Browsing Ph.D. Biology by Title
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STRATEGIES FOR PREVENTION AND TREATMENT OF HEPATITIS C VIRUS INFECTIONHepatitis C virus (HCV) is the causative agent of Hepatitis C, a serious global health problem which results in liver cirrhosis and hepatocellular carcinoma. Currently there is no effective treatment or vaccine against the virus. Therefore, development of a therapeutic vaccine is of paramount importance. In this project, three alternative approaches were used to control HCV including a DNA vaccine, a recombinant viral vaccine and RNA interference. The first approach was to test the effect of different promoters on the efficacy of a DNA vaccine against HCV. Plasmids encoding HCV-NS3 and E1 antigens were designed under three different promoters, adenoviral E1A, MLP, and CMV ie. The promoter effect on the antigen expression in 293 cells, as well as on the antibody level in immunized BALB/c mice, was evaluated. The results showed that the antigens were successfully expressed from all vectors. The CMV ie promoter induced the highest antigen expression and the highest antibody level. Second, the efficiency of a recombinant adenovirus vaccine encoding HCV-NS3 was compared to that of a HCV-NS3 plasmid vaccine. The results showed that the recombinant adenovirus vaccine induced higher antibody levels as compared to the plasmid vaccine. The relationship between the immune response and miRNA was also evaluated. The levels of mir-181, mir-155, mir-21 and mir-296 were quantified in the sera of immunized animals. mir-181 and mir-21 were found to be upregulated in animals injected with adenoviral vectors. Third, two recombinant adenoviruses encoding siRNAs targeting both the helicase and protease parts of the NS3 region were tested for their ability to inhibit NS3 expression. The results showed that the siRNA against protease was more effective in silencing the HCV-NS3 gene in a HCV replicon cell line. This result confirmed the efficiency of adenovirus for siRNA delivery. These results confirmed that CMV ie is optimum promoter for immune response induction. Adenovirus was shown to be an effective delivery vector for antigens or siRNAs. In addition, miRNAs were proved to be involved in the regulation of immune response.
Thermal tasting: methodological considerations and implications for alcohol behaviour.Thermal tasting is a phenomenon whereby some individuals perceive thermally-induced taste sensations when their tongue is warmed or cooled. These individuals, known as thermal tasters (TT), report a variety of thermally-induced tastes and the tastes reported can vary with temperature regime used and location on the tongue tested. TT are typically compared to thermal non-tasters (TnT), individuals who do not experience thermally-induced sensations. The literature suggests that TT give higher intensity ratings to orosensory stimuli than TnT; however, small sample sizes and differences in classification schemes between studies confound our understanding of TTS (thermal taste status). It is unknown whether the increased orosensory responsiveness of TT is universal or whether it is driven by a subgroup of TT. Furthermore, up to 50% of individuals are non-classifiable (NC). The largest database of individuals who have undergone TTS screening was compiled to address the literature gaps. Findings indicate that TT are more responsive than TnT to orosensory stimuli, regardless of the classification scheme used. The orosensory responsiveness of NC is not homogeneous, suggesting that NC are not a separate group but rather misclassified TT and TnT. Sweet TT are more likely than non-sweet TT to experience thermally-induced sensations during lingual warming. Similarly, sour TT are more likely than non-sour TT to report thermally-induced tastes during cooling. However, no differences in orosensory responsiveness based on these or other subgroups are identified, suggesting that the heightened orosensory responsiveness of TT is universal across this phenotype. The final study sought to characterize the binary interactions between ethanol and four orosensory stimuli (fructose, quinine, tartaric acid and alum sulphate) both overall and by comparing TT and TnT. In general, TT are more responsive than TnT to all stimuli in the study. Few interactions between TTS and stimulus intensity exist suggesting that TT and TnT perceive the sensations elicited by alcoholic beverages similarly, albeit at different intensities. Together, the thesis helps inform best practices for TTS screening and classification, provides insights into TTS mechanisms and furthers our understanding of alcoholic beverage perception.