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FBS2 > Immunity and Infection > Flashcards

Immunity and Infection Flashcards

1
Q

What is the innate immune response?

A

Non specific defence mechanism

Host uses immediately/within several hours after exposure to antigen

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2
Q

What are 4 characteristics of the innate immune response?

A

Born with it
V fast
Responds same way each time
Induces + directs acquired/adaptive immune response

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3
Q

What enzyme is in tears, sweat and saliva that protects body and what does it do?

A

Lysopzyme

Destroys bact walls

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4
Q

What antibacterial compound does the skin produce and what bact is it active against?

A

Psoriasin

E coli

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5
Q

What is primary cilia dyskinesia?

A

Can’t make cilia/ cilia x move

Recurrent lung infections

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6
Q

What is PAMP?

A

Pathogen Associated Molecular Patterns

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7
Q

What 2 features must PAMP have?

A

Present in microorganism, x host

Essential to survival of pathogen

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8
Q

What is the PAMP in:

a) Gram negative bacteria?
b) Gram positive bacteria?

A

a) Lipopolysaccharide (LPS) in cell wall

b) Lipoteichoic acid in cell wall

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9
Q

What is PRR?

A

Pattern Recognition Receptor

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10
Q

What are the 3 types of PRR?

A

Collectins
Toll-like receptors
Nod-like receptors

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11
Q

What are 2 regions of collectins?

A

Collagen like region - interacts effector prts immune system

Lectin region - binds sugar molecules on surface of pathogen e.g. mannose

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12
Q

What do these toll-like receptors recognise?

a) TLR 3
b) TLR 5
c) TLR 9

A

a) Double stranded RNA
b) Flagellin in bact
c) Unmethylated CpG DNA in bact

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13
Q

What does NOD stand for?

A

Nucleotide Oligomerization Domain

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14
Q

Where are complements synthesised and when?

A

Liver

In response to inflammation

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15
Q

What is the key complement protein and what enzyme activates it?

A

C3

C3 convertase

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16
Q

What are 3 ways complements are activated?

A

Classical
Alternative
MB-lectin

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17
Q

How are the 3 complement activating pathways triggered?

A

Classical - antigen-antibody complex
MB-lectin - mannose residue on pathogen
Alternative - pathogen spontaneously activates

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18
Q

What molecules are formed from the cleavage of C3?

A

C3a - smaller

C3b - larger

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19
Q

What does C3a do?

A

Diffuse away from site of infection
Binds C3a receptor in macrophage + neutrophils
Recruits them to site of infection

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20
Q

What does C3b do?

A

Coats pathogen - opsonization

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21
Q

What is the MAC and what does it do?

A

Membrane Attack Complex

Makes pore that inserts ==> bact cell wall, destroy by lysis

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22
Q

What protein is MAC activated by?

A

C3

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23
Q

What is the difference between macrophage and monocyte?

A

Monocyte - In bloodstream

Macrophage - In tissue

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24
Q

Name 3 features of monocytes/macrophages

A

Mature from circulating monocyte
Large no in GI tract, lung, liver, spleen
Relativ long lived

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25
Q

Name 2 features of neutrophils?

A

Only in blood

Short lived

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26
Q

What reactive intermediates are in neutrophils and what are they involved in?

A

O2 intermediates

Respiratory burst

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27
Q

What enzyme reduces O2 to make O2 radicals?

A

NADPH oxidase

Form hydroxyl radicals + hypochlorite

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28
Q

What is the effect of reactive O2 and N2 intermediates on bacteria?

A

DNA damage + alterations to bacterial membranes

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29
Q

Why are O2 radicals regulated and how?

A

X specific to bacterial cells so can damage host cells

Rapid conversion to harmless products

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30
Q

What reactive intermediates are in macrophages?

A

N2 intermediates

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31
Q

Equation for formation of NO radicals + enzyme?

A

O2 + L-arginine ==> L-citrulline + NO radicals

NO synthase

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32
Q

What are the most potent activators of NO synthase?

