a nucleoside reverse transcriptase inhibitor drug approved for use as part of a combination regimen to treat HIV disease.

a set of FDA regulations governing early marketing approval of promising drugs for life-threatening illnesses.

the late stage of HIV disease; AIDS involves the loss of function of the immune system as CD4 cells are infected and destroyed, allowing the body to succumb to opportunistic diseases and cancers. The CDC defines AIDS as a CD4 cell count below 200 cells/mm 3 or the presence of at least one opportunistic illness in an HIV positive individual.

a nucleotide reverse transcriptase inhibitor that was unsuccessfully tested as an anti-HIV therapy, but is approved to treat chronic hepatitis B

a protease inhibitor drug approved for use as part of combination antiretroviral therapy to treat HIV disease.

a protein secreted by activated plasma cells, which evolve from B cells; antibodies are produced in response to foreign antigens as part of the body’s defense against disease. Specific antibodies bind to matching antigens; the antigen/antibody reaction forms the basis of humoral (Th2) immunity.

an agent that suppresses the activity or replication of retroviruses such as HIV by interfering with various stages of the viral life cycle; the four approved classes are nucleoside and nucleotide reverse transcriptase inhibitors (e.g., AZT, tenofovir), non-nucleoside reverse transcriptase inhibitors (e.g., efavirenz), protease inhibitors (e.g., ritonavir), and entry inhibitors (T-20)

any drug or other agent that interferes with the life cycle of a virus and suppresses its replication and/or pathogenic activity.

an immune system white blood cell that mediates the humoral (Th2) immune response; B cells are produced in the bone marrow and mature into plasma cells, which produce antibodies.

an initial or known value (e.g., CD4 cell count, HIV viral load) against which later measurements can be compared

a condition caused by a Candida fungus, usually C. albicans . Candidiasis may affect the skin, nails, and mucous membranes throughout the body including the mouth, esophagus, and vagina; oral or vaginal candidiasis may be an early sign of immune impairment in people with HIV

a protein marker on the surface of certain types of T lymphocytes and other cells; HIV binds to CD4 receptors to enter host cells.

a type of white blood cell that bears the CD4 surface receptor and helps coordinate a range of immune system activities. HIV impairs immune function by attacking and killing CD4 cells.

the absolute number of CD4 cells in one cubic millimeter (mm 3) of blood. The CD4 cell count is one indicator of HIV disease progression. A normal CD4 cell count ranges from about 600 to 1,200 cells/mm 3; moderate immunosuppression in adults is associated with a CD4 cell count between 200 and 500 cells/ mm 3, while severe immunodeficiency is associated with counts below 200 cells/ mm 3. Current U.S. federal guidelines recommend treatment when the CD4 cell count falls below 350 cells/ mm 3.

the number of CD4 cells as a proportion of the total number of lymphocytes; a normal CD4 cell percentage is 30-60%. CD4 cell percentage is a more consistent and reliable measure than absolute CD4 cell count.

the ratio of CD4 cells to CD8 cells; a normal CD4/CD8 ratio is 0.9-3.0.

a type of white blood cell that bears the CD8 cell surface marker and helps regulate or carry out the body's immune responses. The two subsets of T cells that express the CD8 marker are suppressor T cells and cytotoxic T lymphocytes (CTLs, or killer T cells). A normal CD8 cell count is 200-1,000 cells/ mm 3, and a normal CD8 cell percentage is 15-40%.

the basic unit of living organisms; a typical animal cell contains a nucleus and a cell membrane surrounding the intracellular material, or cytoplasm.

a soluble substance that inhibits HIV replication in infected cells; the precise identity of this factor is not known.

a specific type of cell that is maintained in vitro for medical or research purposes.

the envelope surrounding an animal cell that encloses the cytoplasm and controls the movement of substances into and out of the cell.

a type of immune response coordinated by certain CD4 cells and carried out by cytotoxic T lymphocytes, activated macrophages, and natural killer cells. Cell-mediated immunity is particularly effective against virus-infected and cancerous cells

the U.S. federal government agency within the Department of Health and Human Services that monitors disease occurrence and develops policies for preventing diseases and maintaining the health of the population.

a red, painless ulcer; a primary sore or lesion that forms at the site of entry of a microorganism (e.g., the spirochete bacterium that causes syphilis).

