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infection and immunity Flashcards

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1
Q

what is the definition of a pathogen

A

an organism capable of causing disease in humans

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2
Q

what are the 5 taxonomic groups of pathogens

A 
bacteria
virus
fungi
protozoa
helminths
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3
Q

what are fungi subdivided into

A 
divided into 
yeasts - binary fission
mycelia - dividing by septa
AND 
superficial - skin + nail infection
systemic - immunocompromised
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4
Q

what is a protozoa

A

single celled animals which causes disease as a result of the immune response divided into
intracellular / extracellular location

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5
Q

what are helminths

A

eukaryotic parasitic worms

  • tapeworms
  • roundworms -
  • flukes
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6
Q

name 5 ways a pathogen can enter the body

A 
skin - biting or needles 
inhalation - limited anatomical barrier 
GI tract - large and exposed surface area
urogenital - via urethra 
eyes - during childbirth
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7
Q

name the 2 forms of pathogen transmission

A

vertical / horizontal transmission

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8
Q

what factors are pathogen transmission dependant on

A

stability of pathogen outside host

number of organisms to infect a new host

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9
Q

describe vertical transmission

A

mother to fetus (placenta / breastfeeding / delivery)

rubella / Hep B / HIV

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10
Q

describe horizontal transmission

A

directly - close proximity

indirectly - contaminated food / water / blood

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11
Q

describe the shape of a coccus bacteria

A

SPERICAL

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12
Q

describe the shape of a streptococci bacteria

A

LONG CHAIN

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13
Q

describe the shape of a diplococci bacteria

A

IN PAIRS

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14
Q

describe the shape of a bacillus bacteria

A

ROD SHAPED

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15
Q

describe the shape of a staphylococci bacteria

A

CLUSTERS

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16
Q

describe the shape of a vibrio bacteria

A

COMMA SHAPED

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17
Q

describe the shape of a spirochetes bacteria

A

SPIRAL SHAPED

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18
Q

what does gram positive bacteria turn purple in crystal violet stain

A

THICK peptidoglycan layer that traps the stain

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19
Q

what does gram negative bacteria NOT turn purple in crystal violet stain and what is it alternatively stained with

A

THIN lipopolysaccharide outer layer so the purple stain washes off - safranin red counterstain

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20
Q

describe the steps of gram staining bacteria

A

1 add crystal violet stain
2 add gram iodine preticipate
3 add decolouriser ( alcohol) wash
4 add red counterstain

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21
Q

what is commensal flora

A

human microorganism SYMBIOTIC but can cause infection if enters the bloodstream / immuno compromised

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22
Q

what is an opportunistic infection

A

commensal flora / pathogen taking advantage of host due to immuno-compormised / wounds / hormonal changes / pregnancy

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23
Q

what is a healthcare associated infection

A

infection related to interaction with healthcare service - catheters / feeding tubes

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24
Q

what are bacterial virulence factors

A

molecules produced by bacteria that add to their effectiveness helping them to
1 invade host
2 cause disease
3 evade host defences