A

Interferon gamma

Tumour necrosis factor

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33
Q

What molecules do cytokines activate in the innate immune response?

A 
IL-1 (interleukin 1)
IL- 6 (interleukin 6)
TNF alpha (turnover necrosis factor alpha)
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34
Q

What is the role of chemokines?

A

Promote inflammation by enabling cells to adhere to surface of blood vessels + migrate to infected tissue

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35
Q

What are the 2 type 1 interferons and when are they produced?

A

IFN alpha
IFN beta
Produced in response to virally infected cells

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36
Q

What does pleiotropic mean in context of chemokines?

A

When 1 chemokine receptor can bind >1 chemokine

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37
Q

Name 3 features of natural killer cells?

A

Kill virally infected cells + tumour cells
Response to TNF alpha, IL-12
Produce IFN gamma

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38
Q

Name 2 functions of critical cytokines

A

Activate macrophages

Upregulate MHC molecules

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39
Q

What do critical cytokines do with IL-12?

A

Stimulate differentiation of CD4 Th1 cells

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40
Q

What are the antigen presenting cells in body?

A

Macrophages
B cells
Mature dendritic cells activate T cells

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41
Q

What is the T cell receptor made up of and how many antigen binding sites does it have?

A

Alpha and beta chain - heterodimer

1

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42
Q

What is the B cell receptor made up of and how many antigen binding sites does it have?

A

2 identical heavy chains
2 identical light chains
2

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43
Q

How quicky does the innate immune response act?

A

Within 96 hours

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44
Q

How quickly does the adaptive immunity response act?

A 
1st exposure (Primary response): 12 days
2nd exposure (Secondary response): 5-7 days
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45
Q

What 3 regions make up the antibody heavy chains and how many different options for each?
Total diff combos for heavy region?

A

Variable - 48
Diversity - 27
Joining - 6
48 x 27 x 6 = 7776

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46
Q

What 2 regions make up the antibody light chains?

Total diff combos for light region?

A

Variable
Joining
340 variants

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47
Q

What is the total no of variants for antibody (heavy + light chain combined)?
Name?

A

7776 x 340 = 2, 643, 840 variants

Combinatorial diversity

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48
Q

What is junctional diversity?

A

Joining of diff regions in antibody chains x precise

Nucleotides added + removed during rearrangement

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49
Q

Where are
a) B cells
b) T cells
developed with gene rearrangement?

A

a) Bone marrow

b) Thymus

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50
Q

What is another name for antibodies?

A

Immunoglobins

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51
Q

What are the 2 types of light chains in antibodies?

A

Kappa/Lamda

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52
Q

What are Fc receptors?

A

Paired constant region segments

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53
Q

What are 4 functions of antibodies?

A

Neutralise toxins + viruses
Opsonise pathogens
Activate complement cascade
Agglutinates particles

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54
Q

What are 3 features IgG?

A

Good at opsonization
Antibody-dependant Cellular Cytotoxicity
4 subclasses of IgG

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55
Q

How is a IgA dimer formed?

A

2 monomers joined by J chain

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56
Q

How do you measure specific IgG?

A

Measurement of antibody titre in serum in response to a vaccine

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57
Q

How many binding sites does a IgA dimer have and what can they do?

A

4
Agglutination + neutralisation
Retention of antigen by adherence to mucus

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58
Q

What is the 1st antibody made in the immune response?

A

Pentameric IgM

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59
Q

How many binding sites does pentameric IgM have and what is this called?

A

10 binding sites

High avidity

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60
Q

What cells have receptors for IgE?

A

Mast cells

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61
Q

What type of antibodies do people with allergies have a higher concentration of?

A

IgE in serum

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62
Q

What cells can improve their specificity for antigens?

A

Only B cells

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63
Q

Where are germinal centres found?

A

Secondary lymphoid tissues contain zones of dividing B cells

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64
Q

What is affinity maturation of B cells?

A

B cells mutate immunoglobulin variable region genes by somatic hypermutation
High affinity variants are selected

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65
Q

What 2 types of cells leave the germinal centre?

