Glossary of HIV Terms

What those medical words mean
Originally written and compiled by Enid Vázquez

A - CD - GH - LMN - OPR - ST - Z

A - C

active: refers to the effectiveness of drug therapy. For example, “His medications remain active [effective] against his HIV.”

ACTG: see “AIDS Clinical Trials Group”

ACT UP: AIDS Coalition to Unleash Power, an activist group formed in 1987.

acute HIV infection: recent infection (within the previous six months)

acute retroviral syndrome: symptoms that may be experienced during acute HIV infection, such as fever (including night sweats), diarrhea, nausea and vomiting, and headache.

adherence: taking medications as they should be taken (with or without food, on time, etc.).

adverse event: a negative drug side effect. A serious AE is one that is rated Grade 3–4, with 3 being “severe” and 4 being “life-threatening.”

AIDS: Acquired Immune Deficiency Syndrome. Advanced disease of HIV infection.

AIDS Clinical Trials Group: the largest and most prestigious network of HIV-related studies in the U.S. “ACTG” for short. There is a pediatric ACTG as well as one for adults.

antibody: a protein that the immune system forms to fight germs and other unwanted elements entering the body. Hence, the immune system forms HIV antibodies when the virus enters the body.

antiretroviral: an HIV drug (“anti-retroviral” means a drug that treats a retrovirus, like HIV). “ARV” for short.

arm: in research studies, one of the groups being studied. For example, “Participants in one arm were given once-daily doses of the drug.”

assay: a test

ASO: short for “AIDS service organization”

backbone: refers to the drugs someone is taking along with the medication considered to be the “star” of their treatment combination. For example, “He takes a backbone of two NRTIs with Sustiva.”

Bactrim: an antibiotic pill used to prevent a pneumonia (PCP) seen in people with AIDS

bioavailability: rate and extent to which a substance is absorbed and circulated in the body

blind, double-blind: when study participants don’t know what they’re receiving. “Double-blind” means that neither the researcher nor the participant know what the participant is being given. Participants do, however, know what they may possibly be receiving. Blinding helps eliminate bias.

blip: refers to a temporary increase in viral load (usually within 50 to 400) that then goes back down

boosted protease inhibitor: a protease inhibitor whose blood levels are increased with a small booster dose of the HIV drug Norvir (ritonavir), the only medication currently used for this purpose


CCR5 co-receptor: one of two co-receptors on the surface of T-cells that HIV uses to enter the cell

CCR5 inhibitor, CCR5 antagonist: a drug that blocks HIV’s use of the CCR5 co-receptor

CD4+ T-cell: a T-cell with a CD4 receptor on it. HIV’s favorite source for infection and spreading through the body. Often referred to simply as “T-cells.”

clinical progression: an HIV-related event, generally refers to disease or death

clinical: refers to actual effects on a patient’s health. For example, “The clinical effects are still unknown.” Also refers to care that people receive in a clinic, such as lab tests.

cocktail: refers to a drug combination

cognitive: refers to the working of the mind

co-factor: substances, microorganisms, or characteristics of individuals that might influence the progression of a disease or the likelihood of becoming ill

contraindication: refers to things that should not go together, such as medications that can not be taken at the same time.

control: in research study, something is tested against a “control.” For example, a placebo-controlled study compares an experimental treatment to a placebo.

co-morbidity: another illness besides HIV

compassionate use: the availability of an experimental drug or treatment for people who are seriously ill

CROI: Conference on Retroviruses and Opportunistic Infections, the largest HIV medical conference in the country

cytomegalovirus: a herpes virus considered an opportunistic infection. “CMV” for short. In AIDS, most commonly known for infecting the eyes, potentially leading to blindness, but can invade other organs.

