The scientific basis of vaccines Flashcards
1
Q
What is smallpox caused by?
A
variola virus
2
Q
What is variolation?
A
- used to be used in the olden days
- take healing lesions of smallpox
- take scabs of their skin
- inject people with them
- prevent other people from getting smallpox
3
Q
Why do you have to take a scab that was already healed?
A
- the virus has died
- antigen is there
4
Q
What is variola minor?
A
- mild version
- will recover
5
Q
What is variola major?
A
- causes death
6
Q
What other disease can prevent you from getting smallpox?
A
cowpox
7
Q
What did louis pasteur introduce the concept of?
A
- attenuation = change organisms from their disease causing state to those used in vaccines
8
Q
What are some principles from Jenner’s experiments?
A
- challenge dose of an organism leads to protection from infection
- attenuation (make organism weaker and less virulent) still causes immune response
- prior exposure of agent boosts immunity
- cross species protection and antigen similarity (i.e. using cowpox against smallpox)
9
Q
What were the reasons that made the eradication of smallpox easy?
A
- no subclinical infection
- once the disease is eradicated from the body, there are no carrier statuses (e.g. no asymptomatic shedding or reactivation)
- no animal reservoir- you cant get it from anywhere else in the environment
- there is an effective vaccine
10
Q
After a small pox vaccination, what does the scar look like?
A
- diff to BCG scar
- like a star
(bc they used sharp blade to inoculate the virus)
11
Q
What is a vaccine?
A
- material from an organism that actively enhances adaptive immunity
- boosts and enhances immunity to give protective immune response
12
Q
How is tetanus vaccinated against?
A
- tetanus is toxin mediated disease
(it is a gram positive rod which forms spores) - if you get it under your skin, it forms a neurotoxin
- the vaccination neutralizes the toxin
13
Q
What do vaccines mainly focus on?
A
- antibodies
- but there must be interaction between Th cells and B cells to get a right immune response
14
Q
What should a vaccine do?
A
- protect an individual from disease
- protect a population from disease
15
Q
What should the vaccine uptake rate balance with?
A
Reservoirs of infection
16
Q
What can cause a decrease in the number of vaccinations taken?
A
- if parents think that vaccines cause autism etc.
17
Q
What is the point of herd immunity?
A
- herd immunity is boosted by periodic outbreaks of diseases in the community
- we need to keep vaccine rates high bc there isnt any natural boosting
18
Q
What are the complications of measles?
A
- 1 in 15 children got secondary pneumonia, middle ear infections, bronchitis bc measles compromises the immune system
- 1 in 30 children could have serious consequences resulting in death
− 1 in 5000 children develop encephalitis (infection of the brain) with 15% mortality
19
Q
What are the side effects of the vaccines for measles?
A
- 1 in 1000 children got a fever or a compulsion
- 1 in 400,000 children develop meningoencephalitis which would go away with no harm what so ever
20
Q
What does diphtheria cause?
A
- upper respiratory tract inflammation
- bulging neck
- difficulty breathing
- 5% mortality
21
Q
What does the vaccine against diphtheria cause?
A
occasional swelling in the arm
22
Q
What does whooping cough cause?
A
- high mortality rates in neonates
- lots of coughing
- secondary bacterial pneumonia
- encephalopathy
23
Q
What does the whooping cough vaccine cause?
A
1 in 600,000 people get encephalopathy which heals itself without any problems
24
Q
What are the 2 types of immunity?
A
active
passive
25
What is active immunity?
- combination of B and T cells
| - long lasting memory
26
What is passive immunity?
- short term
| - giving antibodies
27
What are examples of passive immunity?
- concentrated formulations of antibodies:
- high titre against varicalla zoster virus
- horse serum with high ttre antibodies against tetanus= WW1- stop wound infections
- give mother who has hepB Ig against hepB to stop baby getting infection
28
Whathappens on the 1st exposure to an antigen?
1. get IgM
2. IgG
3. somatic maturation
4. High affinity IgG
5. memory B and T cells are laid down
29
Why cant you vaccinate against the flu or common cold?
