Not to be confused with group presentation. Representation theory is a branch of mathematics that studies abstract algebraic structures by representing their elements as linear transformations of vector spaces, and studies modules over these abstract algebraic structures.
The signature effect of HIV infection, and the cause of AIDS, is disruption of the T-lymphocyte branch of the immune system and in particular the destruction of CD4+ T-helper cells.
All viruses must infect living cells to reproduce. HIV takes over certain immune system cells that are supposed to defend the body. These cells are called CD4 cells, or T cells. When HIV takes over a CD4 cell, it turns the cell into a virus factory. It forces the cell to produce thousands of copies of the virus.