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SEM 4: Immunology > Vaccines - Bacterial and Viral > Flashcards

Vaccines - Bacterial and Viral Flashcards

1
Q

Vaccines to remember

A
  • Neisseria meningitidis group C, B, A, Y, W
  • Haemophilus influenza type B
  • Streptococcus penumonia
  • Influenza virus
  • Tuberculosis (BCG)
  • Tetanus, diphtheria and pertussis
  • Measles, mumps and rubella
  • Polio, hepatits B, HPV and VZV
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2
Q

Why is there no cross-protection between different vaccine strains?

A

This is due to the polysaccharide of the bacteria (capsule) being different and therefore the vaccine cannot protect against both.

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3
Q

When was the vaccine for meninogoccal infections group A, C,, W and Y made?

A

The vaccine for Group C, A, W and Y were all made in 1999. They are made of conjugated polysaccharides. This is because children under the age of 2 aren’t good at making antibodies.

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4
Q

Why was the vaccine for Group B different than the other groups?

A

This is because the sugar component polysaccharide of the virus was based around silicic acid which is present on all eukaryotic cells. This means a vaccine that wouldn’t induce an autoimmune response needed to be made. This was only introduced in 2015 and was only given to babies after the 1st May so other groups were still vulnerable.

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5
Q

What is Bexsero and how does it work?

A

The vaccine given which is used to target the surface protein (non-variant) of the bacteria that were common in all the types of meningococcal infections.

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6
Q

What are the surface proteins in the meningococcal bacteria that Bexsero targets?

A
  • Factor H binding protein (fHbp)
  • Neisseria Heparin binding antigen (NHBA)
  • Neisseria adhesion A (NadA)
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7
Q

What other parts of the bacteria does the Bexsero target?

A

It targets outer membrane vesicles (OMV) on the group B type which meant all the types of meningococcal infections are vaccinated against.

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8
Q

What are the issues with the vaccine?

A
  • Not cost effective
  • Not all serotypes of group B were covered
  • 88% efficacy and strain coverage
  • Duration of protection was 10 years
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9
Q

What is the Men ACWY vaccine?

A

Combined vaccine developed in Aug 2015 to replace the MenC vaccine. This is because from 2009, there was a rise in MenW cases in the young adult community which is a more invasive and virulent disease.

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10
Q

Why was Men ACWY given?

A

Done to protect the risk group and also prevent the spread in the wider community. It also provided as a “catch-up programme” which is for any person who might’ve missed the vaccine.

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11
Q

Which vaccines are 2 month old babies given?

A

Given hexavalent vaccine (6 vaccines):

  • DTaP - diphtheria, tetanus, pertussis
  • IPV - inactive polo virus
  • Hib and HepB
  • PCV - pneumococcal vaccine
  • MenB and MenC
  • Rotavirus
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12
Q

What are diphtheria, tetanus and pertussis?

A

All toxin mediated diseases; therefore, it is a subunit vaccine based on toxoids. It needs to be given 3 times.

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13
Q

How is the IPV vaccine given?

A

Used to be given as a live attenuated virus but isn’t given like that anymore due to the reversion to virulence. It needs to be given 3 times.

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14
Q

What is the Hib vaccine and when did the HepB vaccine become important?

A

Hib is a bacterial infection that causes meningitis. HepB vaccine was included in 2017 because it used to be in low prevalence in the UK but then it started to increase, and the babies were acquiring it from their mothers, which placed a massive burden on the NHS and therefore vaccination against it was then introduced.

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15
Q

What is the structure of the HepB vaccine?

A

It is a subunit vaccine based on recombinant proteins on the surface of the HepB virus. Because it is a subunit vaccine, it needs to be given 3 times.

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16
Q

What type of vaccine is the pneumococcal vaccine (PCV)?

A

It is a subunit vaccine based on conjugated polysaccharide for streptococcus pneumonia. It needs to be given in boosting doses - 3 times.

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17
Q

Why is there a MenB vaccine?

A

MenB is the main cause of meningococcal septicaemia. It is a subunit vaccine and therefore needs to be given 3 times.

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18
Q

Why and When is MenC vaccine given?

A

It is not very common, however MenB vaccine does not cross protect against it so it is still given (not in 2 months old babies however).