A

Memory cells

Plasma cells

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66
Q

What are the 2 locations plasma cells migrate 2 and what antibodies do they produce?

A

Intestines ==> IgA

Bone marrow ==> IgG

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67
Q

What is 1 feature of bone marrow plasma cells?

A

V long lived

Secrete protective antibodies for lifetime

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68
Q

What is a chimeric MA?

A

Mouse MA engineered so variable region of heavy region of heavy + light chains associated mit human contact regions

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69
Q

What is the ending for chimeric MA?

A

-ximab

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70
Q

What is an example of a chimeric MA?

Function?

A

Rituximab
Antibody to CD20 receptor, present in B cells
Targets B cells for killing, remove from circulation + lymphoid tissue
Effective against B cell lymphoma + rheumatoid arthiritis

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71
Q

What is a humanised MA and what is the ending?

A

Prts of variable region that contact antigen are from mouse

-zumab

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72
Q

What is an example of a humanised MA?

Function?

A

Omalizumab
Specific to IgE
Treat moderate-severe asthma

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73
Q

What is the ending of fully human MA?

A

-umab

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74
Q

What is an example of a human MA?

Function?

A

Adalimumab
Specific to TNF alpha
Treat inflammatory diseases

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75
Q

What is plasmapheresis?

A

Plasma separated from blood cell
Replaced mit another solution e.g. saline/albumin
/ treated + returned to body

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76
Q

What bonds holds together the light and heavy chains in antibodies?

A

Disulfide bonds

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77
Q

What is the name of the antigen encoded by MHC genes?

A

Human Leukocyte Antigens (HLA)

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78
Q

What does MHC stand for?

A

Major Histocompatibility Complex

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79
Q

Name 3 features of MHC I

A

Single chain
Associate non-covalently to beta-2 microglobulin
Endogenously expressed on all nucleated cells

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80
Q

Name 2 features of MHC II

A

Alpha-beta heterodimer

Expressed on specialised antigen presenting cells

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81
Q

What type of proteins do
a) MHC I molecules
b) MHC II molecules
present?

A

a) Endogenous proteins

b) Exogenous proteins

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82
Q

Name 5 features of T Cell receptors (TCR)

A 
Heterodimer
2 chains joined by disulphide bridges
2 subtypes alpha-beta, gamma-delta
Consists of variable + constant domains
TCR genes undergo rearrangements from germline before translation
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83
Q

What type of T cells interact with MHC I molecules?

A

CD8+ (Cytotoxic T cells)

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84
Q

What type of T cells interact with MHC II molecules?

A

CD4+ (Helper T cells)

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85
Q

What occurs in signal 1 during T cell response?

A

TCR (T cell receptor) encounter antigen presenting cell bearing MHC receptor

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86
Q

What occurs in signal 2 during T cell response?

A

Co-stimulation

CD28 receptor on T cell binds to CD80/86 on antigen presenting cell (APC)

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87
Q

What are the 4 diff types of cells CD4+ cells can differentiate into and in response to what?

A

Th1 - Viruses + intracellular pathogens
Th2 - Extracellular parasites
Th17 - Extracellular parasites + fungi
Treg- Modulate immune response (Regulatory T cell)

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88
Q

How do Th1 T cells help immune response?

A

IL-2 helps CD8+ T cells to proliferate

IFN-gamma helps macrophages

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89
Q

How do Th2 T cells help immune response?

A

Promote division, affinity maturation of B cells

Promote eosinophils

90
Q

How do Th17 T cells help immune response?

A

Epithelium + fibroblast surfaces - secretion of antimicrobial peptides
Promoting maturation of neutrophils - attract to infection site

91
Q

What are 5 functions of Treg cells?

A 
Suppress:
Stimulatory activity of APC 
Proliferation of responder cells 
Cytokine production of responder cells 
Antibody production from B cells 
Functions of NK + NKT cell
92
Q

What are the precursor cells from the bone marrow that enter the thymus?

A

Thymocytes

93
Q

Where does positive selection for self MHC occur?

A

Thymic cortex

94
Q

Where does negative selection for T cells occur and what cells?

