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Development of an intra- and intergenotypic HCV cell culture method to phenotype and assess antiviral susceptibilities and resistance development of HCV NS3 protease genes from HCV genotypes 1-6Imhof, Ingrid January 2010 (has links)
The development of specific antiviral drugs directly targeting the hepatitis C virus (HCV) is clinically important, as the current standard interferon/ribavirin combination treatment is only partially effective, expensive and often associated with severe side effects. Inhibitors of the NS3 protease (PI) therefore represent a promising alternative or additional therapy. To date, the development and in vitro evaluation of PIs is restricted to the genotype 1/2 based replicon and the genotype 2a full length viral cell culture system. However, proteases of the different HCV genotypes vary substantially in their amino acid sequence and secondary structure and require separate evaluation of their efficacy before they go into clinical trials. To address this issue, a panel of intra- and intergenotypic recombinants based on the recombinant infectious clone Jc1 (pFK JFH1/J6/C-846) was developed in this work. The viability of these recombinants was assessed in the Huh7.5 cell culture system, where replicating viruses were detected by HCV-NS5A immunostaining. Intergenotypic recombinants containing genotype 1a, 1b, 3a, 4a and 6a derived proteases were replication defective, whereas the recombinant with genotype 5a derived protease replicated efficiently after acquiring cell culture adaptive mutations. The replacement of not only the NS3 protease gene region, but also its cofactor NS4A, allowed the generation of replication competent intra- and intergenotypic recombinants for all 6 major genotypes. Replacing the NS3 protease of the recombinants with that of patientderived proteases also generated replicating recombinants, greatly expanding the panel of intergenotypic recombinants available for phenotyping and PI evaluation. However, intra- and intergenotypic recombinants showed substantial differences in their replication kinetics, which may be influenced by naturally occurring polymorphism between genotypes and the differential requirement of adaptive/attenuating cell culture mutations. Genotype 1a recombinants replicated very poorly, which may be due to incompatibilities between the type 1a NS3/4A protease and the type 2a backbone. 50% inhibitory concentrations (IC50) of different PIs were measured using Foci Forming Units/ml (FFU/ml) reductions and replication inhibition assays. The different recombinants showed consistent, genotype-associated differences in their susceptibility to the PI BILN 2061, with genotypes 2a, 3a and 5a derived recombinants showing approximately 100-fold lower susceptibility than genotype 1b, 4a and 6a derived recombinants. These observations are consistent with major differences in response rates found in recent treatment trials of genotype 1, 2 and 3 infected patients. Differences in susceptibility were also observed for VX-950, with genotype 1b, 2a and 6a derived recombinants being twice as susceptible than genotype 3a, 4a and 5a derived recombinants. Passaging the intra- and intergenotypic recombinants under increasing concentrations of PI allowed the identification of PI resistance mutations. Resistance mutations to BILN 2061 mapped to the previously identified positions 156 and 168 within the NS3 protease, with a great diversity of amino acid substitutions observed within each genotype. Reintroduction of the identified resistance mutations into the original recombinant viruses conferred increased resistance towards BILN 2061 and some mutations also affected replication kinetics of the recombinants. The developed system will be of major value for the phenotypic characterisation of naturally occurring and treatment induced resistance mutations within all 6 major HCV genotypes towards different PIs. This will allow treatment response predictions for newly developed PIs before they enter clinical trials and the development of individually tailored antiviral treatment regimes.
