Vaccinology - Bacterial vaccines Flashcards
1
Q
What are the goals of bacterial vaccines? (5)
A
- Disease prevention
- Eradication & control of disease
- Protection of vulnerable populations through heard immunity
- Global health equity
- Prevention of antimicrobial resistance
2
Q
What are possible bacterial vaccine target antigens? (5)
A
- Bacterial DNA
- Flagella
- Lipopolysaccharides (LPS)
- Exotoxins
- Outer membrane proteins
3
Q
What type of bacterial vaccine types are available? (5)
A
- Toxoid
- Live attenuated
- Subunit
- Conjugate
- Inactivated
4
Q
For which bacterial diseases are toxoid vaccines used? (2)
A
- Diphtheria
- Tetanus
5
Q
What is the causative agent of diphtheria?
A
Corynebacterium diphtheriae
6
Q
How is diphtheria transmitted?
A
Respiratory illness, spreading via droplets
7
Q
What are the symptoms of diphtheria? (3)
A
- Pharyngitis
- Fever
- Swelling of the neck
8
Q
How does diphtheria cause severe respiratory disease?
A
Bacterial toxins kill respiratory tissue
9
Q
What is the untreated vs. treated mortality of diphtheria?
A
Untreated: 50%
Treated: 10%
10
Q
What is the causative agent of tetanus?
A
Clostridium tetani
11
Q
How is is tetanus transmitted?
A
From bacterial spores in the evironment
12
Q
What kind of toxin is tetanus toxin? What are its effects?
A
Neurotoxin, causing tightening of the muscles & brain damage
13
Q
There [is/isn’t] an antitoxin for tetanus
A
There is no antitoxin for tetanus
14
Q
What is the mortality of tetanus?
A
11%
15
Q
What is the mechanism of action of toxoid vaccines?
A
Combat the disease by generating antibodies to the toxins causing symptoms
16
Q
What is a toxoid?
A
Chemically-/heat-inactivated toxin
17
Q
What are the advantages of toxoid vaccines? (2)
A
- Highly effective
- Well-tolerated & safe
18
Q
What is the disadvantage of toxoid vaccines?
A
Slow manufacturing process -> requires bacterial culture & toxoid inactivation
19
Q
For which bacterial diseases are inactivated vaccines used? (4)
A
- Whooping cough
- Typhoid fever
- Cholera
- Plague
20
Q
What is the causative agent of whooping cough?
A
Bordetella pertussis
21
Q
What is the causative agent of typhoid fever?
A
Salmonella typhi
22
Q
What is the causative agent of cholera?
A
Vibrio cholerae
23
Q
What is the causative agent of plague?
A
Yersinia pestis
24
Q
Which two types of vaccine are available for Bordetella pertussis? Which one is used in the RVP?
A
- Whole cell vacine = inactivated vaccine
- Acellular vaccine = subunit vaccine -> used in RVP
25
Against which bacterial components is the immune response generated in inactivated vaccines?
All pathogen antigens
26
What are the advantages of inactivated bacterial vaccines? (4)
1. Stable
2. Cannot revert to virulent form
3. Safely adminstered to immunocompromised
4. Relatively inexpensive, can be mass-produced
27
What are the disadvantages of inactivated bacterial vaccines? (2)
1. Genreate less robust immune resposne -> may require boosters
2. Slow manufacturing process -> requires bacterial culture & inactivation
28
Which types of subunits can be used for subunit vaccines? (3)
1. Proteins
2. Peptides
3. Polysaccharides
29
Which bacterial subunits are included in the Bordetella pertussis acellular (=subunit) vaccine? (4)
1. Peractin
2. Pertussis toxoid
3. Fimbriae
4. Filamentous haemagglutinin
30
What are the advantages of bacterial subunit vaccines? (2)
1. Generally seen as the safest vaccine
2. No risk of recombination
31
What are the disadvantages of bacterial subunit vaccines? (4)
1. Lower immunogenicity
2. Usually requires adjuvants -> higher risk of side effects
3. Complex to develop
4. Polysaccharides are thymus-independent antigens
32
Why are subunit vaccins relatively complex to develop?
Requires discovery & production of target antigens
33
Why is it disadvantageous that polysaccharides are thymus independent antigens? (2)
They cause T-cell independent B-cell activation, leading to:
1. No immunity to polysaccharides in children
2. Poor memory induction
34
Why do children not develop immunity when vaccinated with polysaccharides?
