modeling virus dynamics Our work:stability,bifurcations(within-host level)Purpose is to understand the conditions to control or eliminate infections.I nteractions of suscepti ble cel Is，i n fected ce I I s，viruses andimmunecells .With the aid of Mactone package Matcont，we find asubcritical Hopf bifurcation，Therefore，the dynamics of populationscan evolve to a stable periodic solution，or tend tothe stable positive equilibrium，depending upon initial values.