Definitions of HIV Glossary

A
acute infection: The time period just after a person is first infected with HIV and before he/she is able to mount an antibody response that is detectable by conventional HIV tests. Frequently accompanied by “flu-like” symptoms such as fever, rash, enlarged lymph nodes, joint and muscle aches, fatigue, etc. Also called primary infection. See HIV Basics section Symptoms of HIV for a description of the early infection period and symptoms.

adverse reaction: (Adverse Event.) An unwanted effect caused by the administration of drugs. Onset may be sudden or develop over time (See Side Effects).

advocacy and support groups: Organizations and groups that actively support participants and their families with valuable resources, including self-empowerment and survival tools.

antibody: An infection-fighting protein molecule in blood or body fluid that tags, neutralizes, and helps destroy bacteria, viruses or other harmful toxins. Antibodies, known generally as immunoglobulins, are made by white blood cells in response to a foreign substance. Each specific antibody binds only to the specific antigen that stimulated its production. (See also immunoglobulin; binding antibody; enhancing antibody; functional antibody; neutralizing antibody.)

antibody-mediated immunity: also called humoral immunity. Immunity that results from the activity of antibodies in blood and lymphoid tissue.

antigen: An antigen is a foreign substance or protein in the body that can trigger an immune response. This response results in the production of an antibody (a protein that is made by white blood cells) that tries to combat the antigen.

apoptosis: cellular suicide, also known as programmed cell death. A possible mechanism used by HIV to suppress the immune system. HIV may cause apoptosis in both HIV-infected and HIV-uninfected immune system cells.

approved drugs: In the United States, the Food and Drug Administration (FDA) must approve a substance as a drug before it can be marketed. The approval process involves several steps including pre-clinical laboratory and animal studies, clinical trials for safety and efficacy, filing of a New Drug Application by the manufacturer of the drug, FDA review of the application, and FDA approval/rejection of application [See Food and Drug Administration].

arm: A group of participants in a comparative clinical trial all of whom receive the same treatment, intervention or placebo. The other arm(s) receive(s) a different treatment. Most randomized trials have two "arms," which may be comparing either a new drug with a placebo, or comparing two drugs to each other. Some trials have three "arms," or even more. [See Randomized Trial].

ART: Formally known as HAART [Highly Active Antiretroviral Treatment], ART is defined as treatment with at least three active anti-retroviral medications (ARV’s), typically two nucleoside or nucleotide reverse transcriptase inhibitors (NRTI’s) plus a non-nucleoside reverse transcriptase inhibitor (NNRTI) or a protease inhibitor (PI) or another NRTI called abacavir (Ziagen). ART is often called the drug “cocktail” or triple-therapy.

attenuated virus: weakened. Attenuated viruses are often used as vaccines because they can no longer produce disease but still stimulate a strong immune response, like that to the natural virus. Examples of attenuated virus vaccines include oral polio, measles, mumps, and rubella vaccines.

B
baseline: Information gathered at the beginning of a clinical trial, just before a participant starts to receive the treatment(s) that are part of the study. At this reference point, measurable values such as CD4 count are recorded. The safety and efficacy of a drug are often determined by monitoring changes from the baseline values.

bDNA (branched DNA) assay: laboratory test for measuring the amount of virus in blood plasma. The test detects an amplified luminescent signal whose brightness depends on the amount of viral RNA present.

bias: When a point of view prevents impartial judgment on issues relating to the subject of that point of view. In clinical studies, bias is controlled by blinding and randomization [See Blind and Randomization].

blinded study: A clinical trial in which participants don't know whether they are in the experimental or control arm of the study. [See double blind study].

b lymphocyte (B cell): one of the two major classes of lymphocytes, B lymphocytes are white blood cells of the immune system that are derived from the bone marrow and spleen. B cells develop into plasma cells, which produce antibodies.

C
CAB: Stands for Community Advisory Board. Every clinical research group should have an established CAB whose members are made up the demographics of the HIV epidemic reflecting the age, gender, racial and ethnic populations, multiple educations/literacy/language levels of the community that is served. The Community Advisory Board assists the research team in the selection and implementation of studies. This multidisciplinary group of volunteers works to integrate community involvement in order to advance HIV/AIDS research. An important mission of the CAB is to provide an opportunity for our affected communities to understand the clinical research process; voice concerns regarding specific clinical studies, their development, implementation and outcomes; give assistance concerning issues related to the accrual and retention of trial participants; give clinical trial participants necessary advocacy; forge a viable partnership that will lead to improved knowledge of HIV/AIDS disease; give a means to address grievance issues; and promote ethical research purposes and practices.

