Cumulative Glossary

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A

Adjuvants:

Substances or chemical formulations used to enhance the immune response to inactivated vaccines. They act by retaining the immunogen at the injection site, as by a depot effect, and thus delaying its release; the antigenic stimulation is prolonged and consequently increased. Some adjuvants may also stimulate macrophages, lymphocytes and other cells involved in the immune response. Salts of metals, such as those of aluminum, oil emulsions (Freund's adjuvants), and synthetic lipid vesicles (liposomes) are some of the adjuvants used. - View Chapter -

Aliquoted:

Divided (as a solution) into equal parts. - View Chapter -

Alternative Complement Pathway:

Pathway of complement activation by which complement component C3 is cleaved and C5-C9 formed without a requirement for C1, C2 or C4. It does not require antibody. - View Chapter -

Antigen:

A substance, usually external to the body but occasionally within the body, which the immune system recognizes as foreign or non-self. When thus recognized it elicits a specific antibody which reacts with it.

Antigen-antibody Complex:

It is a macromolecular complex of antigen and antibody bound together specifically. Also called immune complex. - View Chapter -

Antigen-capture/trapping ELISA:

In this method, specific antibody is used to bind (or trap) any viral antigen that may be present in the sample. Presence of any trapped antigen is then detected. - View Chapter -

Aplastic Anemia:

An anemia in which the bone marrow fails to produce sufficient numbers of blood elements. - View Chapter -

Apoptosis:

A form of programmed cell death characterized by the fragmentation of nuclear DNA. - View Chapter -

Ambisense:

Refers to an RNA genome containing sequence information that is both-positive sense (can be used directly as mRNA) and negative-sense (must be transcribed to form mRNA). - View Chapter -

Arbovirus:

Any virus of vertebrates that is transmitted via arthropods. - View Chapter -

Arthrogryposis:

Permanent flexure of a joint. - View Chapter -

B

Bacteriophage:

A virus that infects prokaryotic cells and has many of the attributes of animal and plant viruses. It requires a living bacterium to carryout its reproductive cycle. - View Chapter -

BCG Vaccine:

BCG stands for Bacille Calmette-Guérin. It is a vaccine to prevent tuberculosis prepared from an attenuated strain of Mycobacterium bovis - View Chapter -

Budding:

In this process enveloped viruses acquire their envelope. It is preceded by insertion of virus-specific glycoproteins into host cell membranes. Budding occurs most frequently at the plasma membrane and confers infectivity. - View Chapter -

Bursa of Fabricius:

This sac-like lympho-epithelial structure, unique to birds, is associated with the cloaca. Maturation of of B lymphocytes takes place in this organ. - View Chapter -

C

Capture ELISA:

In this method, specific antibody is used to bind any viral antigen that may be present in the sample. Presence of any bound antigen is then detected spectrophotometrically using a labeled antibody specific for the antigen, following addition of the enzyme substrate.nbsp;- View Chapter -

Classical Complement Pathway:

This is a series of sequential enzyme-substrate interactions activated by antigen-antibody complexes and involving all of the C components. - View Chapter -

Combined Immunodeficiency:

Total absence T and B lymphocytes; an autosomal recessive inheritance pattern. In EAV-A, the combined immunodeficiency is characterized by progressive EAV-A bronchopneumonia, and pathology in a wide variety of organs and tissues, including the gastrointestinal tract, liver, pancreas and bladder. - View Chapter -

Competitive ELISA:

Antigen and the competitive substance (analog) will compete for specific antibodies. Concentration can be determined by comparison of the blocking effect (competition) by standardizing the concentrations of analog and antibody. - View Chapter -

Conservative Replication:

Replication of dsDNA or dsRNA in such a manner that the original strands do not become a part of the newly formed progeny dsDNA or dsRNA. - View Chapter -

Counterimmunoelectrophoresis:

The detection of antigen or antibody by a precipitin reaction that occurs in a gel or paper. An electric current is used to move the reactants toward each other. - View Chapter -

Cynomologus Monkeys:

From southeastern Asia, Borneo and the Philippines. Rhesus monkeys are from India. - View Chapter -

Cytokines:

A diverse group of small (< 30 kilodalton), soluble proteins produced by leukocytes that mediate a variety of immune functions. - View Chapter -