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Study on Hepatitis C virus (HCV) subtypes in Sweden before and after the universal screening of blood donorsKhalil, Yasmin January 2010 (has links)
<p>Since the discovery in 1989 of hepatitis C virus (HCV) as the infectious agent responsible for the vast majority of post-transfusion non-A non-B hepatitis, blood transfusions are no longer a source for HCV transmission in Sweden. Anti-HCV testing was implemented for all blood donations in 1992. Since then intravenous drug use (IDU) has become the major route of transmission in the western world. Six genotypes and more than 80 subtypes of HCV have now been identified world-wide. These genotypes and subtypes are determined by genetic divergences between the HCV strains. Subtypes 1a, 1b, 2b, 2c, and 3a have global spread, while the other subtypes have a more limited geographical distribution. Little was known on the prevalence of HCV among blood donors and on which genotypes and subtypes of HCV were circulating in Sweden before the testing of all blood donations was implemented. The prevalence of anti-HCV was therefore investigated in sera sent to the Swedish Institute for Infectious Disease Control (SMI) from 412 patients; 241 were sampled between 1970 and 1991 before the universal screening in 1992, while 171 were sampled between 1992 and 2002. The samples derived from 193 (47%) blood donors, (104 sampled before, and 89 after 1992), and from seven other groups of patients. Two groups had suspected known routes of infection, intravenous drug use (IDU) 33 patients and hemodialysis, 16 patients, while it was unknown for the other patients. Anti-HCV was detected in 120 (29%) samples. The highest frequency was found among IDUs, (91%). Before general screening was implemented, 2.8% of the blood donors were positive for hepatitis C, whereas 28% of those sampled after 1992 were anti-HCV positive. Those latter samples were sent to SMI due to anti-HCV reactivity in a primary test at the blood centre. HCV RNA could be detected by PCR in 56 (47%) of the anti-HCV positive samples, the subtype could be determined by sequencing in 45 (80%) of those. The subtypes found were 1a in 31 %, 1b in 18%, 2b in 22%, and 3a in 27%. One sample was of subtype 2c. There was a tendency of increase of genotype 2 and a decrease in subtype 1a with time. 1a was found in 38% of the samples collected before 1992, while it was only found in 19% of the samples from 1992 or later. On the other hand genotype 2 was found in 17% sera sampled before 1992 and in 37% of the samples collected 1992 or later. It is not known if this genotype has recently been introduced into Sweden. Further analysis on larger series of samples is needed to confirm these preliminary results.</p> / AcknowledgmentsI would like to express my gratitude to several people who have been supportive in different ways throughout this project.First of all, I want to thank my supervisor Helene Norder, for giving me the possibility to do my diploma thesis at the Department of Virology, Swedish Institute for Infectious Disease control (SMI) and for helping me during this study and for the many insightful conversations during the design and development stages of the application, and also for the many helpful comments and suggestions on the text of the thesis.I want to express my appreciation to my laboratory supervisor Regina Wallin, Camilla Jern and Josefine Ederth for helping me during the procedure for this study. Then, I want to thank my examiner Magnus Johansson from the Södertörns university collegefor his advice on writing this paper. Finally, I would like to thank my family and specially my mother Bahar Hamid for always supporting me during my whole life.Last, but not least, I would like to thank my friends Annika Andersson and Yourdons Yemane for being encouraging, understanding and always supportive.
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Recontextualising the lived experience of hepatitis C and its treatmentWhiteley, David James January 2016 (has links)
BACKGROUND: Rapid advances in the treatment of the hepatitis C virus (HCV) have been witnessed in clinical practice over the last five years. Pharmacological developments have ended the reliance on the drug interferon-α as a component of successful therapy, heralding the dawn of a new era in the fight against the disease. How this new era is being understood and experienced by those individuals living with the virus is currently unknown. METHODS: A purposive sample of 20 individuals participated in face-to-face semi-structured interviews exploring their experience of living with HCV. Eight of these participants were interviewed again following a period of interferon-free treatment. All interviews were conducted between June 2015 and March 2016. The interviews were transcribed verbatim and explored using thematic analysis, underpinned by social phenomenological theory. RESULTS: Analysis of the corpus of data resulted in three overarching themes entitled ‘positioning HCV', ‘beyond a physical burden' and ‘reconstructing uncertainty'. These themes offer original insight into how this new era of therapy is being realised by those living with the virus. The experience of interferon-free treatment was also explored through the narratives of those individuals who participated in a further post-treatment interview. Three further themes entitled ‘expectations and realisations', ‘an honour and a pleasure' and ‘treatment needs' encapsulate their experience. DISCUSSION: The findings from this study recontextualise the lived experience of HCV within a new era of treatment. In doing so, they expose social and emotional spheres of illness, and a perception of illness chronicity, which remain untouched by the treatment revolution. Further, this work emphasises how treatment inequalities fundamentally underpin multiple aspects of the daily lived experience, and are integral to how those living with HCV articulate the disease. The implications of this work challenge current HCV policy and clinical practice.