one of a family of soluble substances secreted by cells that act as chemical messengers, stimulating or inhibiting the activity of other cells.

a sequence of three nucleotides that encodes the information for a particular amino acid; mutations at specific codon locations can confer resistance to certain drugs.

a system of enzymes (e.g., CYP3A4) that metabolize many drugs in the liver; drug interactions may occur when one agent induces or inhibits CYP450 activity, thus speeding up or slowing down the metabolism of other drugs.

an intercellular hormone produced by immune cells that acts as a chemical messenger to facilitate communication among immune cells and between immune cells and the rest of the body; cytokines (e.g., interferon, interleukins, tumor necrosis factor) coordinate and regulate many aspects of immune response, including antibody production, migration of phagocytes, and activation of cytotoxic T lymphocytes.

the study of the structure, function, and pathology of cells.

destruction of a cell by rupturing.

a type of white blood cell that bears the CD8 surface marker, and targets and kills cancerous cells and cells infected with viruses; the action of CTLs is coordinated by CD4 cells via the production of cytokines

a nucleoside reverse transcriptase inhibitor drug approved for use as part of combination antiretroviral therapy to treat HIV disease.

a nucleoside reverse transcriptase inhibitor drug approved for use as part of combination antiretroviral therapy to treat HIV disease.

a nucleoside reverse transcriptase inhibitor drug approved for use as part of combination antiretroviral therapy to treat HIV disease.

the rate at which an amount (e.g., HIV viral load) declines over time.

a non-nucleoside reverse transcriptase inhibitor drug approved for use as part of combination antiretroviral therapy to treat HIV disease.

a molecule found in the nucleus of cells as a twisted double-stranded chain (double helix) that encodes genetic information; the particular sequence of four chemical building blocks (nucleotides) that make up a DNA chain -- adenine, cytosine, guanine, and thymine -- determines an individual’s unique genetic makeup.

a non-nucleoside reverse transcriptase inhibitor drug approved for use as part of combination antiretroviral therapy to treat HIV disease.

factors used to determine whether a person is eligible to participate in a clinical trial; inclusion criteria are conditions a potential participant must meet in order to be eligible (e.g., a certain CD4 cell count or viral load), while exclusion criteria are conditions that disqualify a person from participating (e.g., pregnancy, opportunistic illnesses).

a drug (e.g., T-20 [enfuvirtide, Fuzeon]) that prevents HIV from entering cells. Entry inhibitors work by a variety of methods, including fusion inhibitors, which prevent HIV from fusing with a cell membrane, and coreceptor (CCR5 and CXCR4) blockers, which prevent HIV from binding with coreceptors needed for cell entry.

the HIV gene that encodes the proteins of the viral envelope; also refers to the protein (Env) produced by this gene.

the outer covering of some viruses. The HIV envelope is composed of two protein subunits, gp120 and gp41, encoded by the env gene; the gp120 glycoprotein attaches to the CD4 surface proteins, allowing HIV to enter cells.

a protein that catalyzes (induces or accelerates) a chemical reaction.

a laboratory test used to detect the presence of antibodies in the serum. The ELISA is used to screen for HIV infection; a positive result indicates that antibodies are present.

a granulocyte (a type of white blood cell) that plays a role in allergic reactions and defense against parasites; eosinophilia refers to an elevated level of eosinophils in the blood.

an outbreak of a disease within a population.

the study of the frequency, distribution, and behavior of a disease within a population.

a protease inhibitor drug approved for use as part of combination antiretroviral therapy to treat HIV disease; fosamprenavir is a prodrug of amprenavir that reaches higher therapeutic drug levels in the body.

a nucleoside reverse transcriptase inhibitor drug approved for use as part of combination antiretroviral therapy to treat HIV disease.

refers to an unusually severe or aggressive form of a disease.

a sexually transmitted infection caused by the bacteria Neisseria gonorrhoeae . Gonorrhea may be asymptomatic or may include symptoms such as urethritis, discharge, pelvic pain, and inflammation of the tissues of the genitals, rectum, and/or throat; untreated gonorrhea may spread to the upper genital tract and lead to pelvic inflammatory disease (PID) in women.

an agent that blocks the action of the helicase enzyme.

disease or illness caused by infection with the human immunodeficiency virus; if untreated, the disease typically progress slowly from asymptomatic infection to worsening immunocompromise to full-blown AIDS.