T-cell independent antigen -> completely dependent on B-cells, which have not fully matured in young children
35
For which bacterial diseases are conjugate vaccines used? (3)
1. Haemophilus influenzae type B (Hib)
2. Pneumococcal disease
3. Meningococcal disease
36
What is the causative agent of pneumococcal disease?
Streptococcus pneumoniae
37
What is the causative agent of meningococcal disease?
Neisseria meningitidis
38
How many serotypes of Haemophilus influenzae are there?
6: a-h
39
What differentiates different Haemophilus influenzae-subtypes from one another?
Their capsular polysaccharides
40
Which of the Haemophilus influenzae-subtypes is considered most cangerous? Why?
Type b (Hib) -> can cause meningitis & sepsis
41
What is the case-fatality rate of Hib?
5%
42
What are frequent long-term consequences of Hib-infection? (2)
1. Neurologic sequelae: 10-15%
2. Deafness: 15-20%
43
How many pneumococcal serotypes are known?
>100
44
True or false: all pneumococcal serotypes can cause major infections
False; while most can cause disease, only a few can cause major infections
45
Which diseases can S. pneumoniae cause? (5)
1. Pneumonia
2. Bacteriaemia
3. Meningitis
4. Acute otitis media
5. Sinusitis
46
What is the case fatality rate of pneumonia caused by S. pneumoniae?
5-7%
47
What is the case fatality rate of bacteriaemia caused by S. pneumoniae in childeren vs. elderly?
20% in childeren, up to 60% in elderly
48
What is the case fatality rate of meningitis caused by S. pneumoniae in childeren vs. elderly?
8% in childeren, up to 22% in adults
49
Why are elderly vaccinated with a different pneumococcal vaccine than children?
Children = conjugated vaccine
Elderly = polysaccharide vaccine -> children's immune system poorly respond to polysaccharide vaccines
50
Which pneumococcal vaccine is used for children?
Synflorix = 10-valent conjugate vaccine
51
Which pneumococcal vaccine is used for elderly/immunocompromised?
Pneumovax 23-valent polysaccharide vaccine
52
How many serogroups of N. meningitidis are there? Which is considered most dangerous?
12 serogroups, group B is considered most dangerous
53
Which diseases can N. meniningitidis cause? (2)
1. Meningitis
2. Sepsis
54
What is the case fatality rate of meningitis caused by N. meningitidis?
5-10% (with good treatment)
55
What is the case fatality rate of sepsis caused by N. meningitidis?
20-50% within 24 hours
56
Which serogroups are included in the meningococcal vaccine?
A, C, W, Y
57
What kind of vaccine is the meningococcal vaccine?
Conjugate vaccine
58
To which conjugate are meningococcal antigens conjugated in the conjugate vaccine?
Tetanus toxoid
59
What is a bacterial polysaccharide? (definition)
Long polymer composed of repeating units of simple structures
60
Where are polysaccharides found?
On the outside of Gram+ and Gram- bacteria
61
What is the advantage of conjugation of polysaccharides to protein antigens?
Leads to T-cell activation, which in turn stimulates proper B-cell activation
62
What are the results of T-cell stimulation of B-cells in conjugate vaccines? (4)
1. B-cells properly activated -> antibody production
2. Limited memory formation
3. Hyporesponsiveness to subsequent vaccination
4. Still somewhat poor response in young children
63
What are the advantages of conjugate vaccines? (3) (compared to polysaccharide)
1. Enhanced immunogenicity
2. Protection of young infants
3. More effective immune response
64
What are the disadvantages of conjugate vaccines? (3)
1. Expensive
2. Resource-intensive
3. Limited strain coverage
65
For which bacterial diseases are live attenuated vaccines used? (2)
1. Oral typhoid vaccine
2. Tuberculosis
66
Are live attenuated vaccines currently in routine use in the RVP?
No
67
What are the two attenuation methods to create live attenuated bacterial vaccines?
1. Random/targeted mutations in virulence-related genes to weaken the bacterium
2. Use of less pathogenic strains/serotypes that are still similar to the disease-causing agent
68
What is the tuberculosis vaccine?
BCG vaccine
69
Which bacterial strain is used in the BCG vaccine?
Mycobacterium bovis -> provides cross-protection for severe tuberculosis disease
70
What are the advantages of bacterial live attenuated vaccines? (2)
1. More potent than inactivated vaccines
2. Immune response lasts longer
71
What are the disadvantages of bacterial live attenuated vaccines? (3)
1. Risk of reversion to disease-causing agent
2. Dangerous for immunocompromised
3. May require careful storage & transportation
