HIV/AIDS Glossary
compiled by Jeff Berry
Acquired Immunodeficiency Syndrome (AIDS): the late stage of the condition triggered by infection with HIV. According to the official definition by the Centers for Disease Control (CDC), a person receives an AIDS diagnosis when he or she has a CD4 cell count of less than 200 and/or certain opportunistic infections common with advanced immune deficiency.
Acute HIV Infection: the first few months after HIV infection. This initial infection precedes seroconversion and is sometimes characterized by fever, sore throat, headache, skin rash and swollen glands. Also called Primary Infection. Adherence: the degree to which a patient sticks to a schedule for taking medicines. Non-adherence may lead to drug resistance. Also called “compliance.”
AIDS Drug Assistance Program (ADAP): ADAPs serve people with HIV/AIDS who are uninsured or underinsured, including those who are not disabled and, therefore, ineligible for programs like Medicaid. ADAPs are authorized by the Ryan White Care Act. Federal funding goes to states, which use a portion of the money to provide HIV/AIDS drugs, including prophylaxis and treatment of opportunistic conditions, to those who cannot otherwise afford the medications.
Antibody: a disease-fighting protein created by the immune system, also known as immunoglobulin. Antibodies coat, mark for immune destruction, or render harmless foreign matter such as bacteria, viruses or dangerous toxins. Antibodies also tag virus-infected cells, making them vulnerable to attack by the immune system.
Antigen: a foreign substance, usually a protein, that stimulates an immune response. An antigen may have several subunits called epitopes that are targets of specific antibodies or cytotoxic T lymphocytes.
Antiretroviral (ARV): a substance that stops or suppresses the activity of a retrovirus, such as HIV. Nucleoside analogs and protease inhibitors are examples of antiretroviral drugs
Asymptomatic: without signs or symptoms of disease or illness.
B Cell (B Lymphocyte): a type of lymphocyte that is a precursor to plasma cells. During infections, individual B cell clones multiply and are transformed into plasma cells, which produce large amounts of antibodies against a particular antigen on a foreign microbe. This transformation mainly occurs through interaction with the appropriate CD4 cells. BID: abbreviation for bis in die, a Latin phrase meaning “twice a day.” A drug prescribed this way should be taken every twelve hours.
Bioavailability: the extent to which an oral medication is absorbed in the digestive tract and reaches the bloodstream. CD4+ Cells: Special white blood cells that coordinate the immune response to fight bacterial and viral infections. In HIV medicine, the CD4+ count is a marker for measuring immune-system health—normal CD4+ count is between 500 and 1500 per cubic milliliter of blood. HIV infection plus a CD4+ count below 200 is considered an AIDS diagnosis.
Chemokines: Proteins released by cells that stimulate activity between cells. Chemokines are intracellular messenger molecules secreted by CD8+ cells, whose major function is to attract immune cells to sites of infection.
Clinical Trial: a study done to test an experimental drug or procedure in human beings to see whether it is safe and effective, as well as to determine its proper dose. Compassionate Use: a process for providing experimental drugs on an individual basis to very sick patients who have no treatment options, despite the fact that there is insufficient data on the drug’s effectiveness. Often, case-by-case approval must be obtained from the FDA for compassionate use of a drug.
Complete Blood Count (CBC): a screening of the most important cellular components of the blood. A CBC includes the total white blood (leukocyte) count, counts of specific types of white blood cells, red blood cell count, hemoglobin level and platelet count.
Highly Active Antiretroviral Therapy (HAART): anti-HIV treatment, often including a combination of a protease inhibitor or non-nucleoside reverse transcriptase inhibitor and two reverse transcriptase inhibitors, whose purpose is to reduce viral load to undetectable levels.
Human Immunodeficiency Virus (HIV): a retrovirus that is believed to cause AIDS. HIV can be transmitted sexually, by blood-to-blood contact, and perinatally (from mother to child). HIV-1 is the most common version around the world, while HIV-2 is closely related to HIV-1, but is not as virulent as HIV-1 and is epidemic only in West Africa.