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19
Q

What are the symptoms of rotavirus?

A
  • Can cause viral infectious acute watery diarrhoea and hospital admissions
  • Low death rates, however higher rate of subsequent infections and therefore places a burden on the NHS.
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20
Q

What type of vaccine is rotavirus?

A
  • A live attenuated viral vaccine and therefore in theory only needs to be given once, but it is given twice in practice.
  • It is given twice because although the vaccine is good at protecting against severe virus, it does not have good efficacy for mild disease and so another boost is given to increase the efficacy.
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21
Q

Why is the rotavirus vaccine given twice?

A

This is also done because there are at least different serotypes for this virus and the first boost doesn’t protect against all of them, the second boost allows the protection against all. Also, to have a better efficacy for mild disease.

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22
Q

When is the MMR vaccine given?

A

It is given to 1 year olds not to 2 month old babies - it isn’t part of the hexavalent vaccine.

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23
Q

What is the MMR vaccine?

A

A live attenuated vaccine however, given twice to make sure a lot of children who didn’t respond or get vaccinated have it.

24
Q

Why is the MMR vaccine given twice?

A

It is done to reduce the infectious pool and protect those that can’t be vaccinated such as children under 12 months (the vulnerable window).

25
Q

Why is the MMR vaccine given at 12 months?

A
  • Given because all pregnant women are vaccinated against MMR and so they have maternal antibodies.
  • This means the antibodies are able to transfer to the newborn’s blood and neutralise live attenuated virus, this means the vaccine would have no effect.
26
Q

What is haemophilus influenza type B?

A

A paediatric disease usually seen in 6 months to 3 year olds, due to bacterial infection which causes a number of serious illnesses including; nasopharyngitis, otitis media, sinusitis, bronchitis, pneumonia and epiglottis (requires tracheotomy), can spread further and cause bacteraemia, septic arthritis and menigitis. If not treated, it causes neurological disorders or death.

27
Q

What type of vaccine is Hib?

A

It has 99% effectiveness against type B.
It is part of the conjugated vaccine - capsule polysaccharide linked to conjugate diphtheria/tetanus toxoids and outer membrane proteins (OMP).

28
Q

What causes diphtheria?

A

Caused by corynebacterium diphtheria
It is a non-invasive, mucosal surface pathogen, however, it produces toxins which have systemic and local effects.
Part of DTaP

29
Q

What are the effects of diphtheria toxins?

A

They are produced locally and act on distant targets. They are absorbed by lymphatics which cause systemic effects such as damaging heart, kidney, nerves and adrenals.
It kills epithelial cells and polymorphs gelatinious exude.
It causes ulcerations, and necrosis leading to pseudomembrane. Local inflammation, swelling of lymph nodes and respiratory obstruction

30
Q

What is tetanus and what causes it?

A

It is a neurotoxin disease that is part of DTaP. It is caused by clostridium tetani which is a G+ve bacteria that is spore forming.

31
Q

What are the effects of tetanus?

A
  • Produce a toxin that acts on neurons and blocks the release of neurotransmitters at the inhibitory synapse (GABA and glycine.
  • This leads to unopposed continuous excitation which leads to the locking of the muscles and spastic paralysis.
32
Q

How does the tetanus vaccine work?

A

It works by generating antibodies which neutralise the toxins and therefore, they can’t cause the disease anymore.

33
Q

What is pertussis?

A

It is whooping cough. A multi-toxin disease and part of the DTaPvaccine.

34
Q

What was side effects of the previous vaccine for pertussis?

A

It had a high toxicity and therefore lead to fever and headaches. It was made with whole killed bacteria.

35
Q

What is the current vaccine for pertussis?

A

A low risk acellular vaccine is used. It is a subunit vaccine which contains adhesion, pertussis toxoids and outer membrane proteins combined together into a multisubunit acellular vaccine. This is safer and neutralises the toxins via the release of antibodies.

36
Q

How does the pertussis vaccine work?

A

It creates antibodies against adhesion molecules, surface molecule and toxins, present in the molecule from adhering to the mucosal surfaces of the respiratory tract. If it cannot adhere, it cannot cause disease. As well as this, the antibodies are neutralising so if the pathogen does adhere and poduces toxins, the neutralising antibodies can neutralise that.

