English abstract
M. A. Nowak and C. R. M. Bangham, 1996 developed three ordinary differential equations
models for infection dynamics. The model which we studied consists of four variables i.e.
uninfected cells, infected cells, free virus particles and virus specific CTLs. We discussed the
stability of the equilibrium points to predict long time behaviour of the system. We proved
that global stability of the equilibria having only uninfected cell and for other equilibria we
investigated conditions under which equilibrium points will be asymptotically stable. Then we
introduced time delay in the model and studied conditions under which steady states will be
asymptotically stable. We examined that for endemically infected equilibrium a critical value
of time delay may occur. The steady state may be asymptotically stable when delay will be less
than critical value and when delay passes through critical value then uninfected cells, infected
cells, free virus and CTLs may undergo cyclic oscillations.
