Vaccines Flashcards

1
Q

What part of the immune system are vaccines targeting?

A
  • Adaptive immunity and its memory
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2
Q

Anamnestic immune response

A
  • Denoting an enhanced reaction of the body’s immune system to an antigen which is related to one that has been seen before
  • Using memory
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3
Q

Vaccine induced immunity

A
  • Vaccination introduces pathogen in some form to the body and its cells
  • Immune response occurs
  • Immunity to the pathogen will peak and then begin to decrease
    »>Duration will fizzle off
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4
Q

Booster immunizations

A
  • Primary vaccination occurs and immune response occurs

Before the immune response dips too low, will give a booster vaccine
- This way we are not relying on memory and are extending length of protection
- ** Can let it dip below and force memory to activate immune response but it is risky and some individuals may not be able to survive

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5
Q

Concept of vaccination history

A
  • 1796- Edward Jenner vaccinated against smallpox by using cowpox (vaccinia) infected material
  • 200BC- Inoculation and vaccination by blowing antigen into nose
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6
Q

Vaccines as lifesavers

A
  • The most effective preventative measure
  • Looked at average of cases in 3 years prior to vaccination and saw a 93%-100% decrease in infection across 6 diseases
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7
Q

Administration routes

A
  • Injection
  • Oral
  • intranasal
  • Skin-patch
  • Edible
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8
Q

Economic value of vaccines

A
  • Effective means of preventing infectious disease
  • Cost effective by increasing health status
    o Better feed conversion
    o Better carcass weight
    o Decreases mortality
    o Avoids use of antibiotics
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9
Q

The “ideal vaccine”

A
  • Fast onset
  • Long duration of immunity
  • Highly effective (both prophylactic and therapeutic)
  • Efficient in all age groups and niche populations
  • Safe, no side effects
  • Cost effective
  • Easy to store, transport, and administer
  • DIVA vaccine
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10
Q

Prophylactic vs. therapeutic vaccines

A
  • Prophylactic: vaccines given to healthy animals as a preventative
  • Therapeutic: treating animals that are already ill
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11
Q

DIVA

A
  • Differentiate infected from vaccinated animals
  • Important to prove that the animal was vaccinated and so has antibodies, BUT that they are disease free and never actually had the disease
    o Allows for country or barn to be considered disease free, and supports trade
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12
Q

How do DIVA vaccines work?

A
  • The vaccine will have a marker (often a removed/deleted protein) that is different than the infection.

Example: Infection has 3 proteins that body will create antibodies for. Vaccine will only have 2 proteins, and will therefore only make antibodies for 2 proteins.

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13
Q

Why can’t you add another marker and make it a DIVA vaccine?

A

Because antibodies would still be made for the other proteins present in the vaccine so you couldn’t be sure that the individual had not been infected as well

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14
Q

What is a vaccine?

A
  • A substance that is given to stimulate a primary immune response
  • This immune response will prepare our body for contact with the actual disease or illness and once we come into contact with the pathogen, our body is able to mount a secondary immune response and hopefully avoid serious disease
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15
Q

Vaccine components

A
  1. Antigen
  2. Adjuvants
  3. Diluents, stabilizers, preservatives, trace components
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16
Q

Antigen in a vaccine

A
  • Foreign material
  • Subunit, inactivated, or attenuated
  • Single or multiple antigens
17
Q

Adjuvants in vaccine

A
  • Enhance immune response
  • Help to modulate the type of immunity (intracellular vs. extracellular)
  • Shorten onset and extend duration of immunity

Examples: oil in water, TLRs, combinations adjuvants

18
Q

Three main approaches to making vaccine

A
  1. Whole pathogen
  2. Parts/ subunits
  3. Genetic material (RNA/DNA)
19
Q

Types of whole vaccines

A
  1. Live-attenuated
  2. Inactivated (killed) vaccines
20
Q

Types of parts vaccines

A
  1. Recombinant (subunit) vaccines
  2. Vectored vaccines
21
Q

Types of genetic material vaccines

A
  1. DNA
  2. RNA
22
Q

Live-attenuated vaccines

A
  • Pathogen is live but attenuated, enters cells, replicates, brings danger-signals
  • Strongest response (humoral and cytotoxic response) of all vaccines
  • Long lasting
  • Safety concerns
23
Q

Live-attenuated vaccines steps

A
  1. Vaccines with alive vaccine can enter the cells and replicate
  2. Cell will display the viral proteins on its MHC I and on the membrane
  3. Cytotoxic T cells will see MHC I and destroy because not self, and the NK cells will destroy from seeing membrane proteins
  4. Infected cell will die and be phagocytosed by phagocytic cells which will then be presented on antigen presenting cells MHC II
  5. MHC II presentation to T helper cells causing activation and then B cell activation and antibody production
24
Q

