Here are some basic terms that are involved in testing (both for those who are finding out their status and those who are HIV positive).

ELISA (Enzyme-linked immunoabsorbent assay): This is the blood test that is done to detect HIV antibodies in order to determine if you have been exposed to HIV. It is an easy and inexpensive test, but is not always 100% accurate. Sometimes it may show positive results for someone who is negative for HIV. Another test, called a Western Blot, is used to verify the results from the ELISA.

gp120: This stands for “glycoprotein 120”. This protein is on the outside of the HIV molecule and is the part that binds to the CD4 receptor on a person’s CD4 cells. This protein is the target for vaccines since it is the first part of the HIV virus that comes in contact with the cell.

p24: This is another protein produced by HIV, but this one is on the inside instead of the outside. Often clinicians will do a p24 test which can also detect an early HIV infection. This is often what is used to test newborns.

PCR (Polymerase Chain Reaction): A test used to detect the levels of virus in the blood

Reverse transcriptase: This is an enzyme produced by HIV that enables it to change its RNA to DNA. Without this enzyme, HIV would not be able to replicate.

RNA: The genetic material for HIV

Surrogate marker: A surrogate marker is any indirect way of measuring a person’s disease progression. For instance, a CD4 cell count is a type of surrogate marker that will indicate how much damage the virus has done to the body but does not necessarily show how much virus is in the blood.

Western Blot: This is another, more specific antibody test. It is usually used to confirm positive results from an ELISA test.