Mathematical Biology Seminar Stanca Ciupe Santa Fe Institute "Models of Hepatitis B acute infection" 4:00 p.m., Tuesday, Feb 7, 2006 Mathematical models are developed to test the role of immune responses in various stages of Hepatitis B viral decay in 7 acutely infected patients. Our results show that viral load decline is accompanied by a decrease in infected cells induced by both cytolytic and non-cytolytic mechanisms and many new target cells are generated, with the potential for new infections and renewed viral production. To solve this problem we claim the emergence of a population of cells that are either protected from infection by cytokines, in an internal state of low tolerance for infection or produce virus at extremely low rates.