Pathogens Flashcards
(134 cards)
1
Q
Which one is the more virulent ?
S. pneumonia or Salmonella enterica serovar Typhimurium
A
S. pneumonia
2
Q
Virulence is determined by 2 principal features
A
1- invasiveness
2- Toxigenicity
3
Q
What is a pathogen?
A
Microorganisms capable of causing disease (damage to the host)
4
Q
Does all strain of a specie have the same virulence properties?
A
No
Not all strains of a specie have the same ability to cause disease
5
Q
True or false:
A pathogen is usually identified by the set of chromosomes that are carried and expressed?
A
False
6
Q
True or false:
A pathogen is usually identified by the set of virulence genes that are carried and expressed?
A
true
7
Q
Steps of infection
A
1- exposure
2- attachment-adhesion
3- invasion of tissues
4- Grow
8
Q
Describe virulence:
A
Measure of the ability to cause damage to the host, depends on a number of virulence factors
9
Q
invasiveness tools:
A
Adhesins capsules enzymes that destroy host tissues invasins T3SS T4SS
10
Q
Are capsules only produces by bacterial pathogens?
A
No
The capsule is not only a virulence factor (non pathogenic microorganisms may have a capsule too)
11
Q
What is invasion?
A
Destruction of host tissues
12
Q
Gas gangrene : 3 extracellular enzymes
A
1- lecithinase to lyse host cell
2- Collagenase
and 3- hyaluronidase to destroy ECM
(both collagenase and hyaluronidase destroy ECM)
13
Q
Hemolysin : some are cytolysin (do what)
and some are enzymes (lechithinase, phospholipase) (do what)
A
Cytolysin : pore forming
Lecithinase : degrade lecithin ( phosphatidylcholine) in cell membrane - cause the lysis of red blood cells and destroys tissues cell.
14
Q
What is the major virulence factor of intracellular pathogens?
A
Invasins
15
Q
T3ss also called…
A
injectosome
16
Q
TXSS have a needle like structure
A
T3SS
17
Q
Pneumonia : infection or intoxication
A
infection
18
Q
Meningitis: infection or intoxication
A
infection
19
Q
syphilis: infection or intoxication
A
infection
20
Q
food poisonin: infection or intoxication
A
intoxication
21
Q
AB toxin: Exotoxin or endotoxin
A
Exotoxin
22
Q
extracellular enzymes (hyaluronidase, collagenase).. : Exotoxin or endotoxin
A
Exotoxin
23
Q
A subunit?
A
Enzymatic subunit
24
Q
B subunit?
A
Binding-cell entry
25
This subunit modifies a target inside the host cell leading to damage to the host
A
26
Botulinum toxin : Exotoxin or endotoxin
exotoxin
27
Cholera toxin: Exotoxin or endotoxin
exotoxin
28
What is botox used for? (3)
- reduces wrinkles-frown
- muscle spasms
- Hyperhydrosis (excessive sweating)
29
AB toxin : Botulinum toxin
| This neurotoxin blocks...
acetylcholine release in neurmuscular junction
| = Flaccid paralysis
30
AB5 toxins : Cholera toxin
| Subunit A : ??
Adenylate cyclase, produce cAMP
31
Endotoxin describe it (at least 3 characteristics)
- Lipid A of LPS from Gram - bacterial pathogens. Released during multiplication or lysis of bacterial cells.
- Heat stable
- Weakly immunogenic (no antibody are produced against LPS).
- Very effective activator of the immune system, produce general systemic effect: fever (pyrogenic), shock, weakness, inflammation, diarrhea, SEPTIC SHOCK
- important cause of symptoms in all Gram-bacterial infections (Salmonella, E.coli).
32
Extremely potent, amongst the most lethal substances known
Exotoxins
33
How do you call a toxin that is inactivated by formaldehyde or heat
toxoid
34
True or false
Endotoxins cannot be activated by heat or formaldehyde and cannot be converted to a toxoid : no vaccine against endotoxins.
