Avidan U Neumann

The viral kinetics of Hepatitis C virus (HCV) during treatment with IFN is very different of that of HIV during current anti-retroviral treatment. HIV shows a viral decline with a half-life of about 1-2 days after a delay of 1-2 days. In contrast, for HCV a more rapid, dose-dependent, decline occurs already at 6-10 hours after the first injections, followed by a slower 2nd phase decline comparable in some patients to that of HIV. Furthermore, in HIV the decline slope between days 1-7 slows during the first month of treatment, while for HCV this further slowing down is not observed. Modeling of the HCV kinetics shows that the difference is due to different mechanisms of anti-viral effect, blocking infection for HIV while blocking production for HCV. The HCV models allow to directly estimate parameters that can not be estimated from HIV kinetics, such as the absolute effectiveness of the drug and the clearance rate of free virus. In addition, the early kinetics of HCV decline has a better predictive value for the success of treatment than HIV and can be used to make clinical decisions. Thus, allowing us to introduce individualized treatment approaches based on viral dynamics.