Vaccination

Question 1

What is herd immunity?

Answer 1

The indirect protection from infection of susceptible members of a population, and the protection of the population as a whole, which is brought about by immune individuals
- high numbers of the population need to be vaccinated for this to be effective

Question 2

What is passive immunity and when is it used?

Answer 2

• Provides rapid protection by administration of specific antibodies
• Often used in cases of accidental exposure of susceptible animals to pathogens
• Used as supportive therapy in animals with compromised immune systems
  e. g. colostrum in newborns

Question 3

What are the 2 preferred responses to vaccination?

Answer 3

• Stimulation of long-term memory

- Rapid secondary response

Question 4

What type of cells are killed by Cytotoxic T lymphocytes?

Answer 4

• virus infected cells
• cancer cells
• cells containing intracellular bacteria
• do not kill free virus

Question 5

What kills free virus?

Answer 5

Virus neutralising antibody

Question 6

Why are subcutaneous vaccines so useful?

Answer 6

• Skin contains specialised monocyte-derived epidermal cells = Langerhans cells
• Precursors of dendritic cells
• Capture and process antigens in skin
• Travel in lymph to lymph node
• Become follicular dendritic cells
• Stimulate T-cells very effectively

Question 7

What is an adjuvant?

Answer 7

Non-specific enhancers of immune responses to non-living vaccines

Question 8

How do adjuvants function?

Answer 8

• Enabling slow release of vaccine antigens into the body to enhance immune recognition and response
• Stimulating the immune system non-specifically

Question 9

Give 3 examples of adjuvants

Answer 9

• Aluminium and calcium salts
• Microbial products
• Synthetic agents
• Exogenous cytokines

Question 10

What are the pros and cons of using dead vaccines?

Answer 10

• Safer than live vaccines
• Give better antibody responses compared to CMI
• Less immunogenic
• Have to be administered more often
• Not effective by natural infection route
• Need adjuvants for effective immunity

Question 11

What are live attenuated vaccine antigens?

Answer 11

• mutants selected in vitro to reduce virulence but retain antigenicity
• Live “vectors” into which are inserted specific gene products