CD4 cell counts: Also known as “helper” T-cells, help by mobilizing your immune defense when your body has an infection. Therefore your CD4 cell count is a measure of your immune system’s health. [See Reading Test Results].

CD8 T lymphocyte: immune cell that carries the "cluster of differentiation 8" (CD 8) marker. CD8 T cells may be cytotoxic T lymphocytes or suppressor T cells. [See also cytotoxic T lymphocyte (CTL): T cell].

cell-mediated immunity (cellular immunity): The immune response coordinated by helper T cells and CTLs. This branch of the immune system targets cells infected with microorganisms such as viruses, fungi and certain bacteria.

chemistry screen: Measures essential chemicals produced by your blood and can help diagnose infections and drug side effects. [See Reading Test Results].

clinical: Pertaining to or founded on observation and treatment of participants, as distinguished from theoretical or basic science.

clinical endpoint: See Endpoint.

clinical investigator: A medical researcher in charge of carrying out a clinical trial's protocol.

clinical trial: A clinical trial is a research study designed to answer specific questions about vaccines or new therapies or new ways of using known treatments. Clinical trials (also called medical research and research studies) are used to determine whether new drugs or treatments are both safe and effective. Carefully conducted clinical trials are the fastest and safest way to find treatments that work in people. Trials are in four phases: Phase I tests a new drug or treatment in a small group; Phase II expands the study to a larger group of people; Phase III expands the study to an even larger group of people; and Phase IV takes place after the drug or treatment has been licensed and marketed. [See Phase I, II, III, and IV Trials].

cohort: a group of individuals with some characteristics in common. For example, a trial might include two cohorts, a group that has hepatitis and HIV, and a group that does not have heptitis.

complete blood count [CBC]: A measure of the health of your blood, including the quality and quantity of its white and red blood cells, the CBC includes 13 tests. 3 main tests: White Blood Cell Count (WBC), Hemoglobin (HGB), Platelets. [See Reading Test Results]

confidentiality regarding trial participants: Refers to maintaining the confidentiality of trial participants including their personal identity and all personal medical information.

contraindication: A specific circumstance when the use of certain treatments could be harmful.

control group: The control group in a clinical trial is the group of subjects that does not receive the experimental treatment, but receives either the currently approved standard treatment for the disease or an inactive substance [also called placebo].

controlled trials: Control is a standard against which experimental observations may be evaluated. In clinical trials, one group of participants is given an experimental drug, while another group (i.e., the control group) is given either a standard treatment for the disease or a placebo.

cytokines: a protein produced by white blood cells, that acts as a messenger between cells. Cytokines can stimulate or inhibit the growth and activity of various immune cells. Cytokines are essential for a coordinated immune response. HIV replication is regulated by a delicate balance among the body's own cytokines. By altering that balance one can change the replication of the virus in the test tube and potentially even in the body.

cytotoxic t lymphocyte (CTL): A lymphocyte that is able to kill foreign cells marked for destruction by the cellular immune system. CTLs can destroy cancer cells and cells infected with viruses, fungi, or certain bacteria. CTLs are also known as killer T cells; they carry the CD8 marker. CTLs kill virus-infected cells, whereas antibodies generally target free-floating viruses in the blood. See also CD8 (T8) Cells.

D
data safety and monitoring board [DSMB]: An independent committee, composed of community representatives and clinical research experts, that reviews data while a clinical trial is in progress to ensure that participants are not exposed to undue risk. A DSMB may recommend that a trial be stopped if there are safety concerns or if the trial objectives have been achieved.

detuned assay: At present the standard way that we know if someone is HIV positive is to look to see if antibody [the body’s usual reaction to an infection] if present for HIV. The Detuned Assay attempts to determine how recently someone has been infected by looking for early versus mature antibodies. A Detuned Assay report that shows early antibodies may indicate that you have been infected less than 3 months. A Detuned Assay report that shows you have mature antibodies may indicate that you have been infected for longer than 3 months. This lab test is only performed in research at this time.

dose ranging study: A clinical trial in which two or more doses of an agent (such as a drug) are tested against each other to determine which dose works best and is least harmful.