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Study on Hepatitis C virus (HCV) subtypes in Sweden before and after the universal screening of blood donorsKhalil, Yasmin January 2010 (has links)
Since the discovery in 1989 of hepatitis C virus (HCV) as the infectious agent responsible for the vast majority of post-transfusion non-A non-B hepatitis, blood transfusions are no longer a source for HCV transmission in Sweden. Anti-HCV testing was implemented for all blood donations in 1992. Since then intravenous drug use (IDU) has become the major route of transmission in the western world. Six genotypes and more than 80 subtypes of HCV have now been identified world-wide. These genotypes and subtypes are determined by genetic divergences between the HCV strains. Subtypes 1a, 1b, 2b, 2c, and 3a have global spread, while the other subtypes have a more limited geographical distribution. Little was known on the prevalence of HCV among blood donors and on which genotypes and subtypes of HCV were circulating in Sweden before the testing of all blood donations was implemented. The prevalence of anti-HCV was therefore investigated in sera sent to the Swedish Institute for Infectious Disease Control (SMI) from 412 patients; 241 were sampled between 1970 and 1991 before the universal screening in 1992, while 171 were sampled between 1992 and 2002. The samples derived from 193 (47%) blood donors, (104 sampled before, and 89 after 1992), and from seven other groups of patients. Two groups had suspected known routes of infection, intravenous drug use (IDU) 33 patients and hemodialysis, 16 patients, while it was unknown for the other patients. Anti-HCV was detected in 120 (29%) samples. The highest frequency was found among IDUs, (91%). Before general screening was implemented, 2.8% of the blood donors were positive for hepatitis C, whereas 28% of those sampled after 1992 were anti-HCV positive. Those latter samples were sent to SMI due to anti-HCV reactivity in a primary test at the blood centre. HCV RNA could be detected by PCR in 56 (47%) of the anti-HCV positive samples, the subtype could be determined by sequencing in 45 (80%) of those. The subtypes found were 1a in 31 %, 1b in 18%, 2b in 22%, and 3a in 27%. One sample was of subtype 2c. There was a tendency of increase of genotype 2 and a decrease in subtype 1a with time. 1a was found in 38% of the samples collected before 1992, while it was only found in 19% of the samples from 1992 or later. On the other hand genotype 2 was found in 17% sera sampled before 1992 and in 37% of the samples collected 1992 or later. It is not known if this genotype has recently been introduced into Sweden. Further analysis on larger series of samples is needed to confirm these preliminary results. / AcknowledgmentsI would like to express my gratitude to several people who have been supportive in different ways throughout this project.First of all, I want to thank my supervisor Helene Norder, for giving me the possibility to do my diploma thesis at the Department of Virology, Swedish Institute for Infectious Disease control (SMI) and for helping me during this study and for the many insightful conversations during the design and development stages of the application, and also for the many helpful comments and suggestions on the text of the thesis.I want to express my appreciation to my laboratory supervisor Regina Wallin, Camilla Jern and Josefine Ederth for helping me during the procedure for this study. Then, I want to thank my examiner Magnus Johansson from the Södertörns university collegefor his advice on writing this paper. Finally, I would like to thank my family and specially my mother Bahar Hamid for always supporting me during my whole life.Last, but not least, I would like to thank my friends Annika Andersson and Yourdons Yemane for being encouraging, understanding and always supportive.
