Chapter 17 Microbiology

Who discovered vaccination?

Edward Jenner

types of active immunization

attenuated (live) vaccines, Inactivated (killed) vaccines, and Toxoid vaccines

Attenuated (live) vaccines

pathogens with reduces virulence, can cause mild infection, and activates microbes to stimulate a strong immune response

Inactive (killed) vaccines

dead whole-agent or subunit, not enough microbes for an immune response, multiple doses, use adjuvants

adjuvants

chemicals added to increase effective antigenicity

Toxoid vaccines

go after a toxin, not an organism, are chemically or thermally modified toxins used to stimulate immunity

Are toxoid vaccines useful for some bacterial disease?

yes

do toxoid vaccines require multiple doses?

yes, because they possess few antigenic determinants

Vaccine types in active immunization

Combination vaccines and vaccines using recombinant gene technology

Combination Vaccines

combine different organisms into one vaccine

Vaccines using recombinant gene technology

isolate DNA coding for antigen or antigenic protein and insert into DNA of virus or cell or into plasmid vector

Why are multiple doses of vaccines necessary?

to get memory back for antibodies

What are the problems associated with immunization?

mild toxicity, risk of anaphylactic shock, residual virulence, some preservatives added so they last longer

What is the heard immunity concept?

if most of the population is immune, the spread is way less

Passive immunotherapy

administration of antiserum containing preformed antibodies for immediate protection

limitations of antisera

contain antibodies against many antigens, con trigger allergic reactions, viral pathogens may contaminate antisera, and antibodies of antisera are degraded relatively quickly

Hybridomas

plasma cells with antibodies are removed from mice injected with antigen and joined with long-lived myeloma cells and they are fused together to produce more antibodies

Antibody-antigen Immune Testing

uses serology: the study and diagnostics use of antigen-antibody interactions in blood serum

Immune testing: Direct

looking for presence of antigen (if someone’s actively sick)

Immune testing: Indirect

Look for antibodies that have formed against antigens (if exposed at some point in time and developed memory cells)

Precipitation Testing

most simple, antigens and antibody mixed in the proper proportion form large complexes called precipitates

Immunodiffusion

one well containing antigen molecules on one side of agar plate while well containing antibodies against the antigen are on the other side and a line of immune precipitation shows up to form the zone of optimal precipitation

Agglutination Tests

cross-linking of antibodies with particulate antigens causes agglutination, positive equals agglutination of blood cells

Blood type A antigen

A

Blood type A Ig

Anti-IgGB

Blood Type B antigen

B

Blood Type B Ig

Anti-IgGB

Blood Type AB antigen

A and B

Blood type AB Ig

Anti-IgGa and Anti-IgGB

Titration

use of agglutination to quantify the amount of antibody in a serum sample, more agglutination equals more sick

Cytopathic effect

viruses introduced into appropriate cell cultures will kill the cells

Neutralization Tests

virus and antibody serum added to cell culture. absence of cytopathic effect indicated presence of antibodies in serum. Identifies whether individual exposed to a particular virus

Fluorescent antibody tests

use fluorescent dyes as labels

ELISA (enzyme-linked immunosorbent assay)

to detect presence of antibodies in serum, antigen inside of well and block everything else, then primary antibody is inserted, then enzyme-linked antibody specific for primary antibody is inserted and substrate if grabbed will change color.

Sandwich ELISA

Antigen being tested for is “sandwiched” between two antibody molecules. Antibody specific for antigen is inserted first then antigen from patient will bind if present

Immunochromatography

antigen solution flows through a porous strip and encounters labeled antibody, a visible line produced when antigen-antibody immune complexes encounter antibody against them