Lecture 22: Controlling Viral Infections

Question 1

What is a vaccine?

Answer 1

A biological product that can be safely used to induce an immune response that confers protection against infection and/or disease upon subsequent exposure to a pathogen.

Question 2

What are the 4 different types of vaccine?

Answer 2

Live (attenuated)

Killed Whole organism

Subunit (purified protein, recombinant protein, polysaccharide, peptide)

Nucleic acid

Question 3

What are the requirements for an effective vaccine?

Answer 3

• Induction of an appropriate immune response
• The vaccinated individual must be protected against the disease caused by the virulent strain
• Vaccine must be safe and acceptable (should cause no disaease, and must have minimal side effects)
• Protection must be long-lasting
• Virus must be genetically stable (e.g, for live-attenuated vaccine)
• Storage considerations must be taken into account (i.e mRNA vaccine must be stored at low temperature)
• Must be cheap
• Must be able to be effectively administered

Question 4

Describe live (attenuated) vaccines

Answer 4

• Contains the whole virus that has been weakened or attenuated to produce an immune response similar to that seen during natural infection. (uses the wild type strain)
• The weakened virus is recognised by the immune system to trigger a response without causing illness
• This response builds immune memory so your body can fight off the same viral infection in future encounters.

Question 5

What is an advantage of live (attenuated) vaccines?

Answer 5

They create a strong, long-lasting immune response, but they don’t overdo it

Question 6

What is a disadvantage of live (attenuated) vaccines?

Answer 6

They’re often not suitable for immunocompromised individuals

Question 7

What are some examples of live/attenuated vaccines?

Answer 7

Measles, mumps, rubella,

Rotavirus

Oral polio vaccine

Live attenuated influenza vaccine.

Question 8

Describe killed/inactivated vaccines

Answer 8

• They contain a whole virus which has been killed or have been altered, so that they cannot replicate

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Question 9

What are some examples of killed/inactivated vaccines?

Answer 9

Inactivated polio vaccine or IPV,

inactivated flu vaccines

Hepatitis A vaccine

Rabies vaccine

Question 10

What is an advantage of killed/inactivated vaccines?

Answer 10

May be suitable for immunocompromised individuals.

Unlike live attenuated vaccines, there is no risk of the virus reverting to a virulent form.

Question 11

What is a disadvantage of killed/inactivated vaccines?

Answer 11

They don’t create a strong, long-lasting immune response, so multiple doses may be required

Question 12

Describe subunit vaccines

Answer 12

They don’t contain the whole virus, they contain one or more specific component/antigens usually from the surface of the virus.

Antigen usually a capsid or membrane or surface protein

Question 13

What are some examples of subunit vaccines?

Answer 13

Influenza subunit vaccine

Hepatitis B virus subunit vaccine

Question 14

What are some advantages of subunit vaccines

Answer 14

• May be suitable for immunocompromised individuals.
• Can be used to make viral-like particle vaccines
• No subculturing is necessary
• No infectious viruses are needed

Question 15

What are some disadvantages of subunit vaccines?

Answer 15

Don’t create a strong, long-lasting effect

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