الفهرس 
Introduction and aim of the workOnly 14 pages are availabe for public view
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Abstract
HCV, a blood-borne enveloped RNA-containing member of the Flaviviridae family, causes both acute and chronic hepatitis which is a major worldwide cause of chronic liver disease, cirrhosis, hepatocellular carcinoma and death from end-stage liver disease. This RNA virus is characterized its propensity to persist in approximately 70% of infected hosts. Egypt has the highest HCV prevalence worldwide and the use of parenteral antischistosomal therapy has been implicated in the high rate of infectionand The most prevalent genotypein Egypt is HCV 4a . Currently, antiviral therapy for HCV consists of treating the patient with interferon (IFN)-α and ribavirin. However, this treatment is far from being ideal; it is associated with significant side effects, is expensive, and is only effective in 50–60% of cases Unfortunately, there is currently no available vaccine to protect individuals against HCV and block its progression. ultimately the goal of HCV research is the development of an effective vaccine. This, however, would require more extensive knowledge of the anti-HCV immune response. Studies of this response have been impaired by several difficulties. The first is that acute HCV infections are often asymptomatic, and it is therefore difficult to follow the evolution of the disease before it becomes chronic. Second, most HCV studies have based their conclusions on analysis of HCV-specific immune responses in peripheral blood, which might not be representative of the anti-HCV response in the liver and secondary lymphoid organs and are hampered by issues of sensitivity. Finally, study on HCV is limited by the lack of a small animal model: the chimpanzee is the only animal model currently available. Although the disease induced by HCV in chimpanzees is milder than in humans and is cleared in a higher proportion of subjects, this experimental model has provided essential insights into the immune response to HCV that have subsequently been confirmed in humans Some of these insights include the critical role of the cellular immune response in viral clearance, and the striking several weeks’ delay in generating both detectable CD4+ and CD8+ T cell HCV-specific responses following infection. Understanding these phenomena is essential for the development of an effective HCV vaccine But as regard the B lymphocytic responses during HCV infection the anti HCV antibodies does not seem to be protective against HCV infection.