Soluble molecules that mediate interactions between cells. - View Chapter -

Cytopathic Viruses:

These are viruses that alter the microscopic appearances of cells in culture. The changes may include rounding up of cells, cell fusion, cell detachment, production of inclusion bodies, etc. - View Chapter -

Cytotoxic T Lymphocytes:

Cells that recognize foreign antigens imbedded in MHC class I molecules. They are only effective in killing cells containing foreign antigen. - View Chapter -

D

Density Gradients:

This is a procedure for separating cells or large molecules, such as proteins and nucleic acids, usually by centrifugation through a density gradient. The latter consists of a solution in which there is a range of densities with the solute (generally sucrose or cesium chloride) less concentrated at the top and more concentrated at the bottom. As a result of centrifugation the cells or molecules move through the gradient and form a band at the density where their specific gravity is equal to that of the medium. - View Chapter -

Dot-blot Hybridization:

A diagnostic procedure in which the material to be examined is blotted directly on to a membrane (frequently nitrocellulose) then hybridized with reference probes prepared from virus-specific DNA. The probes are labeled (chemically or radioactively) and a signal is detected where hybridization occurs. - View Chapter -

Dystrophic:

Maldevelopment caused by or related to faulty nutrition. - View Chapter -

E

Endocytic Vesicle:

A vesicle formed in the process of endocytosis, the "engulfment" of the virus, which can be mediated by surface receptors or cell membrane interactions. - View Chapter -

Endosymbiontic:

Form of symbiosis where one organism lives within another. - View Chapter -

Exocystosis:

A process by which a variety of substances are released from the cell within vesicles by transport to and fusion with the plasma membrane, resulting in the release of the vesicle contents from the cell. - View Chapter -

F

Fas Protein:

A type 1 transmembrane protein of the TNFR (tumor necrosis factor receptor) superfamily. It is expressed on many cell types including those of the myeloid series. - View Chapter -

G

Genotype:

A virus genotype is based on partial or complete nucleotide sequence analysis. - View Chapter -

Golgi Membrane:

A membrane associated with the Golgi apparatus of a eukaryotic cell. The Golgi apparatus receives newly synthesized lipids and proteins from the endoplasmic reticulum and chemically modifies and traffics them to the appropriate locations in the cell. - View Chapter -

Granzymes:

A collection of serine proteases; they pass into the target cell via the transmembrane channels created by perforin, where they interact with the various intracellular pathways that trigger apoptosis and DNA degradation. - View Chapter -

H

Harderian gland:

An accessary lacrimal gland located on the inner side of the orbit in reptiles and birds. - View Chapter -

Hemagglutinin-esterase (HE) protein:

This protein causes hemagglutination of red blood cells and may also initiate binding to target cells. - View Chapter -

Hydranencephaly:

In this condition fluid-filled cavities take the place of the cerebral hemispheres. - View Chapter -

An abnormal increase in the amount of cerebrospinal fluid in the cranial cavity. It is accompanied by enlargement of the cerebral ventricles and skull with atrophy of the brain. - View Chapter -

I

Inclusion Bodies:

These represent virus "factories" in which viral nucleic acid or protein is being synthesized. - View Chapter -

Interferons:

Comprised of three different proteins designated alpha, beta, and gamma. All have a non-specific action against viruses, but alpha and beta are the more potent. - View Chapter -

Interleukins:

A group of cytokines secreted by effector cells of the immune system that effect responses by other immune cells. - View Chapter -

Interleukin (IL)-10:

Cytokine that can decrease immune response to viruses by inhibiting INF-γ production. - View Chapter -

K

Koilocytes:

These are epidermal cells in the superficial layers of the epidermis that have a swollen, glassy, highly eosinophilic cytoplasm. They contain papillomavirus. - View Chapter -

L

Lectins:

Plant glycoproteins that bind specifically to certain sugars, some of which occur on the surface of cells. - View Chapter -

Ligase:

A host enzyme that creates covalent bonds in nucleic acids associated with breaks in the sugar-phosphate backbone of the molecule. - View Chapter -

M

Macrophages:

The main phagocyte of tissues, organs and such serous membranes as the pleura and peritoneum. - View Chapter -

MHC Class I Antigens (major histocompatibility complex):