A

Thymic medulla

Thymic Medullary Epithelial Cells (TMECs)

95
Q

What type of antigens do TMECs present?

A

Tissue Restricted Antigens (TRAs)

96
Q

What are 5 peripheral proteins TMECs express and what peripheral tissue are they usually found?

A 
Serum amyloid P - Liver
Trypsin - Pancreas
Insulin - Islets of Langerhans
Crystallin - Eye (Lens)
Thyroglobulin - Thyroid
97
Q

What is Autoimmune Polyglandular Syndrome (APS 1)?

A

Failure of TMECs express TRAs

98
Q

What are 2 peripheral mechanisms of immune intolerance?

A

Anergy

Regulatory T cells

99
Q

What is anergy?

A

Absence of normal immune response to partic antigen/allergen

100
Q

What is anergy important for?

A

Tolerance to:
Antigens x expressed in thymus
Food antigens
Commensal bacteria (living in body)

101
Q

How do Treg cells affect Th cells?

A

X proliferation
X/alter cytokine production
Reduce co-stimulation

102
Q

What are the 2 main types of Treg cells?

A

nTreg

aTreg

103
Q

Where are:
a) nTreg
b) aTreg
produced?

A

a) Thymus

b) Developed from naive T cells in periphery

104
Q

What do nTreg do?

A

Respond to self antigens

Protection autoimmunity

105
Q

What do aTreg do?

A

Constant low level exposure to antigen
Protection autoimmunity
Regulation of responses to food antigens

106
Q

What are PAMPs?

A

Pathogen Associated Molecular Proteins

Conserved products of microbial metabolism

107
Q

What are 3 features of PAMPs?

A

Unique to microbes
Invariant between members of a given class
Vital for microbial fitness

108
Q

How do lymph nodes get swollen?

A

Dendritic cells migrate to nodes + secrete cytokines + chemokines
Upregulation of adhesion molecules on high endothelial venules that line arterioles ==> lymph nodes
Migration of naive T cells ==> nodes
Signal that lets T cells out of nodes is blocked

109
Q

What are the secondary lymphatic organs?

A

Bone marrow, lymph nodes, spleen

110
Q

What are the 2 effects of Tm cells?

A

High frequency

Immediate effector function

111
Q

What are the 2 effects of Bm cells?

A

High frequency

Develop ==> plasma cells

112
Q

What are the 3 features of memory plasma cells?

A

Secrete high affinity
Live for years
Protective immunity

113
Q

What suffix describes inflammation?

A

-itis

114
Q

What is inflammation?

A

Reaction of vascularised living tissue to local injury

115
Q

How are injured tissue be repaired?

A

Regeneration if damaged parenchyma can divide + be replaced

Fibroblastic/glial scar tissue

116
Q

What are the 4 cardinal signs of acute inflammation?

A

Redness
Swelling
Heat
Pain

117
Q

What are the 4 vascular changes in acute inflammation?

A

Transient vasoconstriction of arterioles
Vasodilatation and increased blood flow
Slowing circulation cos of increased permeability of microvasculature
Exudation of fluid + plasma proteins

118
Q

What is acute serous inflammation?

A

Accumulation of fluid can be dominant feature of inflammation e.g. friction blister/burn

119
Q

What is exudate?

A

Inflammatory extravascular fluid

Increased protein content, much cellular debris

120
Q

What is pus?

A

Purulent (thick) exudate rich in leukocytes (mostly neutrophils) + parenchymal cell debris

121
Q

What is the name of the subcellular organelles within endothelial cells?
What do they respond to?
What do they release and what’s contained within them?

A

Weibel-Palade bodies
His + thrombosis factors
Cell adhesion molecules + p selectin

122
Q

When is p selectin released to the stimulation surface?

A

On stimulation with His complement C5a/LPS

123
Q

How does expression of p selectin and e selectin on endothelium affect neutrophils?

A

Neutrophils in blood slow down by interacting with carb receptors + roll along endothelium

124
Q

What is margination?

