Acute infection - shows their symptoms immediately and dissipates quickly.


Amino acid - organic nitrogenous compounds that act as the structure of proteins and are synthesized or obtained by cells as a regular diet.


Antibody - proteins created in blood and tissue by the immune system to help neutralize and destroy possible threats.


Antigen - a toxin or enzyme which stimulates reactions from a body's immune system.


Antigenicity - The ability of an antigen to combine with antibodies and T-cell receptors to invoke a reaction from the immune system.


Autoimmune diseases diseases caused when the immune system turns on itself because it fails to recognize its own cells.


B lymphocyte cells - bursa-dependent; manufactured in the bone; identify antigens and produce antibodies.


Bacteriophages - viruses that infect and kill harmful bacteria.


Base pair - a twin pair of nucleotides contained in a nucleic acid strand, which are linked together by hydrogen bonds.


Body fluids - fluids of the body, including circulating blood and lymph, the chyle, the gastric, pancreatic, and intestinal juices, the saliva, bile, urine, aqueous humor, and muscle serum


Budding - mature viruses leave a cell slowly, a few at a time, not killing the host cell in the process.


Bursa - a tissue space lined by joint tissue; bursas are found in between tendon and bone, skin and bone and muscles.


Carrier - one who carries a virus either in form of an infection or while it is in incubation.


Caspid - The protein outer covering of a virus made up of capsomeres; stimulates the body's immune response.


Cell - a small, enclosed unit containing the DNA, proteins, and chemicals needed for all life functions.


Chromosomes - a DNA containing body that holds most or all of the genes of an individual life form.


Chronic infection - recurring viral infections that cause damage of cells over a long period of time by disrupting their functions.


CNS - the central nervous system, which is comprised of nerves, the brain and the spinal cord.


Connective tissue - tissue that surrounds other more highly ordered tissues and organs; blood, cartilage and bone.


Cytoskeleton - protein filaments that extend through the cytoplasm of cells and enable them to move and change shape.


DNA - deoxyribonucleic acid, the basic component of all living matter, which is contained in the chromosomes of a cell's nucleus; transmits hereditary information and contains gene sequences.


Differentiated - a type of cell, which specializes in one specific task or has one specific purpose.


Dormant - being in a state of suspended animation, not actively growing but protected from the environment.


Electron Microscopy - an imaging method, which uses a focused beam of electrons to enlarge the image of an object on a screen or photographic plate.


Endocytosis - the process in which cells take in fluids or other large molecules.


Enzyme - a type of protein, which catalyzes the reactions between substrates (substances).


Filovirus - The thread-like virus family which includes such viruses as Ebola and Marburg; very deadly.


Genes - a sequence of DNA or RNA that is located on a chromosome and that is the functional unit of inheritance controlling the transmission of traits and function of other genetic material.


Glycoprotein - a compound produced by mixing a protein with any member of a carbohydrate group.


Helper T cells - coordinate the actual immune response of the body; they let other T cells and B cells do their jobs.


Hemorrhagic fever - a condition characterized by non-stop internal or external bleeding resulting from a viral infection which has caused blood vessel damage.


Hereditary material - material responsible for the transmission of qualities from ancestor to descendant through genes.


Host - a living organism, which provides subsistence or lodgment to a parasite.


Humoral immune response - the immune responses mediated by antibodies.


Inactivated vaccine - dead microorganisms used as antigens to produce immunity.


Inclusion bodies - strange and unusual structures found inside a host cell during virus replication.


Infection - the state produced by the presence of an infective agent in or on a suitable host.


Immune System - A body function designed to defend the body from disease causing microorganisms.


Immunity - the condition of being immune, the protection against infectious disease.


Latent infection - viral infection in which the virus responsible is able to avoid the hosts immune system and defenses.


Leukocytes - the majority of the specialized cells used in the immune system; white blood cells.


Lipid - a fatty and oily compound used by cells as energy reserves and material for structure.


Lymph nodes - small bean-shaped organ made up large numbers of lymphocytes, macrophages and accessory cells located along the lymphatic system


Lymphoid tissue - tissue made up white blood cells and special fibers.


Lysis - the cell membrane of a host is completely destroyed and newly replicated viruses are unleashed instantaneously.


Macrophage - contains lysosomes full of special enzymes and chemicals, which allows it to ingest and digest dangerous microbes


Memory cells - keep the body prepared for the next struggle with antigens that have already been encountered.


mRNA (messenger RNA) - used as the carrier of genetic codes and information directly from DNA to cell structures.


Mutation - a rearrangement of genes or change in base pairs so they produce different effects within their environment.


Nanometer - One-millionth of a millimeter.


Nucleic acid - an organic compound made up of a phosphoric acid, a carbohydrate and a base of purine or pyrimidine; formed in helical chains.


Nucleus - a cellular organelle that is the essential control mechanism for cell function; contains the DNA and genetic material.


Origin - location where the process of replication in a nucleic acid begins.


Parasite - an organism living in or on another organism that depends on its host for existence or support and gives nothing in return.


Pathogenesis - the growth and development of a disease.



Prion - an infectious crystallizing protein, which affects the brain.


Proteins - strands of amino acids which make the enzymes and structures needed for cells to grow and function properly.


RNA (ribonucleic acid) - strings of organic material, obtained from DNA, which store the proper instructions necessary to produce amino acids.


Receptor - a structure on a cell which joins with proteins to produce changes in cellular function.


Replication - the action or process of reproducing exact copies of one's self.


Retrovirus - An RNA virus that converts its RNA into DNA by means of the enzyme reverse transcriptase and integrates itself directly into the host's DNA.


Reverse transciptase - special enzyme which allows retroviruses to translate genetic code from RNA to DNA.


Ribosome - the spherical structure that assembles proteins after being fed the genetic instructions by mRNA.


Spleen - an organ that produces lymphocytes, filters the blood, and stores blood cells


Strain - a specific type, quality, or disposition of a material.


Suppressor T cells - monitor and adjust antibody levels in the body; act as suppressors to counteract the Helper and Killer T cells at the end of infections.


Thymus - The lymphoid organ in which T lymphocytes are educated, mature and multiply.


T lymphocyte cells - thymus dependent cells, coordinate the cell-mediated immune system.


Transcription - constructing a mRNA molecule using a DNA molecule as a template; results in the transfer of genetic information to the mRNA.


Vaccine - Weakened or destroyed microorganisms used to help provide immunity to a certain disease or microorganism and to stimulate the production of antibodies.


Variant - a variation of a particular strain of virus or infective agent; slightly different in form or function.


Vector - anything capable of moving or transferring genetic material.


Viroid - exotic type of virus which only infects plant cells and is simply a group of naked strings of amino acids with no covering.


Virus - infectious organism that replicates itself in the cells of a host; viruses have a half alive/half dead existence and need a host to grow and reproduce.