Biomathmatics&Bioengineering: the art of mathematical modelling: HIV/AIDS modeling

Introduction

Acquired immunodeficiency syndrome (AIDS) is medically devastating to its victims, and wreaks financial and emotional havoc on everyone, infected or not.

Keywords: Viral Replication; Immunology.

“Viruses are very small biological structures whose reproduction requires a host cell.” They are not considered living things.

Helper T-lymphocytes play a key role in the process of gaining immunity to specific pathogens HIV is an especially versatile virus. It not only inserts its genetic information into its host’s chromosomes, but it then causes the host to produce new HIV. A virus cannot reproduce outside a host cell, which must provide viral building materials and energy.

The immune system monitors the body for dangerous pathogens. When it detects pathogens, the immune system computers and mobilizes the appropriate responses. The immune system is made of a vast collection of cells that communicate and interact in myriad ways. One of the major tools of the immune system is antibodies. One of the important roles of the immune system is to scan the cells of the body for antigens – foreign proteins made by pathogens –. The scanning process is carried out by T-cells.

Viral nucleic acid enters the host cell and redirects the host cell’s metabolic apparatus to make new viruses.

“Many RNA viruses do not use DNA in any part of their life cycle.”

Modeling

Key-point 1 : To find an optimal chemotherapy strategy in the treatment of the human immunodeficiency virus (HIV).

Key-point 2: The model used herein describes the interaction of the immune system with HIV.

Key-point 3: It is assumed the treatment acts to reduce the infectivity of the virus for a finite time.

Antiretroviral drugs are medications for the treatment of infection by retroviruses, primarily HIV.

Different classes of antiretroviral drugs act on different stages of the HIV life cycle. Combination of several (typically three or four) antiretroviral drugs is known as highly active anti-retroviral therapy (HAART). One of the biggest challenge nowadays, from a mathematical standpoint is how to make models that account for drug interactions, giving happens, but is neglected in general for simplicity sake.

Each T cell attacks a foreign substance which it identifies with its receptor. T cells have receptors which are generated by randomly shuffling gene segments. Each T cell attacks a different antigen. T cells that attack the body's own proteins are eliminated in the thymus. Thymic epithelial cells express major proteins from elsewhere in the body.

First, T cells undergo "Positive Selection" whereby the cell comes in contact with self-MHC expressed by thymic epithelial cells; those with no interaction are destroyed. Second, the T cell undergoes "Negative Selection" by interacting with thymic dendritic cell whereby T cells with high affinity interaction are eliminated through apoptosis (to avoid autoimmunity), and those with intermediate affinity survive. A related theory is called kinetic proofreading, developed by J Hopfield.