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25
name some bacterial virulence factors
``` adherence factors capsules endotoxins siderophores exotoxins antibiotic resistance ```
26
what do adherence factors do
use pili to adhere to cells at mucosal sites
27
what do capsules do
surround bacteria to protect them from phagocytosis
28
what do endotoxins do
on gram NEGATIVe bacteria leading to fever / inflammation / shock
29
what do siderophores do
iron ion binding factors to compete with host
30
what do exotoxins do
enzymes secreted - cytotoxins
31
what are the features of a virus
metabolically inert contains DNA/RNA genome surrounded by a capsid
32
what are the main features of the lytic cycle
results in destruction of the infected cell and its membrane
33
what are the main features of the lysogenic cycles
results in integration of pathogen nucleic acid into host genome of cell
34
describe the steps of the lytic cycle
1 phage attaches / penetrates host cell 2 phage DNA arcularius 3 phage DNA replicates / makes proteins 4 new phage particles are produces 5 cell lyseses and releases new phages
35
describe the steps of the lysogenic cycle
1 phage infects cell 2 biosynthesis of viral RNA / phage DNA incorporates into host genome 3 cell divides / prophage DNA passed to daughter cells 4 stressful cellular conditions = enters stage 3 of lytic
36
what is sense (+) in the Baltimore classification of viruses
used directly as mRNA to translate viral proteins
37
what is antisense (-) in the Baltimore classification of viruses
complimentary RNA strand has to be produced in host cell to be used as mRNA
38
what are the 4 types of cellular level viral infection
acute / lytic persistent / chronic latent / proviral transforming
39
describe an acute / lytic cellular level viral infection
rapid host death
40
describe a persistent cellular level viral infection
long term with low levels of virus production
41
describe a latent / proviral cellular level viral infection
viral genome maintained within host
42
describe a transforming cellular level viral infection
virus produces altered cell growth
43
name 3 viruses that are linked with cancer
Hep B human papilloma epstein barrvirus
44
name the 6 components of INNATE immunity
``` macrophages dendritic cells mast cells neutrophils basophils natural killer cells ```
45
describe the function of a macrophage
key sentinel cell in peripheral tissue
46
describe the mechanism of a macrophage response
1 sense pathogen with PATTERN RECOGNISING RECEPTORS 2 communicate detection of pathogen with INFLAMMATORY CYTOKINES (IL1 /6/12 and TNF alpha) 3 macrophages perform phagocytosis
47
what is the effect of IL 1 and TNF alpha release
capillary dilation | increase endothelial wall permeability
48
what is the function of a dendritic cell
similar to macrophage in peripheral tissue
49
where to dendritic cells migrate to from the infection site
lymphatic vessels | present peptide complexes to TCR (t cell receptor) on T native T cells
50
where are mast cells found
connective tissue
51
what does mast cell activation entail
release of HISTAMINES / PROSTAGLANDINS leading to vasodilation
52
where are neutrophils found
the blood
53
when can neutrophils enter an infection site
when vessels have increased permeability
54
what do neutrophils perform efficiently
phagocytosis
55
what to basophils protect against
protozoa / helminths
56
where are natural killer cells found
blood | peripheral tissue
57
what does PAMP stand for
pathogen associated molecular patterns
58
what are PAMPs
component of pathogen which allows recognition from host components
59
what recognises PAMPs
PRR - pattern recognition receptors
60
name a PRR
TLR | toll-like receptors which are expressed by B cells / macrophages / NK cells and dendritic cells
61
What is the function of a TLR
SIGNALLING | 10 receptors with variable specificity
62
what function do macrophage receptors perform
phagocytosis targets bacteria targets mannose receptors with ligand activation
63
where are TLR 4 / 5 located in the body
``` plasma membrane (extracellular) endosome ```
64
what is the cascade activated by these TLRs when bacteria / fungi are detected
1 transcriptional factor activation 2 TNF alpha / IL 1 / 6 expressed 3 co-stimulatory receptor ligands expressed B7 1 and 2
65
where are TLR 3 / 7 /8 / 9 located
intracellular in endosomal compartment
66
what is the cascade activated by these TLRs when viruses are detected
signalling production of cytokines
67
what are the 3 locations of entry and un-coating for bacteria
plasma membrane within endosome at nuclear membrane
68
what are the 3 key soluble components of innate immunity
antimicrobial peptides compliment proteins cytokines
69
describe the overall steps of the compliment system
1 alternative / classical / lectin pathway 2 terminal pathway 3 C5a formation and membrane attack complex
70
describe the classical pathway
1 IgM / IgG binds to pathogen 2 this is recognised by 1st component of compliment C1 and follows a cascade to form C3b
71
describe the lectin pathway
1 mannose residue on pathogen is recognised by mannan binding lectin 2 C3b is produced via production cascade
72
describe the alternative pathway
1 auto-activation of C3 that occurs on the surface of the pathogen
73
when is the alternative pathway the most important
early infection
74