A

Increased adhesion of inflammatory cells to endothelium + rolling along endothelium

125
Q

What is chemotaxis?

A

Unidirectional migration of cells towards a chemokine

126
Q

What are the 3 main inducers of chemotactic agents for neutrophils?

A

Bacterial production
Component of complement system, partic C5a
Products of lipoxygenase pathway of arachidonic acid metabolism, partic leukotriene B4

127
Q

What is diapedesis?

A

Movement across endothelium

128
Q

What is acute suppurative inflammation?

A

Dominant accumulation of neutrophils, lots of pus

e.g. acute appendicitus

129
Q

What is acute fibrinous inflammation?

A

Inflammation of lung, fibrin + neutrophils

e.g. lobar pneumonia

130
Q

What is acute membranous inflammation?

A

Membrane forms over inflamed tissue

e.g. pseudomembranous colitis

131
Q

What is chronic granulomatous inflammation?

A

Presence of granulomas (macrophages that from spherical mass)
Attracted to chemokines from area of injury

132
Q

What is an early granuloma?

A

Macrophage with a peripheral cuff of lymphocytes

133
Q

What happens to an early granuloma in:

a) Non-infectious causes?
b) Infectious causes?

A

a) Produces non-caseating (non-infectious) epithelial granuloma,
b) Undergo central necrosis
Produce caseating epithelioid granuloma
Fibroblasts produce collagen, turn ==> scar in 8 weeks

134
Q

What is a foreign body granuloma?

A

Giant cells can phagocytose large foreign material

Birefringence on polarised light allows visualisation of foreign material

135
Q

What is immediate hypersensitivity and what is it mediated by?

A

Allergy

IgE, mast cells, Th2 receptors

136
Q

What is atopy?

A

Inherited tendency to make immediate hypersensitivity response
30-50% of pop suffer

137
Q

What is wheal + flare?

A

Raised lesion + surrounding redness

138
Q

How does Th2 cause a direct allergic response?

A

Pollen grains uptaken by APC
Processed + presented as peptides which activates CD4 cells
Produces Th2 response where Th2 cytokines activate B cells
Differentiate ==> plasma cells that make IgE antibodies
Specific to pollen + binds mast cells in nose/skin/mucosal site
Any pollen binding to IgE activates mast cells, degranulates

139
Q

What is immunological self tolerance?

A

Controlled failure to respond to self despite having capability to do so

140
Q

What is autoimmunity?

A

Loss of immunological tolerance to self components

141
Q

What is the spectrum of autoimmune disease?

A

Organ + non-organ specific

142
Q

What is Grave’s disease and what happens in it?

A

Autoimmune thyroid disease
Anti-TSH receptor binds to TSH receptor on thyrocyte
Maintains in ON position + makes unregulated thyroxine
Causes fast heartbeat, hyperactivity, weight loss, bulging eyes, goitre

143
Q

What happens in myasthenia gravis?

A

Antibody AcH receptor + damages them, less available
Insufficient engagement with neuronal stimulus
X/little muscle contraction
Muscular weakness/fatigue

144
Q

How is type 1 diabetes T cell mediated?

A

Supported by:
CD8 T cell mediated killing of B cells
CD4 T cell mediated inflammation
Failure of Treg to suppress

145
Q

What are the 2 types of immunodeficiency?

A

Primary - inherited, rare

Secondary - acquired, common

146
Q

What is an example of primary immunodeficiency?

A

DiGeorge syndrome
Thymus x form so T cells x form
Abnormalities of heart + facial features, immunodeficiencies

147
Q

What is an example of a secondary immunodeficiency and a possible therapy?

A

HIV

HAART - Highly Active Antiretroviral Therapy

148
Q

What 2 cells interact that can cause cancer?

A

Programmed Death -1 (PD-1)
Programmed Death Ligand 1 (PD-L1) on cancer cells blocks PD-1 so cell x die
MA produced can block interaction between 2

149
Q

What is Post transplant lymphoproliferative disease? (PTLD)

A

B cells infected with Epstein-Barr virus
Cytotoxic T cells x control infection
B cells undergo malignant transformation + form B cell lymphoma

150
Q

What 3 characteristics of bacteria are used for classification?

