Here is a list of definitions for the medical terms that you will find in the About HIV section. They are listed in alphabetical order.

Antiretroviral drug - Medication used to treat individuals infected with HIV or other retroviruses. It acts by interfering with viral replication. Zidovudine (AZT, ZDV) and protease inhibitors are examples of antiretroviral drugs.

ELISA - an acronym for Enzyme-Linked Immunosorbant Assay. This is a blood test for antibodies commonly used to detect infection with HIV.

Immune System - A multi-organ system which defends against invading pathogens. The bone marrow, white blood cells (leucocytes), lymph nodes, spleen, thymus and tonsils are all part of the immune system.

Lymphocyte - These are small, round, mononuclear white cells in the blood. There are two main types of lymphocytes, T-cells and B-cells. There two principal types of T-cells, helper T-cells and cytotoxic T-cells. B-cells are responsible for antibody production.

Macrophage - Large mononuclear cells most often found in mucus membranes and the tissues lining the respiratory and digestive tracts where they can engulf and destroy invading pathogens such as viruses and bacteria.

Monoclonal Antibodies - These are molecularly and immunologically homogeneous antibodies, which react solely with a specific antigen such as a blood cell surface receptor.

Monocyte - These are large mononuclear white blood cells that circulate through the blood stream and engulf and destroy foreign matter including microbes.. Monocytes can pass through the linings of the blood vessels into the surrounding tissues. When this occurs, the cells are called macrophages.

Nucleoside Analog - A compound which deceives the viral reverse transcriptase by posing as a fraudulent imitation of the natural nucleosides used for viral replication. The insertion of the fraudulent nucleoside into the viral DNA chain blocks further transcription. Drugs such as AZT, ddC, ddl, and 3TC are all types of nucleoside analogs.

Retrovirus - a virus that has a specific enzyme (reverse transcriptase) that allows it to transcribe its RNA genome into a DNA copy, the reverse of the usual process in nature.

Reverse Transcriptase - an enzyme that allows HIV and other retroviruses, to copy their RNA sequences into DNA for incorporation into the cell genome.

Serologic Testing - A blood test that detects serum antibodies to specific pathogens. such as HIV.

Perinatal Antiretroviral Treatment - Perinatal refers to the time shortly before or after the birth of a baby. This term refers to antiretroviral treatment of HIV+ mothers and/or their infants during this period in order to reduce the risk of viral transmission from mother to baby.

Polymerase - an enzyme that catalyses the linkage of nucleotides into the long-chain molecules of DNA or RNA which make up the genomes of all living things.

Western Blot - a highly specific method of testing for HIV antibody in the blood. It is commonly used to confirm results of ELISA testing.