double-blind study: A clinical trial design in which neither the participating individuals nor the study staff knows which participants are receiving the experimental drug or vaccine, or which are receiving the control or (another therapy) (The control is the currently-approved standard treatment for the disease or an inactive substance called a placebo.) [See Single Blind Study and Double Blind Study].

drug-drug interaction: A modification of the effect of a drug when administered with another drug. The effect may be an increase or a decrease in the action of either substance, or it may be an adverse effect that is not normally associated with either drug.

drug resistance: Occurs when the virus a person is infected with is no longer sensitive to the medications taken. Even when the viral load is undetectable, a small amount of virus is still replicating. The ‘copies’ (of the replicating viruses) that survive are those that the drug cannot suppress. The surviving copies have genes that have mutated to elude capture by the drug. Sooner or later, this mutated virus reaches a critical mass and ‘breaks through’[See Reading Test Results].

drug resistance testing: Measures which of the 16 HIV medications an infected person’s virus may have developed resistance to[See Reading Test Results].

DSMB: See Data Safety and Monitoring Board.

E
efficacy: (Of a drug or treatment). The maximum ability of a drug or treatment to produce a result regardless of dosage. A drug passes efficacy trials if it is effective at the dose tested and against the illness for which it is prescribed. In the procedure mandated by the FDA, Phase II clinical trials gauge efficacy, and Phase III trials confirm it [See Food and Drug Administration] [See Phase 1, 2, 3, and 4 Trials].

eligibility criteria: Summary criteria for participant selection; includes Inclusion and Exclusion criteria. [See Inclusion/Exclusion Criteria].

ELISA (enzyme-linked immunoabsorbent assay) : a blood test that detects antibodies based on a reaction that leads to a color change in the test tube. The HIV ELISA is commonly used as the initial screening test because it is relatively easy and inexpensive to perform. Because the HIV ELISA is designed for the greatest sensitivity : that is, it detects all persons with HIV antibodies as well as some who don't have them (false positives) : a positive HIV ELISA test must be confirmed by a second, more specific test such as an HIV Western Blot.

empirical: Based on experience or observational information not necessarily on proven scientific data.

endpoint: Overall outcome that the protocol is designed to evaluate.

envelope: outer surface of a virus, also called the coat. Not all viruses have an envelope. (See also virus; env.)

enzyme: a protein produced by cells to accelerate a specific chemical reaction without itself being altered. Enzymes are generally named by adding the ending "-ase" to the name of the substance on which the enzyme acts (for example, protease is an enzyme that acts on proteins).

epidemiology: The branch of medical science that deals with the study of incidence and distribution and control of a disease in a population.

exclusion/inclusion criteria: See Inclusion/Exclusion Criteria.

F
FDA: See Food and Drug Administration.

Food and Drug Administration [FDA]: The U.S. Department of Health and Human Services agency responsible for ensuring the safety and effectiveness of all drugs, biologics, vaccines, and medical devices, including those used in the diagnosis, treatment, and prevention of HIV infection, AIDS, and AIDS-related opportunistic infections. The FDA also works with the blood banking industry to safeguard the nation's blood supply. Internet address: http://www.fda.gov

G

gp120: glycoprotein 120. One of the proteins that forms the envelope of HIV. gp120 projects from the surface of HIV and binds to the CD4 molecule on helper T cells. gp120 has been a logical target for experimental HIV vaccine because the outer envelope is the first part of the virus that encounters antibody.

gp160: glycoprotein 160, a precursor of HIV envelope proteins gp41 and gp 120.

H
HAART: Stands for Highly Active Antiretroviral Treatment. HAART is defined as treatment with at least three active anti-retroviral medications (ARV’s), typically two nucleoside or nucleotide reverse transcriptase inhibitors (NRTI’s) plus a non-nucleoside reverse transcriptase inhibitor (NNRTI) or a protease inhibitor (PI) or another NRTI called abacavir (Ziagen). HAART is often called the drug “cocktail” or triple-therapy.

half-life: the time required for half the amount of a substance to be eliminated from the body or to be converted to another substance(s).

helper T cell: lymphocyte bearing the CD4 marker. Helper T cells are the chief regulatory cells of the immune response. They are responsible for many immune system functions, including turning antibody production on and off, and are the main target of HIV infection. (See also CD4+ T lymphocyte.)