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D - G

Data Safety Monitoring Board: an independent group of medical providers and community representatives that oversees a research study. “DSMB” for short.

discordant couple: when one person has HIV and the other doesn’t. Also called “sero-discordant.”

discordant response: when T-cells rise but viral load does not drop, or vice-versa (viral load drops but T-cells do not rise), while on therapy

double-blind: see “blind”

drug interaction: an effect that one drug has on another; an interaction could be positive or negative

dysplasia: abnormal development in skin, bone, and other tissues. If left untreated, may lead to cancer.

etiology: the cause of a disease

expanded access program (EAP): drug made available before final FDA approval to persons in great need of it

false positive: when an HIV test mistakenly notes that someone is positive for the virus.

FDA: short for U.S. Food and Drug Administration, which approves all medicines and medical devices on the market in this country

genotype resistance test: looks at the genetic make-up of a person’s HIV to help determine what medications would work. See also “phenotype resistance test.”

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H - L

hepatotoxicity: toxicity in the liver

highly active antiretroviral therapy: powerful HIV drug combination. “HAART” for short (pronounced “heart”).

HIV: human immunodeficiency virus.

holistic: looking at physical, spiritual, emotional, and mental aspects of an individual (the “whole” person)

host: the person with a disease. For example, “A variety of host factors can influence the progression of HIV.”

HVTN: HIV Vaccine Trials Network

immune reconstitution inflammatory syndrome (IRIS): illness occurring when the immune system becomes stronger with therapy and begins to activate underlying pathogens in order to fight them

immunologic: refers to the immune system, such as “immunologic response,” “immunologic progression,” etc. In HIV therapy, “immunologic response” refers to CD4+ T-cells, while “virologic response” refers to viral load.

in vitro: in the test tube

in vivo: in the body

late breaker: refers to medical reports accepted late at a conference

lipoatrophy: loss of fat. HIV medications have been associated with loss of fat in the arms, legs, and face (facial wasting).

lipodystrophy: a potential side effect of HIV therapy that may include increased blood levels of cholesterol and triglycerides; loss of fat in the arms, legs, and face (see “lipoatrophy”); and increased fat in the stomach and upper back (buffalo hump)

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MRSA: drug-resistant staph, stands for “methicillin-resistant Staphylococcus aureus.” “CA-MRSA” stands for “community-acquired MRSA.” Pronounced “mersa.”

MSM: stands for “men who have sex with men,” a category that includes males whether they consider themselves to be gay or not. Some MSM identify themselves as straight.

mutation: in HIV, refers to the virus changing itself in order to get around the effects of medications.

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N - O

neuropathy: any abnormal, degenerative, or inflammatory state of the peripheral nervous system; symptoms include numbness, tingling, or pain in the extremities (hands and feet).

non-inferiority study: an FDA-required standard; tries to show that the experimental treatment is not less effective than standard-of-care

nurse practitioner: a nurse who can prescribe medicine

off-label: refers to the use of a medication for which it is not approved, but for which there isevidence of effectiveness.

open-label: a drug study in which researchers and participants know what drugs or treatments, including experimental, are being given

opportunistic infection: caused by a microbe that can normally exist peacefully in a person’s body, but which can cause illness when the immune system is weak, OI for short

optimized background therapy: usually used in clinical studies; refers to studies where a person’s current therapy is improved with available medications (“optimized”). A person may or may not receive the experimental drug being tested in the study (on top of their OBT).

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p24 antigen: a protein fragment of HIV

P450 pathway: the pathway through which many drugs, herbs, and supplements are metabolized in the liver; often the reason certain herbs/supplements can’t be taken with drugs

Pap smear: a test that collects cells from the cervix or anus to check for cancer or pre-cancerous changes. Named for Papanicolaou, the doctor who invented the test.

pathogen: a microorganism that can cause disease. Pathogens include viruses, bacteria, fungi, and parasites.

pathogenesis: origin and development of disease.

pelvic inflammatory disease (PID): inflammation of the pelvic area, which may lead to infertility, ectopic pregnancy, or scarring of the fallopian tubes. PID is usually caused by untreated sexually transmitted infections, such as chlamydia or gonorrhea.

peripheral neuropathy: a disorder of the nerves, usually involving the hands, feet, arms, and legs. A potential side effect of some HIV medications.