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Structural studies on a hepatitis C virus-related immunological complex and on Ebola virus polymerase cofactor VP35Fadda, Valeria January 2015 (has links)
Hepatitis C virus (HCV) is one of the leading causes of hepatocellular carcinoma worldwide. HCV-neutralizing antibody AP33 recognizes a linear, highly conserved epitope on the viral entry protein E2, disrupting the interaction with the cellular receptor CD81 that leads to viral entry. AP33-related anti-idiotypes (Ab₂s) have the potential to carry the internal image of the antigen E2, eliciting the production of AP33-like antibodies in humans. This study reports the mid-resolution structure of the Fab fragment of anti-idiotype A164.3 and the high-resolution structure of the Fab fragment of AP33 in complex with the Fv fragment of anti-idiotype B2.1A. Analysis of the structures and comparison with the previously published structure of AP33 in complex with a peptide corresponding to the E2 epitope, suggests that while A164.3 does not mimic the antigen E2, B2.1A is characterized by high surface complementarity with AP33 and functional antigen mimicry. Thus, B2.1A can be classified as an Ab₂-β, a subgroup of anti-idiotypes carrying the internal image of the antigen. Preliminary binding studies show that AP33 binds B2.1A with nanomolar affinity, supporting the role of B2.1A as an idiotypic vaccine candidate. Zaire ebola virus causes severe, often lethal hemorrhagic fever in humans. Ebola virus polymerase cofactor VP35 is a multifunctional protein involved in, among other functions, dsRNA binding and inhibition of the host's interferon pathways. VP35 contains an N-terminal oligomerization domain and a C-terminal dsRNA-binding domain (RBD). Preliminary results on the oligomerization domain of VP35 suggest that this region contains a coiled-coil motif, as previously reported. In order to validate a recently-discovered dsRNA end-capping pocket as a drug target, the structure of VP35 RBD I278A mutant was solved at high resolution, showing that even a small perturbation in the binding pocket can cause dramatic binding impairment due to loss of contacts with dsRNA.
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Investigation on the risk of viral infection in musculoskeletal graftsYao, Felix Caspar January 2010 (has links)
[Truncated abstract] Around 50,000 hip and knee replacements are performed every year in Australia and this number has been increasing by around 13% annually since 1998 (Transplantation Society 2006). The incidence and number of revision surgery has increased by a similar proportion. Autogenous bone or allograft is still the gold standard grafting material and is currently used in a variety of reconstructive surgical procedures. The use of any allograft material carries with it the risk of transfer of disease from donor to recipient. These tissues can transmit the same viral and bacterial infections as blood, and the products of a single donation may be transplanted to several recipients. In contrast to blood, musculoskeletal tissues may come from surgical and cadaveric donation. Overall, the prevention of infection relies on the maintenance of rigid protocols for procurement, donor and allograft testing, secondary sterilisation, and the adherence to internal safety standards within the tissue banks. This thesis aims to determine the risk of viral infection among musculoskeletal tissue donors in Australia. We retrieved and analysed data retrospectively from three large tissue banks in Australia (Perth, Queensland, Victoria). This includes 12,415 musculoskeletal tissue donors, 10,937 of which are surgical donors and 1,478 of which are deceased donors, for the period of 1993 -2004. This data was analysed to determine the prevalence and incidence of viral infections such as human immunodeficiency virus (HIV), hepatitis B virus (HBV), hepatitis C virus (HCV) and human T-lymphotropic virus (HTLV) in musculoskeletal allografts. The results indicate that the risk of viral infection from musculoskeletal tissue transplantation in Australia is low. ... The results indicate that the overall prevalence of screened transfusion-transmitted viral infections did not vary significantly for musculoskeletal donors over the study period, despite falling in the general population and first-time blood donors. In tissue donors, HIV incidence significantly decreased over time, and HBV decreased significantly during 1999-2001; however, there was an apparent increase in the estimated incidence of HCV in 2002-2004 compared with earlier years. Furthermore the residual risk estimate of HIV in the period 2002-2004 has declined 5-fold compared to estimates in the period 1993-1995. This is perhaps due to greater awareness of high risk behaviours among donors, improvement in donor recruitment and an overall decrease in infection levels in the general population. Musculoskeletal tissue is second only to blood as the most frequent transplanted human tissue. Viral infection is a potential complication of tissue transplantation. In this thesis the rates of HIV, HBV, HCV and HTV infection in musculoskeletal donors in Australia were identified and then compared with results in published data from Canada, Scotland and the United States. The study also compared that result with first-time blood donors because they have satisfied similar donor selection criteria (Galea et al. 2006). The results indicate that prevalence and incidence estimates for viral infection in Australian tissue donors are higher than those in blood donors. This was also reported in studies from other countries. Accordingly, it is crucial that viral prevalence and incidence be monitored to evaluate the safety of tissue supply and to improve donor selection processes.
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