HIV viral set point: The rate of virus replication that stabilizes and remains at a particular level in each individual after the period of primary infection.

human immunodeficiency virus type 1 (HIV-1): The retrovirus isolated and recognized as the cause of AIDS. HIV-1 is classified as a lentivirus in a subgroup of retroviruses. The genetic material of a retrovirus such as HIV is the RNA itself. HIV converts its RNA into DNA and inserts into the host cell's DNA, preventing the host cell from carrying out its natural functions and turning it into an HIV factory.

human immunodeficiency virus type 2 (HIV-2): A virus closely related to HIV-1 that has also been found to cause AIDS. It was first isolated in West Africa. Although HIV-1 and HIV-2 are similar in their viral structure, modes of transmission, and disease manifestation, HIV-2 is less aggressive than HIV-1 and does not always react to HIV medications in the same way as HIV-1.

hypothesis: A supposition or assumption advanced as a basis for reasoning or argument, or as a guide to experimental investigation.

I
immune complex: the result of a reaction between an antigen and a specific antibody. This combination of antigen bound by antibody may or may not cause adverse effects in a person.

immune deficiency: a breakdown or inability of certain parts of the immune system to function, thus making a person susceptible to diseases (“opportunistic infections”) that they would not ordinarily develop.

immunity: natural or acquired resistance provided by the immune system to a specific disease. Immunity may be partial or complete, specific or nonspecific, long-lasting or temporary.

immunization: the process of inducing immunity by administering an antigen (vaccine) that is derived from or similar to the infecting agent, in order to allow the immune system to prevent infection or illness when it subsequently encounters the infectious agent.

immunogen: a substance capable of provoking an immune response. Also called an antigen.

immunogenicity: the ability of an antigen or vaccine to stimulate immune responses.

immunotherapy: a treatment that stimulates or modifies the body's immune response.

inclusion/exclusion criteria: The medical or social standards determining whether a person may or may not be allowed to enter a clinical trial. These criteria are based on such factors as age, gender, the type and stage of a disease, previous treatment history, and other medical conditions. It is important to note that inclusion and exclusion criteria are not used to reject people personally, but rather to identify appropriate participants and keep them safe.

IND: See Investigational New Drug.

informed consent: The process of learning the key facts about a clinical trial before deciding whether or not to participate. It is also a continuing process throughout the study to provide information for participants. To help someone decide whether or not to participate, the doctors and nurses involved in the trial explain the details of the study. There is also an informed consent document which states why the particular clinical trial is being done, what procedures will be done during the course of the study, what possible risks there may be and information about the rights and responsibilities of a study participant. This document must be signed by the clinical trial participant before any study procedure can begin.

informed consent document: A document that describes the rights of the study participants, and includes details about the study, such as its purpose, duration, required procedures, and key contacts. Risks and potential benefits are explained in the informed consent document. The participant then decides whether or not to sign the document. Informed consent is not a contract, and the participant may withdraw from the trial at any time.

Institutional Review Board [IRB]: 1. A committee of physicians, statisticians, researchers, community advocates, and others that ensures that a clinical trial is ethical and that the rights of study participants are protected. All clinical trials in the U.S. must be approved by an IRB before they begin. 2. Every institution that conducts or supports biomedical or behavioral research involving human participants must, by federal regulation, have an IRB that initially approves and periodically reviews the research in order to protect the rights of human participants.

intent to treat: Analysis of clinical trial results that includes all data from participants in the groups to which they were randomized [See Randomization] even if they never received or discontinued the treatment or if they leave the study before completing all the required visits.

intervention name: The generic name of the precise intervention being studied.

intervention: Primary interventions being studied. Types of interventions are Drug, Gene Transfer, Vaccine, Behavior, Device, or Procedure.

investigational new drug: A new drug, antibiotic drug, or biological drug that is used in a clinical investigation. It also includes a biological product used in vitro for diagnostic purposes. Investigational New Drug is a status given to an experimental drug after the FDA agrees that it can be tested in people.

in vitro: an artificial environment created outside a living organism (e.g., in a test tube or culture plate) used in experimental research to study a disease or biological process.

in vivo: testing within a living organism, e.g., human or animal studies.

isolate: a particular strain of HIV-1 taken from a person.

IRB: See Institutional Review Board.

