Chapter 18 Flashcards
Immunization
- Process of inducing immunity
- Inducing artificially acquired immunity
Active Immunity
- Immune response upon exposure to an antigen
- Naturally: Following illness
- Artificially: After immunization
Passive Immunity
- Naturally: During pregnancy: IgG crosses Placenta
- Artificially: Antibodies from another person or animal
Attenuated Vaccines
- Strong immune response
- Weakened form of pathogen
- Strain replicated in vaccine recipient
- Causes infection with undetectable symptoms
- Microbes multiply in body
- Can become pathogenic
- Needs fridge
Inactivate Vaccines
• Toxoids: toxins treated to destroy toxic part, retain antigenic epitopes (diphtheria, tetanus)
• Subunit vaccines: consist of key protein antigens or antigenic fragments (acellular pertussis (aP) vaccine)
• Recombinant vaccines: subunit vaccines produced by genetically engineered microorganisms (hepatitis B virus)
• VLP (virus-like particle) vaccines: empty capsids produced by genetically engineered organisms (HPV)
• Polysaccharide vaccines: made from capsules
• Conjugate vaccines: polysaccharides linked to proteins
-Converts polysaccharides into T-dependent antigens
Immunoassays
Use antibody-antigen specificity
– Can test individual for unknown but suspected pathogen
• Binding of known antibodies identifies unknown pathogen
– Can test patient for infection of known pathogen
• Binding of patient’s antibodies to known pathogen demonstrates current or previous infection
Seronegative
Individual not yet exposed to antigen
Seropositive
- Individual has been exposed
- Specific antibodies to pathogen
Seroconversion
-process of producing antibodies
Serology
Study of in vitro antibody-antigen
interactions
Polyclonal Antibodies
- Animals immunized with whole or partial agent; resulting antibodies collected from animal’s serum
- Yields polyclonal antibodies: multiple B cells responded, produced mix of antibodies to variety of epitopes
- Anti-human IgG antibodies produced by animals immunized with IgG from human serum
Monoclonal Antibodies
• Recognize only a single epitope • Difficult and expensive to produce • Human immune system less likely to destroy • Some used to treat certain cancers 
Precipitation reactions
- Antibodies biniding to soluble antigen form insoluble complexes
- Immunodiffusion test
Agglutination reactions
-Detects antigens or antibodies in body fluids
– Direct agglutination: antibody mixed with antigen ; binding yields clumping
– Passive agglutination: Amplifies aggregation formation
– antibodies or antigens attached to particles
Labeling Antibodies
– Enzymes, fluorescent dyes, radioactive tags
– Direct tests: identify unknown antigen or bacteria
• Antigen attached to solid surface
• Labeled antibodies of known specificity added
• Washing step removes unbound; binding identifies antigen
– Indirect tests:detect antibodies in patient’s serum
• Known antigen attached to surface; serum added
• Unbound antibodies washed off
• Secondary antibodies (e.g., anti-human IgG) added
• Binding identifies primary antibody bound to antigen
