Vaccination

Question 1

What virus causes smallpox and what vaccine is used for it?

Answer 1

Variola virus causes smallpox and vaccinia virus can be used in vaccines.

Question 2

What is subacute sclerosing parencephalitis?

Answer 2

A slow viral infection of the central nervous system associated with prior measles infection

Question 3

What are the principles of vaccination?

Answer 3

Pathogens are altered so that they maintain their antigenicity while losing virulence.

Vaccine induces primary antibody and cellular immune response.

Memory cells must be able to proliferate rapidly in secondary immune responses induced in natural infection.

Question 4

What is the difference between active and passive immunity?

Answer 4

Active immunity is produced by person’s own immune system with specificity and memory and can last for decades.

Passive immunity is immunity that is transferred from another person or animal (antibodies only). This kind of protection wanes with time due to antibody half life.

Question 5

What are the type of vaccines?

Answer 5

Live vaccines (vaccinia)

Attenuated live vaccines

Inactivated vaccines (killed)

Component vaccines (toxoids or subunits)

Polysaccharide and polypeptide (cellular fraction) vaccines

Conjugate vaccines

Question 6

How are attenuated vaccines made?

Answer 6

They use pathogens with reduced virulence.

Question 7

What are the pros and cons of attenuated vaccines?

Answer 7

Pros:

Induces strong immune response with strong memory cell formation.

Cons:

Can result in mild infection

In some cases can cause disease. (residual virulence)

Question 8

How are live attenuated vaccines made?

Answer 8

Pathogenic virus is isolated from a patient and grown in human cultured cells.

Cultured virus is used to infect monkey cells.

Virus acquired many mutations allowing it to grow well in monkey cells.

Virus no longer grows well in human cells and can be used as a vaccine.

Question 9

What vaccines use attenuated viruses?

Answer 9

Polio

Measles

Mumps

Rubella

Varicella

Question 10

What are the pros and cons of using inactivated and component vaccines?

Answer 10

Pros:

More safe and are not capable of causing infection.

Can be effective when used with adjuvants.

Cons:

Killed microbes and components don’t provide many antigenic molecules to stimulate immune system.

Question 11

What are adjuvants?

Answer 11

Molecules used to increase effective antigenicity. Activates the innate immune response.

Question 12

What are toxoid vaccines?

Answer 12

Vaccines of non-lethal version of toxins.

Question 13

What are polysaccharide vaccines?

Answer 13

Some bacteria kill without producing toxins. Polysaccharide vaccines use a piece of the bacterial polysaccharide capsule as the trigger of immune response.

Question 14

Why are polysaccharide vaccines not effective in children <2 years of age? How can this problem be solved?

Answer 14

Their T-independent immune systems are not matured but by attaching polysaccharide to a protein it can be converted from a Tindependent to a Tdependent response.

Question 15

What are conjugate vaccines?

Answer 15

Protein and polysaccharide conjugate

Question 16

What are some new molecular approaches to production of vaccines?

Answer 16

Viral or bacterial genes are cloned into genome of another virus and the live virus is used as a vaccine.

Question 17

What kind of vaccine is HPV?

Answer 17

noninfectious virus-like particles.

Question 18

What do VLPs do?

Answer 18

They induce high titres of virus neutralizing antibodies even in the absence of an adjuvant.

Question 19

How safe are vaccines?

Answer 19

Mild toxicity is most common.

Risk of anaphylactic shocks.

Residual virulence from attenuated viruses.

Allegations from antivaxxers caused by wakefield paper

Question 20

What are the 2 forms of polio vaccines?

Answer 20

Sabin attenuated vaccine (grows in epithelial cells and does not grow in nerves so doesn’t cause paralysis and this creates gut immunity to polio (IgA)

Salk killed vaccine is a formaldehyde-fixed virus which does not run the risk of reversion does not produce gut immunity, and cannot wipe out the wild-type virus. [this is used when the polio virus has already been wiped out]

Question 21

Why are live viral vaccines used in preference to killed/inactivated viral vaccines?

Answer 21

Live viruses create a more complete immune response and trigger a more adequate immune memory.

Question 22

What are the limitations of using passive immunity?

Answer 22

Can trigger hypersensitivity reactions

Viral pathogens may contaminate antiserum being delivered.

Antibodies of antisera are degraded quickly

Question 23

What is immunogenicity?

Answer 23

Capacity to produce the most immunogenic vaccine.

Question 24

How can immunogenicity be increased?

Answer 24

Using larger molecules.

Inducing proteins subcutaneously

Making proteins very different to self proteins

Making adjuvants slow releasing.

Question 25

What are the features of the ideal vaccine?

Answer 25

Safe

Protective

Gives sustained protection

Induces neutralizing antibodies

Induces T cell response

Few side effects and reactions.