J

K
 

L
lactic acidosis: caused by very high levels of lactic acid; lactic acidosis is a serious, sometimes life-threatening condition that can occur when the body's tissues do not get enough oxygen. Levels of lactic acid can increase when the liver is severely damaged or diseased, because the liver normally breaks down lactic acid.

live-vector vaccine: a vaccine that uses a non-disease-causing organism (virus or bacterium) to transport HIV or other foreign genes into the body, thereby stimulating an effective immune response to the foreign products. This type of vaccine is important because it is particularly capable of inducing CTL activity (CTLs - cytotoxic t lymphocytes - kill virus-infected cells). Examples of organisms used as live vectors in HIV vaccines are canarypox and vaccinia.

lymphocyte: a type of white blood cell produced in the lymphoid organs that is primarily responsible for immune responses. Present in the blood, lymph and lymphoid tissues. (See also B cell and T cell.)

lymphoid tissues: include tonsils, adenoids, lymph nodes, spleen, thymus, and other tissues. These organs act as the body's filtering system, trapping invaders (foreign particles, e.g., bacteria and viruses) and presenting them to squadrons of immune cells that gather in the tissue.

lymphoma: Cancer of the lymphoid tissues. Lymphomas are often described as being large cell or small cell types, cleaved or non-cleaved, or diffuse or nodular. The different types often have different prognoses (i.e., prospect of survival or recovery). Lymphomas can also be referred to by the organs where they are active, such as CNS lymphomas, which are in the central nervous system, and GI lymphomas, which are in the gastrointestinal tract. The types of lymphomas most commonly associated with HIV infection are called non-Hodgkin's lymphomas or B cell lymphomas. In these types of cancers, certain cells of the lymphatic system grow abnormally. They divide rapidly, growing into tumors.

M
macrophage: a large immune system cell in the tissues that devours invading pathogens and other intruders. Macrophages stimulate other immune cells by presenting them with small pieces of the invaders. Macrophages also can harbor large quantities of HIV without being killed, acting as reservoirs of the virus.

memory cell: memory cells are a subset of T cells and B cells that have been exposed to specific antigens and can then proliferate (recognize the antigen and divide) more readily when the immune system re-encounters the same antigens.

mucosal immunity: resistance to infection across the mucous membranes. Mucosal immunity depends on immune cells and antibodies present in the linings of reproductive tract, gastrointestinal tract and other moist surfaces of the body exposed to the outside world.
 

N
natural history study: Study of the natural development of something (such as an organism or a disease) over a period of time.

neuropathy: The name given to a group of disorders involving nerves. Symptoms range from a tingling sensation or numbness in the toes and fingers to paralysis. Can be a result of HIV infection itself or of antiretroviral therapy. It is estimated that 35% of persons with HIV disease have some form of neuropathy. [See Peripheral Neuropathy]

neutralizing antibody: An antibody that keeps a virus from infecting a cell, usually by blocking receptors on the cell or the virus.

Neutropenia: An abnormal decrease in the number of neutrophils (the most common type of white blood cells) in the blood. The decrease may be relative or absolute. Neutropenia may also be associated with HIV infection or may be drug induced.

new drug application [NDA]: An application submitted by the manufacturer of a drug to the FDA - after clinical trials have been completed - for a license to market the drug for a specified indication.

NK cell (natural killer cell): a non-specific lymphocyte. NK cells, like killer T cells, attack and kill cancer cells and cells infected by microorganisms. NK cells are "natural" killers because they do not need to recognize a specific antigen in order to attack and kill.

non-hodgkin's lymphoma (NHL): A lymphoma (cancer of the lymphoid tissues) made up of B cells and characterized by nodular or diffuse tumors that may appear in the stomach, liver, brain, and bone marrow of persons with HIV. After Kaposi's Sarcoma, NHL is the most common opportunistic cancer in persons with AIDS.

normalized inhibitory quotient [NIQ]: tells the drug level increase needed of a specific antiretroviral drug required to stop HIV from growing in your blood in order to lower your viral load.

nucleic acid: organic substance found in all living cells, in which the hereditary information is stored and from which it can be transferred. Nucleic acid molecules are long chains that generally occur in combination with proteins. The two chief types are DNA (deoxyribonucleic acid), found mainly in cell nuclei, and RNA (ribonucleic acid), found mostly in cytoplasm.

