Research Initiative Treatment Action (RITA!); Vol 8, No. 2 Spring 2003

Adaptive: when referring to immunity, the cellular response involving lymphocytes and the establishment of immune memory.

Adenovirus: a type of DNA-based virus.

Adjuvant: a substance that improves the immune response to an antigen (see below).

Albumin: a common protein found in many animal tissues (eg, blood, muscle, etc.)

Antigen: a substance (usually a protein or carbohydrate, such as from an invading bacterium or virus) that stimulates an immune response.

Apoptotic (apoptosis): referring to genetically "programmed" cell death, a natural process in which DNA-damaged or otherwise unwanted cells are eliminated.

Astrocyte: a star-shaped cell found in the brain that protects and maintains neurons.

Aviremic: without active viremia; having a low or "undetectable" viral load.

Capsid: the protein coating or shell of a virus, which surrounds its nucleic acid (see below).

Cation: an ion (charged particle) with a positive charge.

cDNA: abbreviation for "complementary DNA," which matches a given RNA that serves as a template for synthesis of the DNA in the presence of reverse transcriptase.

Chemokine: a type of cytokine (see below) that can direct the movement of white blood cells to sites of inflammation in the body.

Chimeric: having a mixed genetic composition; a genetic cross.

Clade: A subtype of HIV made up of a group of related HIV isolates classified according to their degree of genetic similarity (such as the percentage of identity within their envelope genes). There are currently 3 groups of HIV-1 isolates M, N, and O. Isolate M (major strains) consists of at least 10 clades, A through J. Group O (outer strains) may consist of a similar number of clades.

Clone: a line of genetically identical cells, usually created or expanded from a single parent cell.

Codon: a specific sequence of 3 nucleotides (nucleic acid building blocks) that is part of a genetic code and denotes a particular amino acid in a protein chain; the sequence may also start or stop protein synthesis.

Cytokine: proteins (such as interleukins, tumor necrosis factor, and interferons) that are secreted by immune cells.

Dendritic cell: an antigen-presenting cell with long, branching extensions or processes.

Encephalopathy: disease of the brain, especially involving structural alterations.

Env: an HIV gene that encodes the 2 major viral glycoproteins (gp120 and gp41), which are associated with the viral envelope and are involved in viral attachment.

Epitope: a specific area on the surface of an antigen (see above) that can cause an immune response and can bind with a specific antibody produced by the immune system.

Gag: an HIV gene that codes for the p55 core protein, which is the precursor of the HIV proteins p6, p7, p17, and p24. These form HIV's capsid (see above).

HLA: human leukocyte antigens, which are marker molecules on the surface of cells that identify cells as "self" and prevent the immune system from attacking them.

Homozygous: having 2 identical copies of a particular gene (eg, each coding for the same particular trait, like blue eyes).

HTLV: a type of retrovirus (related to HIV) known as "human T-cell lymphotropic virus."

Humoral: part of the immune response that involves antibodies secreted by B lymphocytes (see below) and circulating in body fluids such as blood or lymph.

Idiopathic: happening suddenly or from an unclear or unknown cause.

Immunogenicity: an ability to produce an immune response.

Innate: when referring to immunity, the local barriers to infection such as skin, stomach acid, mucous, enzymes in tears and saliva, etc.

Intranasal: administered or introduced in the nose.

Intraperitoneal: administered or introduced in the peritoneum (abdomen).

Ligand: a molecule that forms part of a complex.

Lymphocyte: type of immune cell that originates from stem cells and differentiates in lymphoid tissue (such as the thymus or bone marrow); lymphocytes comprise 20% to 30% of the white blood cells in human blood.

Lymphocytopenia: a decrease in the number of lymphocytes (see above) in the blood.

Macrophage: a cell of monocyte-origin that can be stationary or mobile in the body and protects against infection by engulfing (phagocytizing) foreign substances, dead cells, etc.

Microbicide: a substance that kills microbes such as bacteria and viruses.

Microglia: a cell of the central nervous system that helps maintain and protect neurons.

Media: a liquid nutrient environment used in cell cultures.

Monochromosomal: having only a single human chromosome.

Mucosal: involving the tissues that line body cavities, tracts, and passages (like the nose, genital tract, etc.) that function in immune protection, nutrient absorption, and secretion of mucus, enzymes, etc. The mucosa often induces or initiates immune responses against certain antigens and can be a site for administering some vaccines.

Multivalent: effective or active against more than one antigen (see above).

Nef: an HIV regulatory gene that plays a major role in viral pathogenesis; the Nef protein has numerous effects including protecting infected host cells from apoptosis (see above) and altering cell receptor expression and distribution.

Neutralizing antibody: a type of protein produced by B lymphocytes (see above) after stimulation by an antigen; such proteins bind to specific antigens in an immune response and usually counteract or inactivate antigens.

Nucleocapsid: the nucleic acid (see above) and protein coat (capsid) of a virus.

Nucleic acid: DNA or RNA (ie, genetic material made up of building blocks known as nucleotides).

Open reading frame: a reading frame in a genetic sequence that does not contain a signal to stop protein translation (see below) before creating a complete protein.

Pathogenesis: the beginning and development of a disease.

Plasmid: a ring of DNA that replicates on its own and is usually found in bacteria; plasmids can be used to transfect (see below) cells with desired genes.

Pneumonitis: a disease that causes inflammation of the lungs.

Pol: An HIV gene that encodes the viral enzymes protease, reverse transcriptase, and integrase.

Primary: originating in or taken from humans (when referring to cells).

Proteasome: a structure in cells where damaged or unneeded proteins are broken down.

Supernatant: a usually clear liquid left after material (like cells) has been precipitated or centrifuged.

TAR: transactivation response element of HIV RNA located at the 5' end of all viral transcripts.

Tat: An HIV regulatory gene that is believed to enhance virus replication.

Th-1: a collection of cytokines (see above) that lead specific immune fighting cells to target viruses at the intracellular level.

Th-2: a collection of cytokines (see above) that lead specific immune fighting cells to target bacteria at the extracellular level.

Transduce (transduction): referring to the transfer of genetic material from one organism to another by a genetic vector, such as a virus or plasmid (see above).

Transfect (transfection): referring to the introduction and incorporation of outside DNA (eg, from a virus) into a cell.

Transgene (transgenic, transgenesis): referring to an artifical process whereby a gene is taken from one organism and introduced into the genetic make-up of another organism.

Transcription: a cellular process that makes a messenger RNA molecule using a DNA molecule as a template.

Translation: a cellular process accomplished at special structures known as ribosomes that make a protein molecule from information contained in messenger RNA.

Tropism (tropic): affinity or specificity for a particular target or stimulus.

Ubiquitin: a cellular protein that marks other proteins in the cell for degradation.

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Copyright © 2003 - Research Initiative Treatment Action (RITA!). Reproduced with permission. RITA! is published by The Center for AIDS. Contact Thomas Gegeny, MS, ELS, Editor, RITA! for permission to reproduce RITA!. tom@centerforaids.org. http://www.centerforaids.org

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