True
35
True or false
| Exotoxins do not produce fever in host
true
36
True or false
| Endotoxins do not produce fever in host
false
37
True or false
| Mode of action of exotoxin: fever diarrhea vomiting
false
38
True or false
| Mode of action of endotoxin : fever diarrhea vomiting
true
39
True or false
| Exotoxin are highly immunogenic
true
40
True or false
| Endotoxin are weakly toxic, rarely fatal
true
41
True or false
| Exotoxins are heat-labile
true
42
True or false
| Endotoxin are heat-labile
false
43
Innate defense are specific or not
non-specific
44
Adaptive defense are specific or not
yes specific.
| based on antigens
45
Normal microbiome secrete...
bacteriocin
46
what are some antimicrobial substances: (4)
1- Fatty acids
2- lysozymes
3- antimicrobial peptides (AMPs)
4- antibodies (if the host is immune)
47
innate defense of the skin?
Thick layer of dead cells
48
Innate defense of the mucous membrane?
mucous
49
What are phagocytes?
Cells that take up and digest pathogens
50
inflamation is due to innate system or specific system against a host
innate system
51
What is the complement system?
set of proteins that creates pore in the pathogen membrane and induce lysis
(part of the second line of defenses)
52
Name all the proteins of the complement system
```
C1
C2
C3
C4
C5
C6
C7
C8
C9
```
53
What activate the classical pathway
antibodies
54
what activate the alternative pathway
microbial cell wall components (polysaccharides,lipopolysaccharides)
55
What happen when the complement is activated?
formation of a membrane attack complex (MAC, made of proteins C5b6789)
56
what happen when MAC is formed?
lysis of some Gram -, no effect on gram +
57
What is serum sensitivity?
test sensitivity to complement by exposing pathogens to serum (blood without RBC)
58
Name 2 cells made from Monocytes
Dendritic cell
| Macrophage
59
Name 3 White blood cells
1- Monocyte
2- Granulocyte
3- Lymphocyte
60
What are the 4 steps of phagocytosis
1- Attachment of the organism to the membrane of the phagocyte
2- Ingestion : the organism become enclosed in a phagosome
3- A) Granules (endosomes, lysosomes) containing hydrolytic enzymes fuse with the phagosome, formation of the phagolysosomes.
B) Oxidative burst : production of reactive oxygen species ( ROS)
4. Killing and digestion of the microorganism
61
Phagocytosis is carried primarily by 2 types of cells
Neutrophils (WBC) and macrophages (WBC)
62
Characteristics of Inflammation, name a few
- Redness
- heat
- swelling
- pain
63
What is the function of inflammation
bring immune cells, antibodies, complement subunits
64
What does IL1 do
1- acts on the thermoregulatoy center of the brain
2- activates phagocytes and other cells of the immune system
3- make inflammation happen
65
Name some innate defenses
- complement
- antimicrobial proteins
- phagocytes (neutrophils, macrophages)
- Inflammation
66
leucocidin purpose
1kill white blood cell (leucocyte)
| -pore forming toxin
67
extracellular enzyme to invade?
collagenase
68
purpose of T3SS
- insert protein into the host
- invasiveness
- take control of the host cell
69
whats in a lyzozome
- hydrolytic enzymes
| - antimicrobial peptides
70
example of phagocyte
- macrophages
| - neutrophiles
71
Mast cells are involved in
inflammation
72
What are the proteins of the complement that forms the MAC complex
-C123456789
-c1t o c4 are important for activation of the complement
C5 to C9 forms the MAC complex
73
2 ways to activate the complement
1- alternative pathway
LPS or surface proteins
2- classical pathway
by antibodies
74
Phagocytosis steps (4)
```
1- attachment
2- ingestion
3- formation of the phagolysosome
Oxidative burst: ROS production
4- Killing and digestion of the microorganism
```
75
Set of proteins of the innate system
complements
76
Macrophage secretes
cytokine (hormone, signaling molecule) : interleukin-1
77
Mast cells senses
pathogens
78
Il-1 causes ... to the blood vessel
vasodilatation
79
what is pyogenic
fever
80
What acts on the thermoregulatory center of the brain
Il-1
81
Innate defenses (4)
1- complement
2- antimicrobial proteins
3- phagocytes (neutrophils, macrophages)
4- Inflammation (and fever)
82
```
Adaptive defenses
What cells (3)
```
1- B cells
2- T cells
3- antigen presenting cells (APCs : macrophage, dendritic cells)
83
Adaptive defense
| 3 characteristics
1- Specificity
2- Memory
3- Tolerance
84
T cells and B cells recognize billions of antigens
| What concept?