Nucleoside: a building block of nucleic acids, DNA, or RNA, the genetic material found in living organisms. Nucleosides are nucleotides without the phosphate groups.

nucleoside analog: an artificial copy of a nucleoside. When incorporated into the DNA or RNA of a virus during viral replication, the nucleoside analog acts to prevent production of new virus. Nucleoside analogs may take the place of natural nucleosides, blocking the completion of a viral DNA chain during infection of a new cell by HIV. The HIV enzyme reverse transcriptase is more likely to incorporate the nucleoside analogs into the DNA it is constructing than is the DNA polymerase normally used for DNA creation in cell nuclei.

nucleoside reverse transcriptase inhibitor (NRTI): a nucleoside analog antiretroviral drug whose chemical structure is made up of a modified version of a natural nucleoside. These compounds suppress reproduction of retroviruses by interfering with the reverse transcriptase enzyme. The nucleoside analogs cause premature termination of the proviral (viral precursor) DNA chain. All NRTIs require phosphorylation, (the process of introducing a phosphate group into an organic molecule), in the host's cells prior to their incorporation into the viral DNA.

Nucleotide: Nucleotides are the building blocks of nucleic acids, DNA, and RNA. Nucleotides are composed of phosphate groups, a five-sided sugar molecule (ribose sugars in RNA, deoxyribose sugars in DNA), and nitrogen-containing bases. These fall into two classes: pyrimidines and purines. A nucleotide without its phosphate group is called a nucleoside.

O
off-label use: A drug prescribed for conditions other than those approved by the FDA.

open-label trial: a clinical trial in which the study doctor and the participant know which drug(s) or vaccine the study participant is receiving.

opportunistic infection: an illness caused by an organism that usually does not cause disease in a person with a normal immune system. People with advanced HIV infection suffer opportunistic infections of the lungs, brain, eyes and other organs.

P
p24: a protein in HIV's inner core. The p24 antigen test looks for the presence of this protein in a person's blood.

pathogen: any disease-producing microorganism or material.

pathogenesis: the origin and development of a disease. More specifically, it's the way a microbe (bacteria, virus, etc.) causes disease in its host.

PCR (polymerase chain reaction): a sensitive laboratory technique used to detect the amount of HIV RNA in the blood. PCR is used to measure viral load in persons infected with HIV.

peer review: Review of a clinical trial by experts chosen by the study sponsor. These experts review the trials for scientific merit, participant safety, and ethical considerations.

Peptide: a short compound formed by linking two or more amino acids. Proteins are made of multiple peptides.

pharmacokinetics: the processes of absorption, distribution, metabolism and excretion of a drug or vaccine.

phase 1 trials: a closely monitored clinical trial of a drug or vaccine conducted in a small number of healthy volunteers. A Phase 1 trial is designed to determine the vaccine's safety in humans, its metabolism and pharmacologic actions, and side effects associated with increasing doses.

phase 2 trials: controlled clinical study of a drug or vaccine to identify common short-term side effects and risks associated with the drug and to collect some information on its effectiveness against the disease being studied. Phase 2 trials enroll some volunteers who have the same characteristics as persons who would be enrolled in an efficacy (Phase 3) trial of a drug or vaccine. Phase 2 trials enroll up to several hundred participants and have more than one arm.

phase 3 trials: expanded controlled and uncontrolled trials conducted after preliminary evidence suggesting effectiveness of the drug at an optimally selected dose and schedule has been obtained. Phase 3 trials are also intended to gather additional information about safety needed to evaluate the overall benefit-risk relationship of the drug and to provide an adequate basis for physician labeling. Phase 3 trials usually include several hundred to several thousand volunteers.

phase 4 trials: Post-marketing studies to delineate additional information including the drug's risks, benefits, and optimal use.

phosphate: a substance (called an electrolyte) that carries an electrical charge when dissolved in blood. Most of the body's phosphate (about 85%) is found in bones. The rest of it is stored in tissues throughout the body. (Electrolytes are minerals found naturally in the body. They include potassium, calcium, sodium, and magnesium. Electrolytes are needed to fight infection and to keep the body's balance of fluids at the proper level and to maintain normal functions, such as heart rhythm, muscle contraction, and brain function.)

