Antibodies and Vaccines Flashcards
Antibody Structure
Hinge region: segment of heavy chain
- Can bend which lets 2 antigen binding sites to move independently
- Assists in effector functions, like complement cascade
Isotype Definition
Different antibody class
Heavy chain constant region variation
Allotype
Amino acid difference in cosntant region
IgG1 versus IgG2a
Idiotype
Variable region that determines antigen specificity
Fab Fragment
Antigen binding site, very variable because of different antigens
Fc Fragment
Stem of the Y
Almost identical between antibodies, other phagocytes recognize antibodies
Fce: on mast cells allergic response
Fcy: IgG
Class Switching
From cytokines of Th cells
Enzyme involved: cytidine deaminase (AID)
- Epitope recognition does not change no matter the class switch
Antibody Synthesis
Primary vs secondary
Primary
IgM primary antibody
- Lag: none detected
- Log: antibody titer increases
- Plateau: titer stabilizes
- Decline: catabolized
Secondary
Same 4 phases, but with memory
- Time: shorter lag, longer plateau, gradual decline
- Type of Ab: IgG
- Antibody titer: higher
How Do Antibodies Stick To Antigens?
Affinity: initial force of attaction between Fab site on Ab and single epitope on antigen
Avidity: sum of all attractive forces between Ab:Ag, higher with more sites like in IgM (10 sites)
- Valence proportional to avidity
Ag:Ab Interaction: Bond Types
Noncovalent: weak but can have multiple bonds so it can be better force
“Goodness of Fit”
Strongest bonds develop when Ag and Ab are close to each other, and the shapes are matching
What is a Vaccine?
Goal
Solution of weakened or kileld pathogens, or their components
Goal: produced artificially acquired active immunity
Immunization Definition
Process by which a person becomes protected from disease
Live Attenuated Vaccine
Advantages, disadvantages, examples
Advantages
- Close to natural infection
- Long immunity, little dose
- Easy to create
Disadvantages
- Microbe can maybe revert back to virulent form
- Not everyone can receive, immunocompromised
- Needs refrigeration
Classic type
Rotavirus, herpes, MMR
Inactivated Vaccine
Advantages, disadvantages
Advantages
- Stable, no fridge
- More safe, doesn’t mutate back
Disadvantages
- Weaker immune response
- More doses
Classic type
Flu
Subunit/Conjugate Vaccine
Pros, cons
Advantages
- Low adverse reaction
- Very stable
- No live components
Disadvantages
- Difficult to get antigen
- No guaruntee that memory will form
Classic type
HBV
Conjugate Vaccine
Bacterial coat?
Bacterial polysaccharide coat: disguses antigen
- Polysaccharide binds to carrier protein, induces longer term response
Classic type
Toxoid Vaccine
Pros, cons
Advantages
- Bacterial toxin, inactivated and safe
- Stable
Disadvantages
- Hard to get best antigen
- Several doses, needs adjuvant
- Not very immunogenic
- Adverse reaction
Classic type
Tetanus
Novel Vaccine Types
DNA Vaccine
- Stronger response, uses microbes genetic material to code for antigen
- Easy, cheap
Recombinant Vector Vaccine
- Attenuated virus or bacterium vector, introduce the DNA to body
- Close to natural infection
- Strong immune response
Combination Vaccines
More than one antigen in the same vaccine
- Can be cheaper
- MMR, DTwP
Components of a Vaccine
5
- Antigens
- Stabilizers for storage
- Adjuvants: stimulate Abs to make more effective, used in inactivated vaccines
- Antibiotics: prevent bacterial contamination
- Preservatives: prevent contaminant growth
Characteristics of a Vaccine
Must do what? 3
- Produce protective immunity with little side effects
- Immunogenic enough to make strong response
- Stable shelf life while still effective
Factors Influencing Vaccination
2
- Age: target youngest at risk of disease
- Immune status
Host Repsonse
Possible adverse reactions
- Inflammatory response
- Hypersensitivity
Over time vaccine immunity may wane
- Booster used