A

Morphological characteristics
Biochemical properties
DNA sequencing of genome

151
Q

What 5 characteristics of viruses are used for classification?

A 
Type of nucleic acid (DNA/RNA)
No of strand of nucleic acid (ss/ds) + physical construction
Polarity of viral genome
Symmetry of nucleocapsid
Lipid envelope
152
Q

What are the 2 types of parasites?

A

Helminths

Protozoa

153
Q

What are helminths?

A

Multicellular worms that infect many organs of body

Commonly GI tract

154
Q

How does transmission of helminths occur?

A

Direct by swallowing larvae/larvae piercing skin

Indirect via intermediate non-human host

155
Q

What are protozoa and what is there life cycle?

A

Single cell organisms
Metabolically active growth stage (trophozoite)
Dorman stage (cyst)

156
Q

How is infection via protozoa acquired?

A

Ingestion of contaminated H2O/food/via insect vectors

157
Q

What are fungi?

A 
Single cell (yeast) with branched filaments (hyphae)
Thick chitin cell wall
158
Q

What stains are used in gram +ve and -ve bact?

A

Primary stain: crystal blue (violet)
Mordant (fixes dyes) - iodine
Decolonizing agent: alcohol/acetone
Counter stain: Safranin (red)

159
Q

Why does gram -ve bact change colour more than gram +ve in staining?

A

Thin peptidoglycan layer

X retain primary staining

160
Q

What are 4 features of a bacterial capsule?

A

Gelatinous layer outside cell wall, composed polysac
Helps bacterial adherence
Antigenic - component of vaccine
Used for identification + lab diagnosis

161
Q

What are 4 features of a bacterial flagella?

A

Organ of motility
Flagellated bact have fixed no + location of flagella
Role of pathogenesis
Used for identification + lab diagnosis

162
Q

What 2 features of pili/fimbriae?

A

Hair-like filaments extend from cell surface

Thinner + shorter than flagella

163
Q

What are the 2 main functions of pili/fimbriae?

A

Attachment (normal ones)

Conjugation (sex pilli)

164
Q

What are 5 features of bacterial plasmids?

A

Additional extrachromosomal genetic material
Mostly circular dsDNA
Capable self replication
Can contain antibiotic resistance genes
Transmissible by conjugation, transduction/transformation

165
Q

What bacteria produce spores?

What special about species?

A

2 species of gram positive
Bacillus - aerobic
Clostridium - anaerobic

166
Q

2 features of bacterial spores?

A

Highly resistant structures formed in response adverse conditions
Contain bacterial DNA surrounded by thick keratin like coat - resistance heat, chem, drying

167
Q

How can you kill spores?

A

Resistant to boiling - killed by autoclaving 15’ at 121 degrees
Only sporicidal solutions kills spores - bleach, other Cl based compounds

168
Q

2 features of viral capsids?

A

Constructed from small no of virally encoded protein subunits - capsomeres
Viral genomes enclosed by capsid protein coat - nucleocapsid

169
Q

3 types of symmetry virus particles show?

A

Icosahedral
Helical
Complex

170
Q

2 features of icosahedral capsids?

A

20 equilateral triangles arranged around face of a sphere

Simplest capsid 3 identical subunits - min is 60 subunits

171
Q

2 features of helical capsids?

A

Genome wind ==> helix

Symmetry only occurs in RNA viruses

172
Q

2 features of complex capsids?

A

Pox viruses e.g. smallpox

Nucleocapsid continuous cylinder surrounded by lipid layer + complex proteinaceous core wall

173
Q

4 features of viral envelope?

A

Lipid bilayer derived from host cell membrane
X present in all viruses
Contain viral glycoproteins (spikes) that project from membrane
Interaction between capsid + envelope mediated by viral matrix protein

174
Q

How is stability virus affected when it’s:

a) Non-enveloped?
b) Enveloped?

