Chapter 18 test 4

Why does the reaction of a precipitation test become visible only in a narrow range?

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Compare and contrast direct and indirect fluorescent-antibody tests.

Direct FA tests-are usually used to ID a MO in a clinical specimen. the specimen containing the antigen to be ID is fixed onto a slide, flourescence is added, the slide is incubated, and the results are observed. Indirect FA-tests- are used to detect the prescence of a specific antibody in serum following exposure to a MO. they are often more sensitive than direct tests. Slide is made and observed. uses anti-human immune serum globulin (anti-HISG)

Experience has shown that attenuated vaccines tend to be more effective than inactivated vaccines. Why?

Live vaccines more closely mimic an actual infection. as the pathogen reproduces w/i the host cells, cellular, as well as humoral, immunity usually is included. long term effectiveness occurs b/c the attenuated viruses replicate in the body, increasing the original dose and acting as a series of secondary booster immunizations

Western blotting

This protein seperation technique (sometimes called the protein immunoblot) is a widely used analytical technique used to detect specific proteins in the given sample of tissue homogenate or extract. It uses gel electrophoresis to separate native or denatured proteins by the length of the polypeptide (denaturing conditions) or by the 3-D structure of the protein (native/ non-denaturing conditions). The proteins are then transferred to a membrane (typically nitrocellulose or PVDF), where they are probed (detected) using antibodies specific to the target protein. There are now many reagent companies that specialize in providing antibodies (both monoclonal and polyclonal antibodies) against tens of thousands of different proteins. Commercial antibodies can be expensive, although the unbound antibody can be reused between experiments. This method is used in the fields of molecular biology, biochemistry, immunogenetics and other molecular biology disciplines.

What is the etymology (origin) of the word vaccine?

To honor jerners work w/ cowpox as a vaccine for smallpox (vacca meaning cow).

Explain why vaccination works.

Vaccination process: -someone is vaccinated -B cells are activated and go through clonal selection -person is exposed to pathogen -antibodies are produced rapidly in response to pathogen. -antibodies produced by memory B cells initiate the destruction of pathogen -helps the body prepare in advance to find an illness; forces the body to produce antibodies and long term memory cells against the infection

Define vaccine.

a preparation of antigenic material used to induce immunity against pathogenic organisms.

Define adjuvant.

aluminum salts combined with many vaccines. improve innate response, especially activation of toll-like receptors. used for surgery

Differentiate the following, and provide an example of each: attenuated, inactivated, toxoid, subunit, and conjugated vaccines.

attenuated: reduced virulence but still alive-MMR inactivated: dead-salk polio toxoid: inactivated toxin-tetanus subunit: antigen without a viral particle... antigenic fragments of a microorganism that best stimulate an immune response-recombinant B hepititus conjugated: bacterial capsular polysaccharide joined to a protein to enhance immunogenicity-deals with children with poor immune systems

Vaccination is often the only feasible way to control most viral diseases; why is this?

because viral diseases cannot be effectively treated with once contracted.

Differentiate direct from indirect agglutination tests.

direct detects antibodies against relatively large cellular antigens, such as those on red blood cells, bacteria, and fungi. indirect the antibody reacts with the soluble antigen adhering to the particles.

Define monoclonal antibodies, and identify their advantage over conventional antibody production.

laboratory produced molecules that are set to mimic antibodies in your body by attaching to defects in cancer cells. The monoclonal antibodies make it easier for the immune system to recognize cancerous cells as dangerous. They are uniform, highly specific, and can be produced in large quantities. (used for cancer, crohns disease, asthama, and multiple sclerosis)

Explain the value of vaccines, and discuss acceptable risks for vaccines.

no vaccine will ever be perfectly safe or perfectly effective (or any antibiotic or drug for that matter). nevertheless, vaccines are still the safest, most effective means of preventing infectious disease in children.

Differentiate sensitivity from specificity in a diagnostic test.

sensitivity is the probabillity that the test is reactive if the specimen is a true positive specificity= the probability that a positive test will not be reactive if a specimen is a true negative

Contrast subunit vaccines and nucleic acid vaccines.

subunit vaccine a vaccine produced from specific protein subunits of a virus and thus having less risk of adverse reactions than whole virus vaccines. Nucleic acid vaccine-immunization that elicits immune responses similar to those induced by live, attenuated vaccines.

Define hemagglutination.

when agglutination reactions involve the clumping of red blood cells