Abstract:
Human Immunodeficiency Virus (HIV) is a retrovirus that badly destroys
the CD4+T cells or T-helper cells in the immune system and becomes the
cause of deadly disease which is called Acquired Immune Deficiency Syn drome (AIDS). After targeting the CD4+T cells of the immune system, HIV
makes multiple copies of itself and hence increase the rate of production of
infected CD4+T cells and free virus cells by decreasing the concentration of
healthy CD4+T cells in blood plasma. Antiretroviral Therapy (ART) is the
most common type of treatment for the control of HIV. It mainly helps to
eradicate the concentration of infected CD4+T cells and viral load in blood
plasma but sometimes healthy CD4+T cells are usually being killed at the
same time. A nonlinear dynamic mathematical model of HIV has been con sidered in this research work. The main objective of this thesis is to design
a controller for antiretroviral drug doses to destroy the maximum number
of infected CD4+T cells and free viruses while increasing the concentration
of healthy CD4+T cells to an adequate level. Cytotoxic T-lymphocytes also
play an active role to destroy infected CD4+T and free viruses with the ef fect of antiretroviral drugs. Four nonlinear controllers namely Backstepping,
integral Backstepping, Lyapunov Redesign and Synergetic controllers have
been designed for this purpose. Lyapunov based stability theory has been
used in these controllers for the analysis of the asymptotic stability of the
system and the convergence of infected CD4+T cells to their desired ref erence value. The simulations of all controllers have been performed using
MATLAB/Simulink.
