. In summary, we found that resolution of acute DHBV infection occurred on a cell by cell pattern of clearance, it was accompanied by increases in hepatocyte proliferation, apoptotic hepatocytes and activated Kupffer cells, indicating that T lymphocytes and cell death play important roles in the rapid clearance of DHBV infection. Following resolution of acute hepadnaviral infections residual viral DNA has been found to persist. Residual HBV DNA in humans can result in reactivation of HBV infection following liver transplantation or immunosuppressive drug treatment. This leads to possible pathogenic outcomes thus the need for further investigations. Previous studies performed in the duck model have shown that the major form of residual DNA is present as covalently closed circular DNA (cccDNA). We aimed to understand how this residual cccDNA was being maintained and if replication was involved in the process. Following resolution of infection in ducks, levels of residual DHBV DNA were monitored by quantitative PCR (qPCR). Ducks were treated with the Bristol-Myers Squibb nucleoside analogue Entecavir (ETV) in order to suppress any possible replication that might be maintaining levels of residual cccDNA. In DHBV-infected but non-ETV treated ducks, the levels of residual DHBV DNA decreased gradually when measured on days 60, 221 and 316 p.i. The observed decrease in residual DHBV DNA occurred in parallel with decreases in the rate of hepatocyte proliferation measured by PCNA staining. This finding suggests that levels of residual DHBV DNA and hepatocyte proliferation are linked and we hypothesise that hepatocyte turnover is involved in the clearance of residual DHBV DNA. ETV treatment did not have an effect on the levels of residual DHBV DNA which suggests that it is present in a subset of long-lived hepatocytes that do not support virus replication. Mathematical modelling was performed to predict the rate of hepatocyte proliferation required for the elimination of residual cccDNA. The mathematical modelling showed that the predicted rate of hepatocyte proliferation was consistent with the rate of hepatocyte proliferation measured by PCNA. Further mathematical modelling showed that residual cccDNA is most likely to survive mitosis and it decreases due to several rounds of hepatocyte proliferation required for its elimination. Altogether, this project has elucidated mechanisms involved during the resolution of acute DHBV infection and also possible mechanisms by which residual DHBV DNA is maintained following resolution of infection. Detailed understanding of the virological and immunological events that occur during the resolution of an acute hepadnavirus infection would assist in the development of new therapeutic treatments for the cure of chronic HBV infections. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1345121 / Thesis (Ph.D.) - University of Adelaide, School of Molecular and Biomedical Science, 2008

Hepatitis C is a fast growing infectious disease in Australia and is often associated with related psycho-social and mental health problems. The conventional treatment process for hepatitis C is challenging due to a number of reasons. This study explored social workers’ perceptions of the contribution of their role in hepatitis C treatment centres in relation to the treatment experience of patients. The roles that social workers fulfill, their contribution to the multidisciplinary team and towards a culturally competent service, were explored. Furthermore the knowledge, skills and values required for providing a competent service in a hepatitis C treatment setting was explored. The broad theoretical frameworks that inform social work practice were considered, especially the biopsycho-social model, the strengths perspective, the critically reflexive approach and communications theory. This qualitative study used a semi-structured interview method for data collection. Ten social workers in hepatitis C treatment clinics participated in the study. The findings highlight the needs of patients and how social worker participants described helping to address and meet these needs by employing their knowledge, skills and values through their social work roles and interventions in a team context in a multicultural and multi-faceted work environment. A major challenge that social workers described was to keep patients on treatment despite debilitating side effects that diminish patients' motivation to complete treatment. A shortcoming in the service was described to be the limited psychiatric support available at many treatment centres. The findings lead to a number of recommendations to improve social work services in hepatitis C treatment settings. More research was recommended in areas such as motivational techniques, psychiatric support, and effective group work strategies. The need for increased funding for social work positions in the hepatitis C field was also highlighted. It is anticipated that findings of this study can be applied to hepatitis C treatment in broader settings such as prisons, drug and alcohol settings and general practice. This research will contribute to literature in the field of hepatitis C treatment models and in the field of social work practice in hepatitis C contexts.