HIV, also referred to as the human immunodeficiency virus, infects and destroys the immune system cells, making it difficult to fight off other diseases. When HIV has significantly compromised your immune system, it can lead to acquired immunodeficiency syndrome (AIDS).AIDS is the last and most critical stage of an HIV infection. Individuals suffering from AIDS have very low counts of certain white blood cells and severely compromised immune systems. They may have additional illnesses that indicate the development of AIDS. Without therapy, HIV infections progress to AIDS in about 10 years.