A

a) Stable in environ, transmitted by food/H2O

b) Survive transiently outside host + infectious disease persist in environ e.g. HIV

175
Q

What is prion diease?

A

Proteinaceous Infectious Particle
Fatal + infectious neurodegenerative diseases
Misfolded protein alters folding of normal host version of protein

176
Q

3 types of symbiotic associations?

A

Commensalism - 1 organism benefits, other X harm/benefit
Mutualism - benefit to both organisms involved
Parasitism - 1 organism (parasite) benefits at expense of other

177
Q

What are the 2 types of parasites and how do they work?

A

Obligate - intracellular, only reproduce within host cells
Facultative - x rely on host to continue their life cycle
can live + reproduce inside + outside cells

178
Q

3 functions of normal human flora?

A

Helps development of mucosal immunity
Protects host from colonisation mit pathogen microbes
Aids digestion of food

179
Q

What type of flora is easily removed from by routine handwash?

A

Transient flora

180
Q

What is the most common agent in:

a) Resident flora?
b) Transient flora?

A

a) Staph. epidermidis

b) Staph. aures

181
Q

Colonisation defintion?

A

New microorganism grows on superficial body sites without invading body

182
Q

Definition of:

a) Sign?
b) Symptom?
c) Syndrome?

A

a) Objective manifestation of disease, observed + measured by others
b) Subjective features of disease experienced only by patient, infectious can be asymptomatic/symptomatic
c) Groups of symptoms + signs characteristics of a disease

183
Q

4 stages of infectious disease progression?

A

Incubation - time between exposure + onset of specific clinical sign
Prodromal - Period where non-specific symptoms occur
Illness
Recovery (convalescence)

184
Q

What are the 4 types of infections based on occurence?

A

Sporadic - occurs occasionally
Endemic - Continuously present in pop/community/country
Epidemic - Greater no of cases than normal in area within shrt period of time
Pandemic - epidemic disease with worldwide distribution

185
Q

What are the 2 types of infections based on site of infection?

A

Superficial - Replication at epithelium at site of entry
Systemic - Replication at multiple sites, infection at deeper tissues
spread via lymph + blood

186
Q

What are the 2 types of infection based in outcome?

A

Acute - rapid onset of disease, relativ brief period of symptoms, pathogen cleared in few days
Persistent - pathogen x cleared from host, remains in tissue

187
Q

What are the 2 types of persistent infection?

A

Latent - microorganisms persist after initial disease, asymptomatic/symptomatic reactivation
Chronic - Continued production of infectious organism + immune evasion

188
Q

What is nosocomial infection?

A

Any infection acquired in hospital/medical facility

Affects patients + healthcare professionals

189
Q

Why are nosocomial infections common?

A

Easily moved around by staff, patients, visitors

X always prevented by hand washing

190
Q

What molecules on bact bind to host cell receptors?

A

Adhesins

191
Q

Host range defintion?

A

Diff species of hosts a given pathogen can infect

192
Q

Tissue tropism definition?

A

Diff tissues within a given host that are infected by pathogen

193
Q

Permissive cell defintion?

A

Allows pathogen to replicate

194
Q

What enzymes do bacteria produce that allow them to spread to deeper tissues?

A

Collagenase + hyaluronidase - disrupt epithelial basal lamina
Coagulase - triggers formation of fibrin clot around bact, protect from phagocytosis
Leukocidins - degrade WBC
Hemolysins - degrade RBC

195
Q

Pathogenicity definition?

A

Ability of microbe to cause disease

196
Q

Virulence definition?

A

Degree of pathogenicity in a microorganism

197
Q

What are the 3 bacterial virulence factors?

A

Adhesins + invasions
Endotoxins - LPS present cell wall of gram -ve (low toxicity)
Exotoxins - Secreted proteins produced gram +ve/-ve (high toxicity)

198
Q

What are the 4 viral virulence factors?

A

Alter ability of virus to replicate
Modify host defence mechanisms
Enable virus spread in host
Act as toxic proteins

199
Q

What are superantigens (SAgs)?