placebo: A placebo is an inactive pill, liquid, or powder that has no treatment value. In clinical trials, experimental treatments are often compared with placebos to assess the treatment's effectiveness. In some studies, the participants in the control group will receive a placebo instead of an active drug or treatment. No sick participant receives a placebo if there is a known beneficial treatment. [See Placebo Controlled Study].

placebo controlled study: A method of investigation of drugs in which an inactive substance (the placebo) is given to one group of participants, while the drug being tested is given to another group. The results obtained in the two groups are then compared to see if the investigational treatment is more effective in treating the condition.

placebo effect: A physical or emotional change, occurring after a substance is taken or administered, that is not the result of any special property of the substance. The change may be beneficial, reflecting the expectations of the participant and, often, the expectations of the person giving the substance.

polyvalent vaccine: a vaccine that is produced from multiple viral strains, or is made to induce immune responses against multiple strains.

preclinical: Refers to the testing of experimental drugs in the test tube or in animals - the testing that occurs before trials in humans may be carried out.

prevention trials: Refers to trials to find better ways to prevent disease in people who have never had the disease or to prevent a disease from returning. These approaches may include medicines, vitamins, vaccines, minerals, or behavioral changes.

preventive HIV vaccine: a vaccine designed to prevent getting infected from HIV.

primary care provider: Refers to a health care professional who provides you with comprehensive medical care. A Primary Care Provider can be a medical doctor or physician [MD], a physician’s assistant [PA] or a nurse practitioner [NP]. He or she conducts your regular physical exams and takes care of your health care needs. When necessary, your primary care provider refers you to a specialist for further examination and treatment.

prophylaxis: prevention of disease.

protease inhibitor: one of a class of anti-HIV drugs designed to inhibit the enzyme protease and interfere with virus replication. Protease inhibitors prevent HIV precursor proteins from dividing into smaller cells of active proteins, a process that normally occurs when HIV reproduces.

protocol: protocol: the detailed plan for a clinical trial that is designed to answer specific research questions. The protocol describes what types of people may participate in the trial; the schedule of tests, procedures, medications, and dosages; and, the length of the study. While in a clinical trial, participants are seen at regular visits which have been determined in the protocol. At these visits, the research staff monitors participants’ health and may take blood or perform other tests to evaluate the safety and effectiveness of the treatment. [See Inclusion/Exclusion Criteria].

Q
quality of life trials [or supportive care trials]: Refers to trials that explore ways to improve comfort and quality of life for individuals with a chronic illness.
 

R
randomized trial: a study in which participants are assigned by chance to one of two or more intervention arms or regimens. Randomization minimizes the differences among groups by equally distributing people with particular characteristics among all the trial arms. [See Arm and Placebo].

receptor: a molecule on the surface of a cell that serves as a recognition or binding site for antigens, antibodies or other cellular or immunologic components.

recombinant DNA technology: the technique by which genetic material from one organism is inserted into a foreign cell in order to mass produce the protein encoded by the inserted genes.

resistance testing:
-genotype testing: a type of resistance test that looks for changes (mutations) in HIV that may be associated with drug resistance (this is when HIV is no longer controlled by drugs).
-phenotype testing: a kind of resistance testing that, instead of using mutation analysis, grows the virus in the presence of various concentrations of drug to see which drugs the HIV is still sensitive to (not resistant to). Standard phenotype tests take approximately 4 weeks to show results and the test is very expensive.
-virtual phenotype: a system used to give the same information as the standard phenotype test – that is, information about which drugs will work to control the HIV -- by comparing information gathered from over 35,000 actual phenotype tests to see which drugs will still have an effect on those mutations. This is done by entering the results from a genotype test into the database of available information. All these tests can be very helpful in making treatment decisions about which medications will work against the mutations one has developed in order to try to get the HIV under control and reduce viral load.

retrovirus: HIV and other viruses that carry their genetic material in the form of RNA rather than DNA and have the enzyme, reverse transcriptase, that can transcribe it into DNA. In most animals and plants, DNA is usually made into RNA, hence "retro" is used to indicate the opposite direction.

reverse transcriptase: the enzyme produced by HIV and other retroviruses that enables them to direct a cell to synthesize DNA from their viral RNA.


risk-benefit ratio: The risk to individual participants versus the potential benefits. The risk/benefit ratio may differ depending on the condition being treated.

RNA (ribonucleic acid): a single-stranded molecule composed of chemical building blocks, similar to DNA. The RNA segments in cells represent copies of portions of the DNA sequences in the nucleus. RNA is the sole genetic material of retroviruses.

