Complete classification of global dynamics of a virus model withimmune responses

A virus dynamics model for HIV or HBV is studied, whichincorporates saturation effects of immune responses and anintracellular time delay. With the aid of persistence theory andLiapunov method, it is shown that the global stability of the modelis totally determined by the reproductive numbers for viralinfection, for CTL immune response, for antibody immune response,for antibody invasion and for CTL immune invasion. The resultspreclude the complicated behaviors such as the backward bifurcationsand Hopf bifurcations which may be induced by saturation factors anda time delay.