The human immunodeficiency virus (HIV) changes (mutates) often. Sometimes these changes make the virus resistant to a particular medicine or class of medicines, which means the medicine is no longer effective against the virus. When this happens, the medicine no longer controls virus growth (replication) or protects the immune system.
Resistance testing is done to determine whether resistance has caused treatment to fail and to identify antiretroviral medicines that can be used to treat the infection. There are many reasons that treatment fails, such as:
AIDS (acquired immune deficiency syndrome) isn't a disease in itself; rather, AIDS is a condition that develops when a person's body has been weakened by HIV (the human immunodeficiency virus). HIV is found in blood and sexual fluids and spreads mainly through unprotected sexual contact and the sharing of hypodermic needles and equipment.
When a person becomes infected with HIV, it damages his or her immune system, leading to immunodeficiency; the immune system can no longer fight off common germs...