Dynamics of acute hepatitis B virus infection in chimpanzees

We formulate a minimum virus infection model aiming at explaining why two acute hepatitis B virus (HBV) infected chimpanzees with low dose HBV DNA inoculation resulted in either prolonged or persistent infections. This model has four variables: number of uninfected cells, number of infected cells, number of free virus (HBV DNA), and number of cytotoxic T lymphocytes (CTL) cells. The equation includes nine parameters. Two of the parameters related to immune reactions will change during the course of the HBV infection. A minimization maximum relative error square criterion is used to determine numerically the two immune parameters. We show that if a basic virus reproductive number is R0(t) < 1, then the virus free solution of the model is globally attractive. This may provide a simple explanation to the observed distinct infection outcomes for two chimpanzees with the same inoculated dosage of 10 GE of HBV DNA. The numerical simulation results also suggest that the immune response plays a key role in clearing the HBV from all infected hepatocytes.