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Detection of orgs2b2
Immunological methods
| Question | Answer |
|---|---|
| An antibody to a given antigen is made fluorescent by coupling it to a fluorescent compound and when the antibody reacts with its antigen, the antigen-antibody complex emits fluorescence and can be detected by the use of a fluorescence microscope. | Fluorescent Antibody |
| a more rapid method for recovering salmonellae from foods than the conventional culture method (CCM); Results can be obtained in 50 hours; relies on antibody reaction with flagellated sallmonellae strains. | Enrichment Serology |
| employs the use of a semisolid phase; The method is conducted in a specially designed plastic device that has two chambers, one for selective broth and the other for a non-selective motility medium. | Salmonella 1-2 Test |
| This technique consists of adding a radioactive label to an antigen, allowing the labeled antigen to react with its specific antibody, and measuring the amount of antigen that combined with the antibody by the use of a counter to measure radioactivity. | Radioimmunoassay |
| method similar to RIA but employing an enzyme coupled to either an antigen or an antibody rather than a radioactive isotope Widely used to detect and quantate organisms and their products in foods. | enzyme-linked immunosorbent assay (ELISA) |
| have been widely used for the detection and quantitation of bacterial toxins and enterotoxins.; They have been employed to measure enterotoxins of staphylococci and C. perfringensand the toxins of C. Botulinum | Gel Diffusion |
| used for a number of other organisms including viruses and protozoa; magnetizable beads (about 2-3 um in size, about 106 -l O8 VmL) that are coated with antibody by incubating in the refrigerator for varying periods of time up to 24 hours. | Immunomagnetic Separation |
| antigens are not required; two comparable serologic methods yield results in 2-4 hours | Hemagglutination |
| The fluorescent antibody technique has had extensive use in both clinical and food microbiology since its development in what year? | 1942 |
| FA) technique can be carried out by use of either of two basic methods.: | Direct method and indirect method |
| - antigen coated by specific antibody with fluorescent label. This method detects the presence of the antigen (e.g., identify specific microorganism) | Fluorescent Antibody Direct method |
| antigen coated by homologous antibody, which is, in turn, coated by antibody to the homologous antibody bearing the fluorescent label). (e.g., demonstrate the presence of the antibodies in the serum) | Fluorescent Antibody indirect method |
| The fluorescent markers used in FLUORESCENT ANTIBODY (FA) are: | ◼ rhodamine B ◼ fluorescein isocyanate, ◼ fluorescein isothiocyanate |
| In addition to selective ingredients, salmonella 1-2 test contains the amino acid______________, which is selective for salmonellae | L-serine |
| two chambers of salmonella 1-2 test | one for selective broth and the other for non-selective motility medium |
| refers to methods that employ solid materials or surfaces onto which a monolayer of antibody molecules binds electrostatically. | Solid-phase radioimmunoassay (RIA) |
| Solid-phase radioimmunoassay (RIA) , solid materials used include: | ◼ polypropylene, ◼ polystyrene, ◼ and bromacetylcellulose |
| TRUE OR FALSE ◼ The ability of antibody-coated polymers to bind specifically with radioactive tracer antigens is essential to the basic principle of solid-phase RIA. | TRUE |
| ELISA is Synonymous with: | ◼ enzyme-multiplied immunoassay technique (EMIT) ◼ indirect enzyme-linked antibody technique (ELAT) |
| Variations of ELISA: | o Sandwich ELISA- the antigen is required to have at least two binding sites o Double sandwich ELISA – it employs a third antibody |
| ELISA commonly used enzyme | horseradish peroxidase |
| IN ELISA The amount of enzyme present is ascertained by | colorimetric determination of enzyme substrate |
| specific antibody is kept constant and enterotoxin (antigen) is diluted out. Following incubation for about 20 minutes, treated sheep red blood cells (SRBCs) are added. | hemagglutination-inhibition (HI) |
| antitoxin globulin is attached directly to SRBCs and used to detect toxin. When diluted toxin preparations are added, the test is read for HA after incubation for 2 hours. | reverse passive hemagglutination (RPH) |
| In HI, Hemagglutination (HA) (occurs /does not occur) only when antibody is not bound by antigen. | occurs (HI) |
| In HI, HA is prevented (inhibited) where toxin is (present/absent )in optimal proportions with antibody | present (HI) |
| In RPH, HA occurs only where optimal antigen-antibody levels occur | (for PRH) |
| In RPH, No HA occurs if no toxin or enterotoxin is (present/absent) | present (for RPH) |
Created by:
honeybunch
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