Disadvantages to live-attenuated vaccine

A
  • Shedding of vaccine into environment
  • Safety concern- can revert back to full virulence
  • Not recommended during gestation or in immune compormised
25
Q

Inactivated vaccines

A
  • Pathogen cannot enter cell or replicate. Is a extracellular antigen
  • Grown in cell culture and then inactivated
  • Safe (young, pregnant animals)- no reversion to virulence
  • No shedding
  • Produces a strong antibody response only unless adjuvant added
  • Disadvantage: Needs additional adjuvants to help trigger stronger cytotoxic response and danger signals
26
Q

Inactivated vaccine steps

A
  1. Dead virus introduced to body. Cannot enter cells
  2. Phagocytic cells can phagocytose the inactivated vaccines and present on MHC II
  3. Pass on signal to T helper cells which results in activation of B cells and antibody production

** No activation of cytotoxic T cells because only causes extracellular response. UNLESS an adjuvant is used to trick the immune system into thinking that it is an intracellular pathogen

27
Q

Types of subunit vaccines

A
  • Split vaccine- directly purified from mechanicall disrupted pathogen
  • Recombinant vaccine- expressed on bacteria, mammalian cells, plants, baculovirus and then purified
28
Q

Recombinant (subunits) vaccines

A
  • Only part of a pathogen, cannot replicate or enter cell
  • Two types: Can be expressed in various expression systems or mechanically obtained
  • Short lived, strong antibody response but weak cytotoxic response
  • Safe, no live pathogen involved
  • No shedding
  • Cost effective
  • Disadvantage: needs adjuvant to trigger strong cytotoxic response
29
Q

Steps of recombinant (subunits) vaccines

A

** Same as inactivated vaccine**

  1. Dead virus introduced to body. Cannot enter cells
  2. Phagocytic cells can phagocytose the inactivated vaccines and present on MHC II
  3. Pass on signal to T helper cells which results in activation of B cells and antibody production
30
Q

Viral vectors

A
  • Used to deliver the subunit via a vector and get the subunit into the cell to produce both a humoral and cytotoxic response

Examples: Hemagglutinin or Neuraminidase, use adenovirus (chimp virus not pathogenic to humans)

31
Q

Vectored vaccines

A
  • Viral, bacterial and even parasite vectors (depending on target disease) which create a live pathogen that can enter cells. Vector itself does not cause disease.
  • Very effective, long lasting antibody and cytotoxic T cell response
  • Safe- cannot revert back to full virulence
  • Loading capacity, vector tropism, platforms
32
Q

Vectored vaccines steps

A
  1. Viral vector is able to enter the cells and replicate. Produces both viral and vector proteins
  2. Viral and vector proteins are displayed on cell surface activating NK cells, and on the MHC I activating cytotoxic T cells
  3. Killed cell will be phagocytosed by antigen presenting cells and present information on MHC II to T helper cells
  4. T helper cells will activate B cells and antibody production for both the viral target and vector
33
Q

Disadvantages to vectored vaccines

A
  • Results in immunity against the vector which prevents multiple booster immunizations or use of vector again
  • Shedding
34
Q

DNA and RNA vaccines

A
  • Nucleic acid encoding for 1 protein
    o DNA plasmids; mRNA or self-amplifying RNA (replicons)
  • No replication or disease causing
  • require carriers for delivery and then cell can take it up and translate material
  • faster manufacturing/easy to make
  • strong response, long lasting; both cytotoxic and humoral response
  • safe: no live pathogen
35
Q

DNA and RNA vaccine steps

A
  1. Inject DNA and RNA into cells (difficult!). Many options, pandemic discovered use of nanoparticles in which cells will take up.
  2. DNA will go to nucleus, RNA will stay in cytoplasm where it will undergo translation and make proteins
  3. Proteins will be displayed on MHC I where cytotoxic T cells will notice and become activated. Also presented on cell and released for phagocytosis by antigen presenting cells where they will present on MHC II for T helper cells and B cell activation/antibody production
36
Q

Disadvantages of DNA/RNA vaccines

A

Delivery is complicated. Requires carriers and/or nanoparticles
- Solution to this is using self-amplifying RNA (replicons). They make more copies of themselves like a virus but without its structure and ability to cause disease.

37
Q

Pathways targeting by vaccinations

A

Want to trigger both the endogenous pathway which results in cytotoxic response AND the exogenous pathway which activates T helpers and results in B cells with antibodies (humoral response)
- CROSS PRESENTATION

38
Q

Sequivity platform- MERCK

A

Custom vaccine production:
- Take pathogen from barn, they will sequence it and make specific RNA that addresses issue and make it into vaccine