a slow-acting blood-borne retrovirus of the lentivirus family, believed to be the sole or primary cause of AIDS. There are two major types, HIV-1 and HIV-2, and many subtypes of the virus. HIV-1 is prevalent throughout most of the world; HIV-2 is found mostly in West Africa and typically causes a milder form of immunodeficiency disease.

clusters that are formed when antigens and antibodies bind together

a breakdown or failure of certain parts of the immune system to function at all, thus making a person susceptible to certain diseases that they would ordinarily not develop.

the body's intricate natural defense against disruption caused by invading foreign agents (e.g., microbes, viruses); the creation of cloned populations of antibody-producing B cells and cytotoxic T lymphocytes primed to respond to a unique pathogen is the body’s way of combating infection.

any substance that influences the immune system.

a bodily state in which the immune system is damaged and fails to perform its normal functions. Immunosuppression may be induced by drugs (e.g. in chemotherapy) or result from certain disease processes, such as HIV.

a plant or animal toxin (i.e., poison) that is adhered to a monoclonal antibody and utilized to destroy a specific target cell

an HIV enzyme used by the virus to integrate its genetic material into the host cell's DNA.

that which relates to the inside of a vein, as of a thrombus, or an injection, infusion or catheter.

a previously uncommon form of cancer that attacks the connective tissue, bones, cartilage and muscles of the body. The cancer may spread and also attack the eyes. If the cancerous area is near the surface of the skin, lesions inches in length may develop. Radiotherapy and chemotherapy are usually recommended

killer cells infected with HIV or other viruses or transformed by cancer. Also known as cytotoxic T cells, or cytotoxic T lymphocytes.

specialized macrophages in the liver

a group of closely related HIV isolates that includes the LAV, IIIB and BRU strains of HIV. They are used in HIV vaccine development.

all white blood cells.

a decrease in the number of white blood cells. The threshold value for leukopenia is usually taken as less than 5000 white blood cells per cubic millimeter of blood.

individuals, who are HIV-infected for seven or more years, have stable CD4+ T cell counts of 600 or more cells per cubic millimeter of blood, no HIV-related diseases and no previous antiretroviral therapy. Data suggest that this phenomenon is associated with the maintenance of the integrity of the lymphoid tissues and with less virus trapping in the lymph nodes than seen in other HIV-infected individuals.

the rupture and destruction of a cell.

a massive immune cell that preys on invading pathogens and other intruders. It stimulates other immune cells by presenting them with small pieces of the virus or invader. Macrophages can store large quantities of HIV without being killed, acting as reservoirs of the virus.

a category of T lymphocytes that have been exposed to specific antigens and can then proliferate (i.e., reproduce) on subsequent immune system encounters with the same antigen

known as mRNA. An RNA (ribonucleic acid) that carries the genetic code for a particular protein from the nuclear DNA (i.e., the DNA in the cell's nucleus) to a ribosome in the cytoplasm and acts as a template, or pattern, for the formation of that protein.

the minutest particle of a compound that has all the chemical properties of that compound. Molecules are comprised of two or more atoms, either of the same element or of two or more different elements.

antibodies manufactured by a hybridoma or antibody-producing cell source for a specific antigen. Monoclonal antibodies are useful as a tool for identifying specific protein molecules.

a large white blood cell that ingests microbes or other cells and foreign particles. When a monocyte enters tissues, it develops into a macrophage.

a vaccine that is specific for only one antigen

an opportunistic bacterial infection that can be limited to a specific organ or area of the body, or disseminated throughout the body. It is a life-threatening disease, although new therapies offer promise for both prevention and treatment.

a type of lymphocyte that does not carry the markers to be B cells or T cells. Like cytotoxic T cells, they attack and kill tumor cells and protect against a wide variety of infectious microbes. They do not need additional stimulation or need to recognize a specific antigen in order to attack. Persons with an immunodeficiency such as those caused by HIV infection have a decrease in "natural" killer cell activity.

one of the HIV regulatory genes. Three HIV regulatory genes-tat, rev and nef-and three so-called auxiliary genes-vif, vpr and vpu-contain information necessary for the production of proteins that control the virus's ability to infect a cell, produce new copies of the virus or cause disease.

the procedure by which an antibody binds to specific antigens, thereby "neutralizing" the microorganism.

