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Flashcards in Vaccines L8-10 Deck (91)
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1

Define vaccination.

The deliberate induction of an adaptive immune response by injecting a vaccine (a dead or attenuated, non pathogenic) form of the pathogen.

2

Define immunization.

The act of making someone, something immune to a particular disease.

3

____1____ can occur naturally or artificially.

____2____ can only occur artificially.

1. Immunization

2. Vaccination

4

Passive immunization

Protection by transfer of specific, high titre, antibody from an immune donor to a non immune recipient (____1____ transfer). Alternatively, immune cells from an immunized individual may be used to transfer immunity (____2____ transfer).

  • Gives immediate protection
  • Only offers transient effect and protection

1. Passive

2. Adoptive

5

Read

Naturally acquired passive immunity

  • Required for neonatal protection
  • IgG is transferred from mother to foetus
  • Maternal IgA is transferred through colostral transfer
  • An IgG trough in neonates exists between 3-6 months of age due to the decline in maternal IgG.

6

Describe the 3 month IgG trough.

Where the maternal IgG reduces and the child's IgG is not high enough to make up for it.

7

Define artificially acquired passive immunity.

Artificially acquired passive immunity is a short-term immunization by the injection of antibodies, such as gamma globulin, that are not produced by the recipient's cells.

8

More than a thousand years ago, the Chinese tried to prevent smallpox by  practice known as ____1____ (named after smallpox, or variola, virus). This involved peeling scabs from the lesions of smallpox survivors, drying and, grinding them to a powder and blowing them up the patient's ____2____.

The effects of ____1____ varied ranging from mild illness in most individuals to death in a few.

1. Variolation

2. Nose

9

Define immunological memory.

The ability of the immune system to respond more rapidly and effectively to a pathogen that has been encountered previously.

10

The secondary response reflects a larger number of antigen-specific cells (memory cells) present after the primary response that have persisted (can be for decades).

During the initial expansion of antigen-specific B cell clones, some of the progeny cells do not develop into ____1____ cells. Instead, they revert to small lymphocytes bearing the same ____2____ on their surface (memory B cells).

These memory B cells respond more quickly and more effectively than naïve B cells.

1. Plasma

2. BCR

11

Immunological memory

 

 

Obviously no single cell can last 30+ years. Therefore the memory B cells must somehow pass on their memory to their progeny.

12

A secondary immune response produces antibody with increased ____1____. This comes about by the process of somatic hypermutation (SHM) which causes alterations in the ____2____ regions of light and heavy chains of the memory cells. This is a random process that improves antigen binding ____1____.

1. Affinity

2. Variable

13

When B cells bind an antigen in the primary response, they are selected for.

In the secondary response the new B cells have competition with the selected for antibodies. This selection process (which carries on into the tertiary response) selects for the antibodies with the greatest affinity to the ____1____.

This all takes place in ____2____ centres.

Is sort of a survival of the fittest (greatest affinity) scenario.

1. Antigen

2. Germinal

14

Compared to naïve B cells, memory B cells are what? (6)

  • Long lived
  • Have increased frequency
  • Proliferate more rapidly
  • Produce more antibody
  • Produce higher affinity antibody
  • Produce antibodies with better effector functions (IgG and IgA)

15

State the main difference between naïve T cells and memory T cells.

How does this knowledge help us?

CD45RA expressed on both types. CD45RO only expressed on memory T cells.

These therefore act as markers for distinguishing between them.

16

Memory T cells are long lived, have increased frequency and ____1____ more rapidly than naïve T cells.

Naïve T cells express the tyrosine phosphatase CD45RA which does not associate with the ____2____.

Memory T cells express CD45RO which associates with both the ____2____ and co-receptor (CD4). This complex tranduces signals more effectively than the receptor on naïve T cells.

1. Proliferate

2. TCR

17

  • Effector memory T cells (upon Ag re-stimulation, rapidly mature into effector cells) and move into tissues (lose ____1____ expression). Release lots of effector associated cytokines e.g. IFN-g and IL-4
  • Central memory T cells (mature into effector cells slower and stays in LN for longer due to maintenance of ____1____. Take longer to secrete effector associated cytokines.

1. CCR7

18

Define chemokine.

Molecules that the immune system secrete that help target the cells to the correct place.

19

What is CCR7?

What is its function?

CCR7 is a chemokine receptor.

It detects the presence of chemokines. CCR7 binds to chemokines and keeps the cells in the lymph node.

20

Read

What must an effective vaccine do to induce memory?

  1. Be processed by APC for MHC presentation (generates Signal 1). Activate APC (induces co-stim (Signal 2) and Signal 3 (cytokines)
  2. Induce high levels of T and B cell primary activation, hence   give a high efficiency of generating memory cells.

  3. Activate multiple T cell clones reactive with more than one epitope (to counter any antigenic variation of  parasites).

  4. Provide a constant and long lasting source (depot) of antigen in lymphoid tissue.

  5. Induce protective response(s) to pathogen without causing disease.

21

List the requirements of an effective vaccine. (8)

  • Safe
  • High level of protection
  • Long-lasting protection
  • Right type of response (local, systemic, antibody or T cells)
  • Low cost
  • Stable (often in high temperatures)
  • Easy to administer
  • Minimal side-effects

22

List the 5 types of active immunization.

  • Live attenuated vaccines
  • Killed vaccines
  • Sub-unit vaccines
  • Conjugate vaccines
  • Recombinant vaccines

23

State the pros of live attenuated vaccines. (4)

  • Single dose effective
  • May be given by natural route
  • May induce local and systemic immunity
  • May induce right type of response

24

State the cons of live attenuated vaccines. (4)

  • Reversion/alteration to virulence
  • Possibility of contamination
  • Susceptible to inactivation
  • Can cause disease in immunocompromised host

25

Give examples of live attenuated vaccines (6)

  • Measles, mumps, rubella (MMR)
  • Oral polio (Sabin)
  • BCG
  • Yellow fever

26

Give examples of killed vaccines. (4)

  • Salk polio vaccine
  • Pertussis (whooping cough)
  • Typhoid
  • Cholera.

27

State the pros of killed vaccines. (2)

  • They are stable in storage

  • Killed vaccines are no longer pathogenic and therefore can no longer cause disease

28

Recombinant Subunit Vaccines

To avoid the problems involved in bulk culture of pathogens recombinant vaccines have been introduced.

Hepatitis B was the first recombinant vaccine licensed for human use. Antibodies to Hepatitis B ______ antigen (HBsAg) are protective in natural infections.

Surface

29

Purified Subunit Vaccines

These are vaccines that are made from purified components of pathogens. These components elicit protective immune responses, without the pathogenicity.

Give 2 examples.

  • HiB (Haemophilus influenza B which causes meningitis, pneumonia etc). The vaccine is made from purified capsular polysaccharides.

  • Influenza vaccine consists of purified haemagglutinin (H) and neuraminidase (N) antigens of the particular strain that is prevalent.

30

Define a conjugate vaccine.

A conjugate vaccine is created by covalently attaching a poor (polysaccharide) antigen to a carrier protein (preferably from the same microorganism), thereby conferring the immunological attributes of the carrier to the attached antigen.