Control of HIV virus using Nonlinear Control Techniques

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.