what function does C3b serve (steps)
1 covalently binds to pathogen surface 2 flags pathogen to phagocytes that have a C3b receptor 3 OPSONISATION 4 terminal pathway activation = C5a formation
75
what is OPSONISATION
pathogen is chemically modified to be more attractive to phagocytes / NK cells
76
what is the function of C5a (generalised)
strong chemoattractant and is involved in the recruitment of inflammatory cells such as neutrophils, eosinophils, monocytes, and T lymphocytes, in activation of phagocytic cells and release of granule-based enzymes and generation of oxidants
77
what are the steps of opsonisation
overall = C3b fixation to pathogens (particularly bacteria) 1 CR1 / 3 receptors recognise C3b fixation 2 phagocytosis (++ efficiency) 3 intracellular killing
78
what happens if there is a C3 component deficiency within the body
more susceptible to bacterial infection
79
what is C5a anaphylatoxin
a chemotactic agent (chemoattractant)
80
describe the steps of C5a anaphylatoxin mechanism
1 attracts neutrophils / macrophages 2 enhances neutrophil phagocytosis ability 3 VASODILATION / increased permeability 4 degranulation of mast cells / basophils / muscle contraction 5 INFLAMMATION
81
describe the process of degranulation
release of antimicrobial cytotoxic or other molecules from secretory vesicles called granules
82
describe the process of forming the membrane attack complex
C5b C5b7 MAC - cell lysis and membrane lesions
83
what is the function of the MAC
creates pores in the pathogen surface membrane allowing lysozymes to enter and destroy the protective cover - particularly effective against gram negative bacteria
84
what facilitates the changing of membrane phospholipids into prostaglandins
IL-IB | TNF alpha
85
what is the function of prostaglandins
- inflammation - reduced pain threshold - fever
86
what is the outcome of IL-6 conc. increase
fever | hepatocyte inflammation
87
what is the outcome of TNF alpha conc. increase
increased vascular permeability fever shock
88
what is the outcome of IL-1/3 conc. increase
fever IL-6 production lymphocyte activation
89
what is the outcome of CXCL 8 conc. increase
basophil / neutrophil recruitment
90
what is the outcome of IL-12 conc. increase
activates natural killer cells
91
when is adaptive immunity initiated
when the innate immunity becomes overwhelmed
92
describe the clonal selection hypothesis
1 many individual different lymphocytes 2 pathogen binds to unique receptor + activates it 3 mytotic expansion - daughter cells express same receptor 4 body gives rise to effector cells that eliminates pathogen
93
where is the lymphocyte initially activated
draining lymph node
94
what cell brings the pathogen component to the lyphocyte
dendritic cell
95
where are t cell receptors find
trans-membrane NOT SECRETED
96
what is the function of processing and presenting pathogen antigens
recognising infected host cells
97
describe the steps involved in antigen processing / presentation
1 pathogen invades host cell 2 protein from pathogen binds to MHC 3 presented on cell surface of infected cells 4 recognised by TCR on T cell surface
98
what does MHC stand for
major histocom patibility complex
99
where are MHC class 1 found
all nucleated cells
100
where are MHC class 2 found
exclusive to - b cells - macrophages - dendritic cells
101
what are CD8+ cells and what is their function
killer T cells | directly kills infected cells
102
what are CD4+ cells and what is their function
helper T cells | provides assistance to other immune system cells by secreting cytokine activating macrophages / B cells
103
what are immunoglobulins a secreted form of
B-cell antigen receptor
104
what are immunoglobulins made up of
glycoproteins | 4x chains 2x heavy 2x light
105
how many antigen binding regions are there on an immunoglobulin
2
106
what is somatic rearrangement
multiple encoding domains which randomly rearrange DNA / imprecise chain joining to allow immunoglobulin diversity
107
what immunoglobulin are all others rearranged forms of
IgM
108
describe the process of class switching
modification of the heavy chain of an immunoglobulin to produce different classes (types) from IgM
109
what function do IgM perform
neutralisation compliment system activation epithelium transport
110
what function does IgD perform
basophil sensitisation
111
what function does IgA perform
neutralisation oponization compliment system activation extravascular diffusion
112
what function does IgE perform
mast cell sensitisation | extravascular diffusion
113
basophil / mast cell function
release of inflammation / allergic response chemicals
114
neutrophil function
ingest / destroy pathogens
115
eosinophils function
destroy pathogens (particularly antibody coated ones)
116
monocyte / macrophage function
antigen presentation / ingest pathogens
117
lymphocyte / plasma cell function
specific response to pathogens / antibody production
118
dendritic cell function
recognise pathogens and activate other immune cells by antigen presentation in lymph nodes
119
name the cellular components - innate immunity
``` macrophage natural killer cells dendritic cells neutrophils eosinophil basophil T cell Natural killer T cell ```
120
name the cellular components - adaptive immunity
B cell T cell - CD4+ / 8+ Natural killer T cell Antibodies

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