Phase 1, 2, 3, and 4: the four stages of a clinical study. “Pre-clinical” generally refers to test tube measurements or testing in animals.

phenotype resistance test: a test tube measurement that puts an HIV blood sample against each of the HIV drugs to see which ones are effective against that particular individual’s virus. See also “genotype resistance test.”

placebo: a dummy pill used in studies. Placebos are used to see if the experimental treatment makes a difference. See “control.”

post-exposure prophylaxis: HIV medications taken after exposure to the virus in an attempt to avoid infection. “PEP” for short.

pre-exposure prophylaxis: HIV medications taken before exposure to the virus in an attempt to avoid infection. “PrEP” for short. Not yet a medical standard. PrEP is still being studied for efficacy.

prophylaxis: something used as prevention. For example, condoms are a prophylaxis against disease.

protocol: In medicine, refers to the plan for a study or course of treatment.

providers: health care workers, may refer to other services, such as those of social workers

PWA: short for “people (or person) with AIDS”

PWH/A: short for “people (or person) with HIV/AIDS’

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R - S

randomized: in a research study, the process of placing people into different categories in a way that avoids skewing the results.

rapid HIV testing: an HIV test that gives results in 20 minutes.

rebound: generally used to refer to a rising viral load, especially to the level it was when therapy was started

regimen: treatment combination

resistance: the ability of microbes, including HIV, to change their structure so that drugs can no longer affect them

retrovirus: a virus that works “backwards,” differently from most viruses. Most viruses use their DNA to change a person’s RNA. A retrovirus uses its RNA to insert itself into a person’s DNA.

salvage therapy: advanced therapy; the second or third, etc. round; for people with advanced disease

second generation: refers to a new drug that works differently from the older medications in its drug class. Usually refers to an improved resistance pattern (harder for HIV to develop resistance to).

seropositive: in HIV, means a person tests positive for the virus

sero-discordant: generally refers to a couple where one person is HIV-positive and the other is not

serum: the clear, thin, and sticky fluid that separates from blood when it clots. Serum, not whole blood, is the actual fluid used for measuring T-cells and viral load.

sexually transmitted infection: exactly what it says. “STI” for short.

suppressed: “suppressed virus” is one of the goals of HIV therapy, simply, keeping the viral load down as low as possible, ideally at undetectable levels

susceptibility: when HIV has not developed drug resistance to a medication and that medication can still effectively fight it

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T - Z

T-cell: An immune system cell that is made in, and released from, the thymus (hence the letter “T”). Also called T-helper cells. See also “CD4+ T-cell.”

treatment-experienced: a person who has experience with antiretroviral therapy

treatment failure: generally refers to a detectable viral load, or a rising one, while on treatment

treatment-naïve: someone who has never taken HIV medicine.

trial: another word for a research study

tropism: the type of co-receptor that HIV can use to enter a cell. A person’s HIV can be “CCR5-tropic,” “CXCR4-tropic,” “dual tropic” (the virus uses both co-receptors), or “mixed tropic” (the virus is partially CCR5-tropic and partially X4-tropic).

undetectable: a viral load below the limit of a test’s detection, generally 50. Virus is still in the person’s blood, but not at a level that can be picked up by the test.

ultrasensitive assay: in viral loads, a test that measures as low as 50 copies/mL viral load

vertical transmission: HIV infection passed on from a mother to infant during or around the time of pregnancy, or during breastfeeding

viral load: the quantity of virus measured in blood (serum), other fluid, or tissue

virologic: refers to blood. In HIV, “virologic” usually refers to viral load.

wild-type virus: virus that has not developed resistance. Often the type of virus with which a person is infected, although people can be infected with resistant virus.

Sources include AIDSInfo at the National Institutes of Health and the Project Inform HIV Drug Book.

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