Lecture 16 Host Microbe Interactions Flashcards
(112 cards)
1
Q
Symbiosis
A
Living together
2
Q
Mutualism
A
Both partners benefit
3
Q
What kind of symbiosis is this:
In large intestine, some bacteria synthesize vitamin K and B which host can absorb, bacteria are supplied with warmth, energy source
A
Mutualism
4
Q
Commensalism
A
One partner benefits, other is UNHARMED
5
Q
Parasitism
A
One organism benefits, other is HARMED
6
Q
microbiome is different after what births?
A
Vaginal birth, caesarian birth
7
Q
Dysbiosis
A
Imbalance in microbiome
8
Q
Dysbiosis can be _____ induced
A
Antibiotic
9
Q
Main benefit of microbiome
A
Protection against pathogens
10
Q
When microbiome is suppressed (during antibiotics), pathogens may _____, cause disease
A
Colonize
11
Q
Antibodies against normal microbiota may also bind to _____
A
Pathogens
12
Q
Colonization
A
Microbe establishing itself and multiplying
13
Q
Infection
A
Colonization of pathogen
14
Q
Infection can be _____ or _____
A
Subclinical, infectious disease
15
Q
Subclinical
A
No symptoms or mild symptoms
16
Q
Infectious disease
A
Prevents normal function, damages host
17
Q
Difference between infection and disease
A
Infection: First step, occurs when pathogen enters body and begins to multiply
Disease: cells in body are damaged as a result of infection, symptoms appear
18
Q
_____ are subjective effects experienced by patient
A
Symptoms
19
Q
_____ are objective evidence that can be observed/measured
A
Signs
20
Q
Initial infection is called _____
A
Primary infection
21
Q
Damage can predispose individual to developing a _____ infection
A
Secondary
22
Q
Pathogenicity
A
Ability of pathogen to cause disease
23
Q
Primary pathogen
A
Microbe that causes disease in otherwise healthy individual
24
Q
Opportunistic pathogen
A
Microbe causes disease only when immune system is compromised
25
Virulence
Degree of pathogenicity
26
Virulence factors
Substances that allow microorganism to cause disease
27
Communicable disease
easily spread from one host to another
28
infectious dose
number of microbes necessary to establish infection
29
What does ID 50 mean?
Number of cells required to infect 50% of test animals
30
Incubation period
Time between infection and onset
31
Illness
Signs and symptoms of disease are prevalent
32
Prodomal
Vague symptoms
33
Convalescence
Recuperation, recovery from disease
34
Acute infections
Symptoms develop quickly, last a short time
35
What type of infection is strep throat
Acute infection
36
Chronic infection
Develop slowly, last for months or years
37
Latent infections
never completely eliminated, microbe exists in host tissues without causing symptoms
38
Chickenpox and tuberculosis are what type of infection
Latent infections
39
Staphylococcus is what type of infection
Localized
40
Systemic infection
Agent spread throughout body
41
Bacteremia
Bacteria circulating in blood
42
_____ leads to sepsis
Bacterermia
43
Toxemia
Toxins circulating in blood
44
Viremia
Viruses circulating in blood
45
Koch's postulates
Microorganism must be present in every case of disease
organism must be grown in pure culture from diseased host
Same disease must be produced when pure culture is introduced into susceptible hosts
organisms must be recovered from experimentally infected host
46
Limits of koch's postulates
Some organisms can't be grown in laboratory medium
infected individuals do not always have symptoms
Suitable animal hosts not always available for testing
humans may be only affected host species
47
Molecular koch's postulate
modern day version that takes into account limitations
Virulance factor gene is identified
mutating gene in vitro to disrupt function should reduce virulence
reversion or replacement of gene should restore virulence
can test on an appropriate animal model of infection
48
Pathogens and hosts generally evolve towards _____
Balanced pathogenicity
49
Balanced pathogenicity
Pathogen becomes less virulent while host becomes less susceptible
50
Adherence
Adhesions attach to host cell receptor
51
Adhesions are located where
Tips of fimbrae
52
What is the binding of adhesions
Highly specific
53
What happens after adhesion
Colonization and establishment of disease
54
colonization and establishment of disease
microbe may produce _____ to bind iron
competes with _____, _____ of host
Siderophores
lactoferrin, transferrin
55
colonization and establishment of disease
Microbe must avoid _______
rapid pili turnover, antigenic variation _______
secretory IgA
IgA protease
56
Establishing an infection steps
Adherence
Colonization
Immune avoidance
Damage to host
Exit and infect new host
57
delivering effector proteins to host cells
secretion systems in some gram _______
Gram negatives
58
Delivering effector proteins in host cells
What type of secretion system
Type III
59
effector proteins induce changes in _______
Cytoskeleton structure
60
Pathogen induces _______ cells to engulf them via endocytosis
Non phagocytic
61
Actin molecules in host cells rearrange, causing _______
membrane ruffling
62
What is the entry point for most pathogens
Mucous membrane
63
What process happens in mucous membranes
Exploiting antigen sampling processes
64
in EASP, _______ samples material
MALT
65
hiding within a host cell allows what?