Specificity
85
Making copies
| What concept?
Memory
86
immune cells recognize and react with individual molecules(antigens) via direct molecular interactions
what concept?
Specificity
87
The immune response to a specific antigen is faster and stronger upon subsequent exposure because the initial antigen exposure induced growth and division of antigen-reactive cells, resulting in multiple copies of antigen-reactive cells.
What concept?
Memory
88
2 types of T cells
T helper cells
| Cytotoxic T cells
89
MHC II expressed by (2)
APCs
| B cells
90
MHC 1 expressed by which cells?
All cells
91
MHC1 recognized by
cytotoxic T cells
92
MHCII recognized by
helper T cells
93
macrophage has which MCH
MHCI and MHCII
94
APCs present antigen to T cells
| Activated T cell produce
Il2
95
APCs include (3)
- macrophages
- dendritic cells
- B cells
96
Most important APCs for the process of presenting antigens to helper T cells (2)
- macrophages
| - dendritic cells
97
Helper t cells activated do 2 things
clone (memory)
| effector (join the fight)
98
Cytokine secreted by
T H cell
99
Perforin and granzyme are released by
T C cells
100
MHC 1 is related to which cell
Cytotoxic T cells
101
Activation of macrophages
When Th cell is activated,
it can activates macrophage by producing ...
TNF-alpha
102
What are called activated macrophages by TNF-alpha?
Angry killer cells
103
picked up by phagocytosis
| loaded by MHC..
MCH2
104
If the antigen is present in the cytoplasm of the host cell, it can be loaded by MHC..
MHC1
105
what is Fab
Antigen binding sites that are highly variable
106
What does the Fc (constant region) activates?
Complement (classical pathway)
107
B cells are phagocytic
| display antobodies on its surface by MHC..
MHC 2
108
processed on a phagosome MHC...
MHC2
109
B cell multiplies and differentiates into (2)
Plasma cells
| memory cells
110
Activated T cell bind to the antigens
| Helper T cell secretes
Il-4
| clue for the b cell to get activated
111
What is a clue for the b cell to get activated ?
Il-4
112
When B cell is activated what does it do
makes clones of himself
| clones= plasma cell or memory cell
113
Plasma cell (short lifetime) secretes
antibodies
114
A molecule that enhances phagocytosis by marking an antigen for an immune response is known as
Opsonin
115
Antibody binds to
toxin
116
What are hemolysins
some are enzyme (lecithinase, phospholipase)
| some are cytolysin (pore-forming)
117
Capsule is an essential virulence factor for 2 bacterial pathogens
Streptococcus pneumoniae
| Haemophilus influenzae
118
Lecithinase degrades lecithin(phosphatidylcholine)
| cause the lysis of
red blood cells
| and destroys tissue cells
119
Leucocidin causes lysis of
leucocytes (white blood cells)
120
Proteases degrade
complement proteins and or antibodies
121
Which type of secretion system forms a channel through the bacterial cytoplasmic membrane, the periplasm, the outer membrane, and the host cell membrane ?
T3SS
122
___toxins are secreted into the surrounding as the bacterial pathogen grows
Exotoxin
123
__toxins are part of the bacterial pathogen
Endotoxin
124
I am among the most lethal substance known
Exotoxin
125
High cAMP makes a change in the cell and it stops picking up...
Sodium
126
Weakly immunogenic, Exo or Endo?
Endotoxins
127
Vaccines are against Exo or Endo?
Exotoxins
128
inactivated toxin is aka
toxoids
129
AMPs make ____ pores in the bacterial membrane
Pores
130
What is inflammation?
general nonspecific response of the innate system to toxins, pathogens and tissue damage
131
Complement system complement the action of
antibodies
132
What is the precursor of T and B cells
Lymphoid precursor
133
Name 3 WBC
Monocytes
granulocytes
lymphocytes
134
Name 2 T cells
T helper cells
| cytotoxic T cells