Collection of genes coding for the self-marking proteins or major irreconcilability antigens. These antigens occur on the surface of all body cells and serve to identify them as belonging to the body and not foreign. Some MHC antigens appear on the surface of cells of the immune system. The human MHC region is known as the HLA (human leukocyte antigen) region and is located on chromosome 6. - View Chapter -

Monocistronic:

Contains information for a single gene or gene product. - View Chapter -

Monopartite:

A viral genome having a single segment. - View Chapter -

Mucopolysaccharide:

A class of polysaccharides (glycosamineglycans) such as heparin, hyaluronic acid and chondroitin sulfate that bind water to form thick gelatinous, mucoid material. - View Chapter -

Multi-component Genomes:

Genomes having more than one nucleic acid molecule making up its total genome. - View Chapter -

Muscovy Duck:

Greenish-black, domesticated duck with heavy red wattles known around the world for its succulent flesh. - View Chapter -

Mutagens:

Chemical or physical agents that increase the mutation rate of the DNA of an organism. - View Chapter -

N

Natural Killer Cells (NK cells):

Cytotoxic lymphocytes, which comprise approximately 5 to 15% of circulating lymphocytes, lack the phenotypic markers of T and B cells. They have capacity to kill certain tumor cells and virus-infected cells that lack major histocompatibility (MHC) markers on cell surfaces and their mechanism of killing is similar to that of cytotoxic T cells. - View Chapter -

Negative-sense DNA:

DNA whose transcription does not produce an RNA molecule that can be used directly as mRNA. It is the template for creation of negative-sense RNA genomes. - View Chapter -

Nested PCR:

PCR performed twice with two different primer sets, the second "nested" within the region amplified by the first set. In this manner, very low levels of PCR product can be made in greater quantity. - View Chapter -

Neuraminidase:

A glycoprotein which is present as a spike on the outside of the influenza virus envelope. It breaks down an inhibitor of the influenza virus hemagglutinin protein. - View Chapter -

Neuropil:

A network of axons and dendrites of neuroglial cells in mainly the central nervous system. - View Chapter -

Neutrophils:

A short-lived phagocytic cell with granules that contain a number of bactericidal compounds; most numerous of the circulating leukocytes constituting approximately 60 to 70% in humans. Microscopically they have an irregularly shaped, multi-lobed nucleus; also called polymorphonuclear leukocytes. - View Chapter -

O

Oligosaccharide:

A sugar that contains a known small number of monosaccharide units. - View Chapter -

Oncogene:

A gene that encodes a protein whose expression leads to cell transformation and malignancy (changes in the cell including loss of contact inhibition, which leads to neoplastic potential).

Opsonin:

A substance that binds to particles including microorganisms and facilitates their phagocytosis. - View Chapter -

P

Palindromes:

Sequences that read the same in both directions. Most recognition sites of restriction endonucleases are palindromes, e.g., the recognition sequence of EcoRI (E. coli) is:

5' GAATTC 3'

3' CTTAAG 5'. - View Chapter -

Panophthalmitis:

Inflammation involving all the tissues of the eyeball. - View Chapter -

Peplomers:

Glycoprotein structures that protrude from the envelope surface; also known as spikes. - View Chapter -

Perforins:

A pore-forming protein that requires the presence of calcium in order to polymerize and form transmembrane channels in the plasma membrane of the target cell. - View Chapter -

Pinocytosis:

A cellular process that allows the entry of fluids into a cell by invagination of the cell membrane, followed by formation of vesicles within the cells.

Polyadenylation:

This is the addition of tracts of adenosine polymers to the 3N ends of messenger RNAs in eukaryotic cells. - View Chapter -

Polycistronic:

Contains information for several genes or gene products. - View Chapter -

Polymorphisms:

Refers to multiple alleles for a particular gene within a population. - View Chapter -

Positive-sense DNA:

DNA whose transcription produces the genome of positive-sense RNA genomes or can be used directly as mRNA. - View Chapter -

Primers:

These are short stretches of DNA or RNA used as starting points for nucleic acid synthesis. A primer hybridizes with a template strand of nucleic acid and provides a 3' hydroxyl end for the initiation of synthesis. The primers delimit the region that will be amplified. In PCR, two (sometimes more) synthetic oligonucleotide primers (about 20 nucleotides each) complementary to regions on opposite strands flank the target sequence; the 3' hydroxyl ends are oriented to each other. In PCR the target sequence in a sample is about 100 to 2000 bp in length. Designed primers and arbitrary ("off-the-shelf") primers are used. - View Chapter -

