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Infection And Immunity > Unit 1: Core Concepts In Pathogen Biology And Immunology > Flashcards

Unit 1: Core Concepts In Pathogen Biology And Immunology Flashcards

1
Q

What are the 7 Baltimore classifications?

A

1) dsDNA
2) ssDNA
3)dsRNA
4)ssRNA (+ve)
5)ssRNA (-ve)
6)ssRNA +ve RT
7)dsDNA RT

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2
Q

What is the general sequence of events for virus replication?

A

Attachment (spike proteins) - entry - uncoating - gene expression - replication - assembly - release
(DNA pretends to be chromosome, RNA pretends to be mRNA)

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3
Q

What is the difference between positive and negative sense RNA?

A

-ve sense like dsRNA requires use of RNA dependant RNA polymerase (RdRp)
Positive can be read by ribosomes
Negative is the copy of the positive
Chemically the same, different coding ability

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4
Q

Why do viruses gain entry to cells via endocytosis?

A

Entry without killing the cell - eg can present as a ligand to a receptor without alerting immune responses

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5
Q

What class of virus integrate into the host genome?

A

Retroviruses

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6
Q

All RNA viruses require what as an intermediate?

A

dsRNA intermediate - except retroviruses

Plus strand translated directly, complementary copy transcribed to messenger senses before translation (neg sense)

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7
Q

Enzymes that copy nucleic acid work in what direction?

A

5’ to 3’

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8
Q

Why do cells take up virus particles?

A

Endocytosis normal process (activated receptors internalises), maturation + fusion with lysosomes

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9
Q

What examples of viruses have a lipid bilayer and what is present here?

A

Virally encoded proteins
Hepatitis C, influenza A…
Rabies has matrix protein

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10
Q

what is the function of virus particles?

A
  • protect viral nucleic acid from degradation
  • machinery to deliver n.acid to uninfected cell
  • transport from one host to another
    transport from one cell to another
  • factor for determining virus tropism
  • some protect n.acid from degradation inside cell; machine for efficient replication
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11
Q

what processes occur in order to drive virus binding to host cell surface receptors?

A

decrease in pH = conformation shift in r.binding protein = fusion to v.membrane to surface membrane
first c.change to embed into host membrane, second c.change brings 2 membranes = pore formation and membrane fusion

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12
Q

give some examples of fusion triggers and an example virus/ fusion protein

A

receptor binding - HIV (gp41)
low pH - Influenza A (HA)

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13
Q

how do non-enveloped viruses enter cells?

A

nucleic acid ‘injected’ into cell: attachment - conformational shift = pore through cell membrane - translocation across membrane into cell - replication
OR
attachment - endocytosis - acidification = fusion proteins make membrane pore - nucleocapsid core released in cytoplasm - transcription

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14
Q

features of Baltimore group 1 viruses

A

-large genome
-nucleus replication
-replicates as an episome
-herpesvirus, chichenpox
-poxvirus replicates solely in cytoplasm

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15
Q

features of Baltimore group 2 viruses

A

-smaller genome
-dsDNA intermediate circle mechanism
nonenveloped
-in rapidly dividing cells
-parvovirus

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16
Q

features of Baltimore group 3 viruses

A

-genome 10-12 segments of dsRNA
-replicate in cytoplasm
-icosahedral capsid doesn’t completely disassemble during cell entry
-bluetongue virus

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17
Q

features of Baltimore group 4 viruses

A

-most common type
-messenger sense RNA genome
-replication in cytoplasm
-Polio, FMDV, Flavivirus

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18
Q

features of Baltimore group 5 viruses

A

-in complex with RdRp
-nucleus replication
-influenza A, Ebola

19
Q

features of Baltimore group 6 viruses

A

-v.RNA copied to DNA (reverse transcriptase) transported to nucleus - integration into host DNA
-integrated v.RNA includes promoter = transcription
-retrovirus genome = gag (nucleocapsid), pol (r.transcriptase) + env (envelope proteins)
HIV

20
Q

features of Baltimore group 7 viruses

A

-mature virion = gapped DNA
-when in nucleus, genome covalently closed + transcribed
-reverse transcription in nucleocapsid
-uncommon
-RNA inermediate
Hep B

21
Q

What colour are Gram +ve and -ve stains?