Immunosuppression: weakening of the immune response that occurs with HIV infection as well as with some antiviral or anticancer treatments. Immune system: The body’s complicated natural defense against disruption caused by invading foreign agents (e.g. microbes, viruses). There are two aspects of the immune system’s response to disease: innate and acquired. The innate part of the response is mobilized very quickly in response to infection and does not depend on recognizing specific proteins or antigens foreign to an individual’s normal tissue. It includes complements, macrophages, dendritic cells and granulocytes. The acquired, or learned, immune response arises when dendritic cells and macrophages present pieces of antigen to lymphocytes, which are genetically programmed to recognize very specific amino acid sequences. The ultimate result is the creation of cloned populations of antibody-producing B cells and cytotoxic T lymphocytes primed to respond to a unique pathogen.
Interferon (IFN): one of a number of antiviral proteins that modulates the immune response. Lipodystrophy: a disturbance of fat metabolism that involves the absence of fat and/or the abnormal distribution of fat in the body. Currently, “lipodystrophy” is not clearly defined and the term is used to refer to a variety of sydromes, including wasting in the face and extremities, an accumulation of abdominal fat, and breast enlargement. The cause is unknown, but it could be a result of HIV infection and/or antiretroviral therapy.
Lymphocyte: white blood cells that mature and reside in the lymphoid organs and are responsible for the acquired immune response. The two major types of lymphocytes are T cells and B cells.
Macrophage: A large immune cell that devours invading pathogens and other intruders. Stimulates other immune cells by presenting them with small pieces of the invader. Macrophages can harbor large quantities of HIV without being killed, acting as reservoirs of the virus.
Pathogen: any disease-provoking microorganism or material. q8h: an abbreviation used on prescriptions that means “take every 8 hours.” qd: an abbreviation used on prescriptions that means “take once a day.” From the Latin quaque die. Resistance: reduction in a pathogen’s sensitivity to a particular drug. Resistance is thought to result mainly from genetic mutation. In HIV, such mutations can change the structure of viral enzymes and proteins so that an antiviral drug cannot bind with them as effectively.
Seroconversion: development of detectable antibodies to HIV in the blood as a result of infection. It normally takes several weeks to several months for antibodies to the virus to develop after HIV transmission. When antibodies to HIV appear in the blood, a person will test positive in the standard ELISA test for HIV. Structured Treatment Interruption (STI): a planned treatment interruption, typically under medical supervision. The purpose of an STI varies; for example, it can be used to see whether a patient’s immune system can control HIV after it has been undetectable for years, or it can be used in an attempt to get a person’s viral population to revert from resistant to wild type. TID: a term used on prescriptions meaning “take three times a day,” from the Latin phrase ter in die.
Toxicity: the harmful side effects of a given drug. Undetectable: (Limit of Detection) refers to the sensitivity of a quantitative diagnostic test, such as the viral load assay. The limit of detection is the level below which the test can no longer accurately measure the amount of a substance, such as HIV RNA. If a person has an “undetectable” viral load, it does not mean that HIV is no longer present, but rather, that the test is not sensitive enough to measure the amount. Also called the “limit of quantification.”
Viral Load: Amount of measurable HIV virus found in blood or other body fluid sample. Virus: a noncellular pathogen composed essentially of genetic material (DNA or RNA) surrounded by a protein envelope. Viruses can reproduce only within living cells into which they inject their genetic material. The viral genes then subvert an infected cell’s normal chemical processes to create new virus particles, usually killing the cell in the process.
Wild Type Virus: naturally occurring HIV with an optimal genetic makeup and no artificially or lab-induced mutational defects. This term also refers to HIV that has not been exposed to antiviral drugs and therefore has not accumulated mutations conferring drug resistance.
For a more extended glossary, please visit http://www.gmhc.org/health/glossary.html, or call 1-800-HIV-0440 for a free copy of the Glossary of HIV/AIDS Related Terms. |