avoidance of complement proteins, phagocytes, antibodies
66
shigella directs transfer from intestinal epithelial cell to adjacent cells by causing host cell _______
actin polymerization
67
What prevents encounters with phagocytes?
C5a peptidase
68
What does C5a peptidase do?
degrades chemoattractant C5a
69
What does membrane damaging toxins do?
kill phagocytes, other cells
70
s. pyogenes makes _______
Streptolysin O
71
Avoiding recognition and attachment
capsules interfere with _______, some bind host's regulatory proteins that inactivate _______
Opsonization, C3b
72
M protein
Cell wall of S. pyogenes that binds regulatory protein that prevents C3b inactivation
73
Fc receptors
bind Fc region of antibodies, interfering with their function as opsonins
74
What bacteria makes Fc receptors
S. Aureus
75
Surviving within phagocytes allows pathogens to
Avoid antibodies, control immune responses, move throughout body
76
escape from phagosome is prior to
lysis with lysosome
77
Escape from phagosome:
Some pathogens escape phagosome before it fuses with lysosomes. The bacteria then multiple within cytoplasm and
78
Preventing phagosome-lysosome fusion:
avoid destruction
79
Survive within phagolysosome
Few can survive destructive environment in phagolysosome
80
serum resistant bacteria: organism binds complement regulatory proteins to avoid _______
MAC
81
Avoiding recognition by antibodies
_______ cleaves IgA
found in mucus, secretions
IgA protease
82
Antigenic variation
Alter structure of surface antigens, stays ahead of antibody production
83
Mimicking host molecules
Cover surface with molecules similar to those found in host cell, appear to be "self"
84
Direct effects
Toxins produced
85
Indirect effects
Immune response
86
Damage may help pathogen to_______
Exit and spread
87
Exotoxins
Proteins with specific damaging effects
88
Exotoxins are secreted into tissue following _______
Bacterial lysis
89
Most exotoxins destroyed by
Heating
90
Toxoids
Inactived toxins
91
Antitoxin
Suspension of neutralizing antibodies
92
Neurotoxins
effect nervous system
93
Enterotoxins
Cause intestinal disturbance
94
cytotoxins
Damage variety of cell types
95
A-B toxins
A subunit is toxic/active
B subunit binds to target cell
96
What subunit determines cell type to be infected?
B subunit
97
Membrane damaging toxins
Cytotoxins that disrupt eukaryotic cytoplasmic membranes, lyse cells
98
Pore-forming toxins
insert into membranes, form pores
99
What is a pore forming toxin
Streptolysin O from streptococcus pyogenes
100
Phospholipases
Hydrolyze phospholipids of membrane
101
What is a phospholipase
A-toxin of clostridium perfingens
102
Superantigens
Stimulate high number of Th cells, causing Cytokine stork
103
Superantigens simultaneous bind _____ and _____-
MHC class II and T cell receptor
104
Toxic effect is from ______
massive cytokine release
105
Many antigens undergo ______ after superantigens, thereby suppresing the immune system
apoptosis
106
Endotoxin is a ______ found in outer membrane of gram ______ cell wall
LPS, negative
107
______ triggers inflammatory response
lipid A
108
When lipid A is systemic, causes widespread response, ______
Septic shock
109
______ is heat stable
Lipid A
110
______ detects endotoxin
Limulus amoebocyte lysate
111
Exotoxins from both gram negatives and positives are ______
potent, heat inactivated
112
Endotoxins from gram negatives are ______
heat stable