- because if you vaccinate
- on secondary exposure, you get a rapid response that takes 2 days for a full immune response
- flu and common cold only take a few hours to cause disease
- so response wont be quick enough
30
What is an immuno-protective antigen?
on the surface of the vaccine
31
Give examples of intracellular organisms?
- shigella
- listeria
- Tb
- salmonella
32
How do you get rid of intracellular organisms?
- cant have antibodies for them because there is no point
| - needT cell type of immune response
33
Where does polio virus enter?
gut
| and then blood
34
What is used to get rid of polio?
IgA in gut
| IgG in blood
35
How do you get rid of yellow fever?
cytotoxic T cells
| antibodies for opsonization and phagocytosis
36
Where do parentral vaccines (not taken through GIT) have a good response?
good systemic response
37
Where do oral vaccines have a good response?
```
good mucosal response
producing IgA (bc antigens are processed by mucosa associated lymphoid tissue MALT)
```
38
Where does Bacterial Meningitis
–
H. Influenzae begin?
- starts off with nasopharyngitis
- then you get
- middle ear infections, bronchitis, secondary pneumonia, epiglottitis, and something called croup (inflamed bronchus cough)
39
What can bacterial meningitis lead to?
sepsis if it gets systemic
40
When is the incidence of haemophilus?
- in the first 2 years
- more age, less incidence
- the amount of antibody we need against it doesnt develop until ag of 2
- bc the main virulent component of the bacteria is polysaccharide capsule
- and we dont make antibodies for the capsule until 2
41
When do you give MMR vaccine?
- it is made of live attenuated viruses (weakened viruses)
- if give MMR to child being breastfed, the child has maternal antibodies which will neutralize against MMR
- and then when these antibodies wear off, the baby wont have immunization to MMR
- so give MMR vaccine at 1y/o when maternal antibodies have gone
42
How is polio vaccine given?
oral drop
43
What vaccines are given orally?
cholera
typhoid
rotavirus
44
What are the benefits of oral vaccinations?
- avoids needles
- mimics natural route of infection
- mucosal surfaces have large surface area- so large SA for MALT to detect antigens
- much better IgA protection
- allows better humoral immunity bc more lymphocytes are traficked to mucosal surfaces
45
What is a polytypic organism?
- e.g. influenza
- constant mutation of its surface
- so immune response against 1 strain wont protect you from another strain
46
What is a monotypic organism?
measles
47
What are the types of vaccines?
- live, attenuated organisms
| - killed whole organism
48
What are live attenuated organisms?
- alive
| - no longer virulent
49
Give examples of live attenuated organism vaccines?
- BCG which is based on mycobacterium bovis which causes bovine Tb
- the old polio oral vaccine has three live viral particles
- MMR are attenuated viruses
- yellow fever
- varicella zoster
50
What were the 3 types of polio vaccines?
- type 1 had 57 mutations done to it to make it avirulent (to make the virus weak)
- type 2 and 3 only had a few mutations that made it attenuated (weak)
some places type 2 and 3 could revert to wild type (infection causing)
- virus could be seen in babies nappies
51
What are examples of whole killed organism vaccinations?
- whooping cough virus (pertussis)
- old flu vaccine
- current polio vaccine
- cholera
- hepA
52
Which vaccine type needs to have boosters?
killed organism vaccine
- live attenuated vaccines can survive in the body for longer
- so you get continual exposure to antigens
- good immunoprotection from a single dose
53
What is a subunit vaccine?
based on proteins, inactivated toxins, peptides, or
| polysaccharide capsules on the outside of organisms
54
Why can polysaccharid capsules be a problem for babies to deal with?
- polysaccharide= poor antigens for children under the age of 2
- so conjugate polysaccharide with proteins
55
What is a DNA vaccine?
- inject a DNA that encodes for a certain antigen into a muscle
- DNA is transcribed and translated
- it makes a protein that stimulates an immune response
56
Which bacterial infections produce toxins?
- cholera
- tetanus
- botulism
- whooping cough
- diphtheria
57
What do we do to the toxins?
- purify the toxins, inactivate them forming a toxoid
- toxoids, are injected
- antibodies are made against them
- these antibodies will come and block the toxin should someone get infected by the organism
