<qa>  What is the effect of HCV co-infection on HIV and HCV?An estimated 50,000 people in Puerto Rico are infected with HCV. HIV and HCV have similar routes of transmission, and HCV co-infection occurs in 8 to 23 of HIV infected patients. Researchers have shown that treatment for HCV with Rebetron ribavirin plus interferon alfa-2b significantly decreases HCV viral load without affecting HIV viral load. However, measurements of intracellular levels of the active forms of zidovudine ZDV-MP and ZDV-TP were not performed. Such measurements are needed to provide a more rational basis for dosing in HIVHCV co-infected patients. This study will investigate the intracellular exposure to active ZDV metabolites prior to and after treatment with Rebetron or treatment with PEG-Intron pegylated interferon and ribavirin. 