Probang:

A slender flexible rod with a sponge on one end used to collect clinical material. - View Chapter -

Proteinase K:

An endolytic serine protease that cleaves peptide bonds at the carboxylic sides of aliphatic, aromatic or hydrophobic amino acids. - View Chapter -

R

Real time PCR:

This type of PCR utilizes a chemical amplicon, such as SYBR green, that emits a fluorescent signal during the DNA replication. The emitted signal is detected and indicates active DNA replication prior to running an agarose gel. - View Chapter -

Reciprocal inhibition test:

A test in which inhibition titers, corresponding to the reciprocal of the last dilution that completely neutralize virus, are compared between various strains of the same virus. - View Chapter -

Regulatory Tests:

These are tests conducted under the auspices of official disease control agencies in the interest of controlling important infectious animal diseases. - View Chapter -

Restriction Endonucleases:

These are enzymes derived from bacteria that recognize and cleave specific DNA sequences. - View Chapter -

Restriction Fragment Length Polymorphism:

These reveal many differences in DNA sequences among individuals of a species. RFLPs result from cleavage of DNA by restriction enzymes (see above), separation of the fragments by gel electrophoresis and visualization of bands (DNA fragments) by staining with fluorescent ethidium bromide. - View Chapter -

Reverse Transcriptase:

A viral enzyme that uses a RNA template to synthesize DNA. - View Chapter -

Reverse-transcriptase PCR:

A modification of the polymerase chain reaction that includes a first step utilizing the enzyme reverse transcriptase, which makes a DNA copy of viral RNA template. The DNA is then amplified utilizing polymerase chain reaction. - View Chapter -

RT-PCR:

Real-time PCR is a technique where PCR is monitored spectrophotometrically during the PCR process. This method is very sensitive to the detection of product prior to agarose gel electrophoresis. - View Chapter -

S

S phase:

The stage of the cell cycle when DNA synthesis occurs. - View Chapter -

Semiconservative Replication:

Replication of dsDNA or dsRNA in such a manner that the original strands (one original, one newly synthesized) become a part of the newly formed progeny dsDNA or dsRNA. - View Chapter -

Seroconversion:

The development of demonstrable antibody in response to a disease or a vaccine. - View Chapter -

Shuttle Vector:

Any DNA molecule capable of autonomous replication within a host cell and into which other DNA sequences can be inserted. They are used for transporting foreign genes into recipient cells. - View Chapter -

Single-component Genomes:

Genomes having a single nucleic acid molecule making up its total genome. - View Chapter -

Synthetic Phase:

Refers to the initiation of transcription and translation, resulting in the production of new virion particles. - View Chapter -

T

Taq polymerase:

This is the DNA polymerase used in PCR. It is derived from the bacterium Thermus aquaticus that lives in hot springs; the polymerase's thermostability makes PCR possible. - View Chapter -

Tautomers:

These are isomeric forms of organic compounds and when two of them exist in equilibrium it is referred to as tautomerism. - View Chapter -

Transcriptase:

A viral enzyme capable of using an RNA molecule as a template for transcription. - View Chapter -

Transduction:

Transfer of host DNA genetic material from one cell to another by a virus such as a retrovirus or a bacteriophage. A specialized form of transduction is the introduction of oncogenes into cells by retroviruses.

Tumor Necrosis Factor:

A cytokine produced by monocytes/macrophages (TNF-α) and some T cells (TNF-β). They are directly toxic to neoplastic cells and are also involved in inflammation. - View Chapter -

Type B Intranuclear Inclusions:

A virus inclusion body is a focal area in a virus-infected cell that stains in a characteristic way. They are located in the nucleus or cytoplasm of the cell. Type A inclusions are acidophilic and type B inclusions are basophilic. - View Chapter -

W

Wart Hog:

A wild African pig with tusks and wart-like protuberances on the face. - View Chapter -

Wild Type:

The natural virus; such viruses are used as reference strains for the comparisons of mutants and variants of a particular virus. - View Chapter -