37
Q

What is the aim of the influenza vaccine?

A

To protect those who are most at risk of serious illness or death.
To reduce the circulation of the virus, therefore it is offered to all on the NHS.

38
Q

Who gets the influenza vaccine?

A
  • People aged 65 and above due to comorbidities
  • Children aged 6 months or over in a clinical risk group
  • Those living in long stay residential facilites
  • Those who care for elderly or disabled people
  • Those who work in the health and social care
  • Those who work in close contact with poultry due to new emerging viruses
  • All children under the age of 9 because they are the main transmitters
39
Q

What does the influenza vaccine target?

A

It targets the outer antigens of the virus, such as haemagglutinin and neuraminidase.

40
Q

What is unique abou the influenza virus?

A
  • It undergoes antigenic drift: gradual accumulation of mutations in the haemaglutinin protein
  • It also underoges antigenic shift: the recombination of viruses to acquire a completely new gene.
41
Q

What is the influenza vaccine based on every year?

A

Based on what is thought to be the next common circulating strain in the following year, to be incorporated into the vaccine for the subsequent year.

42
Q

Why is it difficulat to vaccinate against influenza?

A

It is difficult to guess what the strain is.
- In 2016-17; over 65s had a weak response to the vaccine, this is because they didn’t respond well. In 2018, an adjuvant was added in the vaccine which is a live and inactivated flu vaccine with additional strains added to offer more protection.

43
Q

What causes pneumococcal infections?

A

Caused by the bacteria streptococcus pneumonia.

44
Q

Describe the spectrum of pneumococcal infections

A

Leads to multiple diseases such as meningitis, otits media, pneumonia, sinusitis, soft tissue infection and arthritis.

45
Q

Who can be infected with streptococcus penumonia and who is vaccinated?

A

Young children under the ages of 1 or in the elderly. Therefore, all children and over 70s are vaccinated against this.

46
Q

What is the pneumococcal vaccine and what are the two types?

A

A conjugated polysaccharide vaccine.

  • Type 1: Pneumococcal polysaccharide vaccine PPV23
  • Type 2: Pneumococcal conjugate vaccine PCV-13V.
47
Q

Who is given PPV23?

A
  • Given to adults and children over 2 years
  • Protects against the 23 most common serotypes
  • Isn’t given to under 2 because they can’t make long lasting protective immune response to polysaccharide vaccines
48
Q

Who is given PCV-13V?

A
  • Given to children under the age of 2
  • Protects against 13 of the most common serotypes
  • Conjugated with T/D toxoids and OMP (very similar to Hib vaccine)
49
Q

What does human papillomavirus (HPV) cause?

A

Causes genital warts

However, serotype 16 and 18 can cause cervical cancer in young women

50
Q

What are the 2 licensed vaccines for HPV?

A

Gardasil: protects against HPV 6, 11, 16 and 18
Cervarix: protects against HPV 16 and 18

51
Q

When is the Gardasil vaccine given?

A

It is given to girls at 12/13 and 17/18. Only 2 doses are required. It protects against cervical cancer and genital warts.

52
Q

What is the gardasil vaccine made of?

A

It is a recombinant virus made of capside L2 proteins that acts as a virus like particle. It is very effective.

53
Q

When are pregnant women vaccined and why?

A

Vaccine the mother late during pregnancy, so she develops antibodies and passes them on to the babies. The baby will have immune protection for a short while, but it will protect them during this period.

54
Q

What are pregnant women vaccinated against?

A

Vaccinated for the child against neonatal tetanus. If given to the mother in late pregnancy, it means she will be vaccinated against the disease so will have high levels of maternal IgG in her body to pass to the neonate.

55
Q

What form is neonatal tetanus vaccine given?

A

Given in the form of toxoids not live because if live is given during pregnancy, damage to the foetus might occur.

56
Q

What is the tetanus vaccine given to pregnant women called?

A

Given a modified version of DTaP vaccine called Boostrix IPV that ensures the mother has high levels of antibodies to protect the baby

57
Q

Why are pregnant women also given the flu vaccine?

A

Flu in new-born babies can cause a serious infection and therefore it is very important to protect against.

SEM 4: Immunology (15 decks)

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