After HIV enters your body, it begins to reproduce itself. This is known as the HIV life cycle. HIV searches for a type of white blood cell known as a T-Cell (also known as a CD4 cell). These cells are an important part of the immune system - they activate to fight diseases in the body.

When HIV finds one of these T-cells, it attaches and then injects its own genetic material into the cell. Inside the T-Cell, the virus makes copies of itself. These copies then exit the cell and go on to repeat the process in other T-Cells in the body. These T-cells are like security guards. When they are strong, they can fight off infection - but when HIV enters the cell, it causes damage and will eventually kill the cell. As HIV infection grows in the body over time, it eventually will overpower the T-cells and the immune system is no longer able to fight off infections. At this stage, PLHIV without treatment will start to get ill.