Hepatitis C virus (HCV) is an enveloped, positive-sense single-stranded RNA virus and a member of the family Flaviviridae. The virus primarily resides in the liver and causes an immune response which leads to inflammation. Over time, prolonged inflammation may cause scarring eventually leading to liver cirrhosis. When the liver becomes cirrhotic, it fails to perform its normal functions, (liver failure), and this leads to serious complications and even death. Upon infection the positive sense single-stranded RNA is translated to produce a single protein product, which is then further processed to produce smaller active proteins. Translation of the HCV genome yields ten proteins, by which the first one is Core and, essential for the production of the viral capsid. The observed effects of the Core protein include the induction of liver cancer, transformation of cells, and alterations of immune responses. During the translation of Core, Alternative Reading Frame Products (ARFP) also known as F-proteins, can be produced. These proteins, which are highly uncharacterized, are dependent on variable ribosomal frame shifting during the translation of the Core region just downstream the internal Ribosome Entry site (IRES) of the viral genome. Due to the absence of the 5'cap recognition sequence, which is required for the assembly of the initiation complex, translation is dependent on the IRES instead, a nucleotide sequence stretch within the 5'UTR region. Most studies seek to define cryptic functions of the Core protein and they have acknowledged that these ARF products may affect the production and function of Core. The goal of this project is to develop a cell-based assay that monitors ribosomal frameshifting within the Core protein region of the HCV genome. The assay was used to elucidate what may influence the occurrence of these shifts leading to the production of the different ARFs and, alternatively, how ARFs may influence frameshifting.