A

Toxins that stimulate immune system but x require processing to peptides
Bind to MHC-II molecules non-specifically + stimulate large no of T cells
e.g. Toxic Shock Syndrome Toxin 1

200
Q

What is a reservoir (in terms of bact)?

A

Habitat where infectious agent normally grows, lives and multiplies
Usu from source which it’s transmitted to a susceptible host

201
Q

What are zoonotic diseases?

A

Spread between animals and peoples

202
Q

What is an emerging disease?

A

Unrecognized infection/previously unrecognized infection that’s expanded ==> new ecological niche

203
Q

What are the 3 types of contact transmission?

A

Direct contact
Indirect contact - via non living object e.g. eating utensils
Droplet transmission - mucus droplets travel <1 m

204
Q

What are 3 types of vehicle transmission?

A

H2O borne - H20 contaminated by sewage
Airborne - Inhalation of small pathogens + particles
Food borne - due bad sanitation

205
Q

What are 2 types of vector transmission?

A

Mechanical - passive transport of pathogens on vector’s body, flies most common
Biological - pathogen prt of life in vector + transmission to host through bite

206
Q

What is:

a) Horizontal transmission?
b) Vertical transmission?

A

a) Person-person that’s x mother + offspring
b) Transmission mother to child,
Occur in utero across placenta, delivery, breast
feeding

207
Q

What are Koch’s 4 postulates?

A

Microorganisms found in abundance in all suffering organisms but x healthy ones
Microorganism must be isolated from diseased organism + grow in pure culture
Cultured microorganism cause disease when introduced ==> healthy organism
Microorganism reisolated from inoculated, diseased experimental host + identical to orig specific causative agent

208
Q

What are 3 exceptions to Koch’s postulates?

A

Asymptomatic/subclinical infection carriers
Some microbes x grow in vitro
X all organisms exposed to infectious agent will acquire infection

209
Q

What are the 3 types of direct methods of laboratory diagnosis?

A

Cultures of bact/viruses
Microscopy
Detection of nucleic acids

210
Q

How are cultures of bacteria formed?

A

Propagated microorganisms by allowing them to grow in predetermined culture medium under controlled lab conditions

211
Q

What is a colony?

A

Thousands of bact growing on surface that orginate from a single cell

212
Q

4 types of medium bact can be grown in?

A

Defined medium - if exact chem composition known
Enrichment medium - contains component that supports growth of specific types/species bact
Selective medium - designed support growth of specific microorganism
Differential medium - distinguishes closely related microorganism growth on same media

213
Q

How are cultures of viruses formed?

A

Propagation requires cell cultures

Multiplicity of Infection (MOI) refers to no of virions added per cell during infection

214
Q

How is detection of nucleic acids carried out?

A

Detect presence of bacterial + viral DNA/RNA in a patient specimen
Detect organisms slow/difficult to grow in laboratory

215
Q

What is the indirect method of lab diagnosis?

A

Serological tests

Presence of antibodies in serum/microbial antigens in tissue/bodily fluids

216
Q

What is a titre?

A

Antibody conc in sample

No of times can dilute a sample and still detect an antibody

217
Q

How much more antibody must be present in acute sample compared to convalescence sample for a diagnosis to be made?

A

4 fold rise

218
Q

Presence of what type of antibodies indicate an active infection?

A

IgM antibodies

219
Q

What is the difference between:

a) Bactericidal?
b) Bacteriostatic?

A

a) Kill bact

b) Inhibit growth of bact

220
Q

What are the 3 main targets of antiviral agents?

A

Attachment + entry - inhibit fusion of viral envelope/attachment to receptos
Nucleic acid synthesis
Assembly + budding - inhibit viral proteins needed for virion mutation +/ release

221
Q

What are 4 bacterial resistance strategies?

A

Reduce drug ability to penetrate cell
Inactivate drug
Expulsion of drug via general/specific efflux pumps
Modification of drug target site

222
Q

What are 2 viral resistance strategies?

A

Error prone polymerase enzyme in RNA virus means develop resistance mehr than DNA viruses
Mutation within target of antiviral drug

FBS2 (3 decks)

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