A

+ve = purple (eg staphylococcus)
-ve = pink (eg salmonella)

22
Q

what are the different components of the gram+ve bacterial cell wall?

A
  1. WTA
  2. LTA
  3. peptidoglycan
  4. cell membrane
  5. cytoplasm
23
Q

what are the different components of the gram-ve bacterial cell wall?

A
  1. LPS
  2. Lipid A
  3. outer membrane
  4. peptidoglycan
  5. periplasm
  6. cell membrane
  7. cytoplasm
24
Q

what are some features of the G-ve outer membrane protein?

A
  • permeable to peptides etc with low molecular weight (<700Da)
  • allows passage of hydrophilic molecules only
25
Q

what us the function of the O-antigen repeat in LPS?

A

immunogenicity - is very variable and can look like host protein (with addition of eg sialic acid) = immune evasion
core oligo = stability

26
Q

what is the function of Lipid A in LPS?

A

is endotoxin A - toxicity and innate immune signalling

27
Q

what does the appearance of a spore coat in bacteria allow for?

A
  • increased transmission - are completely resistant to environmental stresses = preservation = transmission
  • interfere with infection control
28
Q

what is the term for which bacteria communicate with one another?

A

Quorum sensing = can caused coordinated specific gene expression etc

29
Q

name some examples of bacteria that form biofilms and their effects in infection and immunuty

A
  • Legionnaires disease (legionella pneumophilia) - grows in AC units
  • E.Coli - in catheters
  • Staphylococcus aureus - heart valves
  • are all resistant to clearance via antibiotics
30
Q

what are the components of the innate immune system?

A
  • physical barriers
  • phagocytes and inflammation
  • NK cells
  • pattern recognition molecules
  • cytokines
31
Q

what is the function of NK cells?

A
  • type 1 a/B-interferon released/expressed during expression
  • healthy cells = inhibiting molecules
  • NK cell circulating, induce cell death to expressing cells
32
Q

describe the process of phagocytosis

A
  • attachment phase
  • phagosome formation
  • phagolysosome = killing + digestion
  • postdigestion phase
33
Q

what is a cytokine?

A

protein molecules secreted by cells that regulate the function of the cell/ other cells
= complex interaction between cells of the immune system

34
Q

what is a chemokine?

A

structurally homologous molecules with ability to bind G protein-coupled receptors
- stimulate leukocyte movement = regulation of cell migration

35
Q

what is the role of chemokines?

A
  • widespread alert of infection
  • characteristic change of endothelial cells = ‘sticky’
36
Q

what is the role of complement?

A
  • produced at liver
  • proenzymes
  • activate antigen-complement or microbe direct = microbe destruction
  • broken down microbe = white cell recruitment + communication
37
Q

acute inflammation characteristically involves what type of white blood cell?

A

an influx of neutrophils

38
Q

what is the difference between T and B cell pathogen recognition?

A

B cell = native protein recognition
T cell = degraded protein bound by MHC

39
Q

what MHC molecules do CD8 and CD4 T cells recognise?

A
  • CD8 = MHCI
  • CD4 = MHCII (expressed by APCs eg B cell)
40
Q

what are the 5 classes of antibodies and how are they defined?

A
  • defined by constant region
    1. IgM
    2. IgD
    3. IgG
    4. IgE
    5. IgA
41
Q

what antibody class is associated with allergies?

A

IgE

42
Q

what antibody class is found at highest concentrations in serum?

A

IgG

43
Q

where are T cells produced?

A

in the thymus

44
Q

what term describes the making of all blood cells?

A

heamatopoiesis

Infection And Immunity (8 decks)

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