How does the HIV virus affect the immune system?
When a foreign organism enters the body, it is attacked by white blood cells and antibodies in a response coordinated by CD4 lymphocytes (these are a type of white blood cell and are also known as T-cells). When the body is infected with HIV, the HIV virus attaches to the CD4 lymphocytes and enters the cells. Once inside, the virus inserts its own genetic material into the CD4 lymphocytes and then replicates itself. When the new copies of the virus break out of the host cells and enter the bloodstream, they search for other cells to attack. The cycle repeats itself again and again. In the process, more than 10 billion new HIV particles are produced every day. To counter this huge virus production, the immune system turns out as many as 2 billion new CD4 cells daily. Eventually, the virus wins. The number of CD4 cells progressively decreases and the body develops severe immune deficiency whereby it is no longer able to effectively fight off viruses and bacteria that cause disease. AIDS