S
screening trials: Refers to trials which test the best way to detect certain diseases or health conditions.

serostatus: positive or negative results of a diagnostic test, such as an ELISA, for a specific antibody, in this case HIV.

side effects: Any undesired actions or effects of a drug or treatment. Negative or adverse effects may include headache, nausea, hair loss, skin irritation, or other physical problems. Experimental drugs must be evaluated for both immediate and long-term side effects [See Adverse Reaction].

single-blind study: A study in which one party, either the investigator or participant, is unaware of what medication the participant is taking. [See Blind and Double-Blind Study].

standard treatment: A treatment currently in wide use and approved by the FDA, considered to be effective in the treatment of a specific disease or condition.

standards of care: Treatment regimen or medical management based on state of the art participant care.

statistical significance: the probability that an event or difference occurred as the result of the intervention (drug or vaccine) rather than by chance alone. This probability is determined by using statistical tests to evaluate collected data. Guidelines for defining significance are chosen before data collection begins.

stratification: separation of a study cohort into subgroups or strata according to specific characteristics such as age, gender, etc., so that these differences which might affect the outcome of the study, can be taken into account.

sterilizing immunity: an immune response that completely prevents the establishment of an infection.

study endpoint: A primary or secondary outcome used to judge the effectiveness of a treatment

study type: The primary investigative techniques used in an observational protocol; types are Purpose, Duration, Selection, and Timing.

surrogate marker: an indirect measure of disease progression. In HIV disease, the number of CD4+ T cells per cubic millimeter of blood is often used as a surrogate marker.

T
therapeutic HIV vaccine: a vaccine designed to boost the immune response to HIV in a person already infected with the virus. Also referred to as an immunotherapeutic vaccine.

T lymphocyte proliferation assay: The Lymphocyte Proliferation Assay (LPA) is a test used to measure how well a person’s immune system is functioning by testing the memory of T cells to recognize antigens or microbes such as candida, tetanus toxoid (TT)., cytomegalovirus (CMV) antigen, varicella zoster virus (VZV) antigen, and HIV-1 antigens (e.g., gp120 and p24) This proliferative response of lymphocytes occurs only if the patient has been immunized to that antigen, either by having recovered from an infection with the microorganism containing that antigen, or by having been vaccinated. Most people will respond to at least one of several common microbial antigens. LPA can be used to measure improvements in immunological function following antiretroviral therapy, to measure the development of anti-HIV immune responses following the administration of an HIV-vaccine, and to detect the presence of immune responses against specific opportunistic pathogens.
 

toxicity: An adverse effect produced by a drug that is detrimental to the participant's health. The level of toxicity associated with a drug will vary depending on the condition which the drug is used to treat.

treatment IND: IND stands for Investigational New Drug application, which is part of the process to get approval from the FDA for marketing a new prescription drug in the U.S. It makes promising new drugs available to desperately ill participants as early in the drug development process as possible. Treatment INDs are made available to participants before general marketing begins, typically during Phase III studies. To be considered for a treatment IND a participant cannot be eligible to be in the definitive clinical trial.

treatment trials: Refers to trials which test new treatments, new combinations of drugs, or new approaches to surgery or radiation therapy.

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V
Vaccine: a preparation that stimulates an immune response that can prevent an infection or create resistance to an infection.

Vaccinia: a cowpox virus, formerly used in human smallpox vaccines. Employed as a vector in HIV vaccines to transport HIV genes into the body.

Vector: in vaccine research, a bacterium or virus that does not cause disease in humans and is used in genetically engineered vaccines to transport genes coding for antigens into the body to induce an immune response. (See also vaccinia and canarypox.)

viral load: Measures the amount of new HIV produced and released into a person’s bloodstream. [See Reading Test Results]

Viremia: the presence of virus in the bloodstream.

Virus: a microorganism composed of a piece of genetic material : RNA or DNA : surrounded by a protein coat. To replicate, a virus must infect a cell and direct its cellular machinery to produce new viruses.
 

W
Western blot: a blood test to detect antibodies to several specific components of a virus such as HIV. This test is most often used to confirm a positive ELISA.

window period: The ‘window period’ is period between an exposure and the time it can take to develop antibodies. If you take a HIV test during the "window period” the results may not be a true reflection of your HIV status.

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