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

also called polymorphonuclear neutrophil (PMN). A white blood cell that plays a central role in defense of a host against infection. Neutrophils engulf and kill foreign microorganisms.

nucleosides are related to nucleotides, the subunits of nucleic acids; however, they do not carry the phosphate groups of the nucleotides.

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. Opportunistic infections common in AIDS patients include Pneumocystis carinii pneumonia, Kaposi's sarcoma, and shigellosis.

a disease occurring throughout an entire country, continent or globally.

any disease-producing microorganism or material.

the origin and development of a disease.

a cell that is able to taken in and eliminate foreign matter, including bacteria.

the process of ingesting and destroying a virus or other foreign matter by phagocyte.

large antibody producing cells that spawn from B cells.

a life-threatening lung infection that can affect people with weakened immune systems, such as those infected with HIV. More than three-quarters of all people with HIV disease are bound to develop PCP if they do not receive treatment to prevent it. The standard treatment for people with PCP is either a combination of trimethoprim and sulfamethoxazole

a measure of the ratio of people in a population afflicted by a particular disease at a given time.

treatment that helps to prevent a disease or condition before it occurs or recurs.

HIV protease is an enzyme essential to the reproductive life cycle of HIV. The three-dimensional molecular structure of the HIV protease has been fully determined. Pharmaceutical developers are therefore able to logically create compounds to hinder it and thus interfere with replication of the virus

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

three regulatory HIV genes --tat, rev and nef-- and three so-called auxiliary genes --vif, vpr and vpu-- contain information for the production of proteins that control (i.e., regulate) the virus's ability to infect a cell, produce new copies of the virus or cause disease.

HIV and other viruses that carry their genetic material in the form of RNA and that have the enzyme reverse transcriptase. Like all viruses, HIV can replicate only inside cells, commandeering the cell's machinery to reproduce. Like other retroviruses, HIV uses the enzyme called reverse transcriptase to convert its RNA into DNA, which is then integrated into the host cell DNA.

the enzyme of the HIV that converts the single-stranded viral RNA into DNA, the form in which the cell carries its genes. The antiviral drugs approved in the US for the treatment of HIV infection all work by interfering with this stage of the viral life cycle.

the creation of antibodies to a particular antigen. When people develop antibodies to HIV or an experimental HIV vaccine, they "seroconvert" from antibody-negative to antibody-positive.

a contagious disease usually acquired by sexual intercourse or genital contact. Historically, the six venereal diseases were: gonorrhea, syphilis, chancroid, granuloma inguinale lymphogranuloma venereum, and AIDS.

the action or effect of a drug other than that desired. The term usually refers to undesired or negative physical effects, such as headache, skin irritation or liver damage, experienced after drug consumption. Experimental drugs must be evaluated for both immediate and long-term side effects.

a genetically engineered vaccine that is based on only part of the HIV molecule.

investigators have proposed that a molecule known as a superantigen, either produced by HIV or an unrelated agent, stimulates massive quantities of CD4+ T cells at once, rendering them highly susceptible to HIV infection and subsequent cell death.

subset of T cells that inhibit antibody production and other immune responses

a thymus-derived white blood cell that participates in a variety of cell-mediated immune reactions. Three fundamentally different types of T cells are recognized: helper, killer and suppressor (each has many subdivisions).

the procedure by which HIV messenger RNA is developed in a cell's nucleus and transported to the cytoplasm, the cellular material outside the nucleus.

HIV is spread most commonly by sexual contact with an infected partner. The virus can enter the body through the mucosal lining of the vagina, vulva, penis, rectum or, very rarely, the mouth during sex.

a hollow muscular organ located in the pelvic cavity of female mammals in which the fertilized egg implants and develops.

section of a protein on the surface of HIV. Appears to be important in stimulating neutralizing antibodies

a substance that contains antigenic components from an infectious organism by stimulating an immune response. It protects against subsequent infection by that organism.

HIV is spherical in shape with a diameter of 1/10,000 of a millimeter. The outer coat, or envelope, is composed of two layers of fat-like molecules called lipids, taken from the membranes of human cells.

any agent that destroys or inactivates a virus.

an organism, that during its stage of the life cycle when they are free and infectious, carries out the usual functions of living cells, such as respiration and growth; however, makes use of another plant or animal cell to carry out functions such as protein synthesis and nucleic acid replication.