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MCB C103 > Final > Flashcards

Final Flashcards

1
Q

Salmonella Cell Biology

A

Gram -
Rod-like
Motile

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2
Q

Salmonella diseases

A

Gasteroenteritis (typhimurium)
Typhoid fever (typhi)
Arthritis (Reiter’s syndrome)

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3
Q

(S) SPI1

A
  • Encodes T3SS ex. SopE
  • Important for invasion of intestinal epi cells
  • induces strong inflamm response via NAIP/NLRC inflammasome
  • injects bacterial effector into host cytosol to initiate trigger mechanism via actin poly
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4
Q

(S) SPI2

A
  • Encodes T3SS ex. SifA
  • Invasion of macrophages
  • Important for intracellular growth
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5
Q

(S) SopE

A
  • mediates nt activation and exchange of Rho (GEF)
  • short half life
  • induces membrane ruffling
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6
Q

(S) SipA

A
  • binds directly to actin
  • decreases [critical] for poly
  • inhibits depoly
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7
Q

(S) SptP

A
  • blocks actin poly
  • longer half-life than SopE
  • reverses effects of SopE
  • SopE+SptP=no ruffling
  • SopE alone = no ruffling
  • SptP alone = loss of F-actin
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8
Q

(S) SifA

A
  • virulence
  • Sif formation
  • SifA reside in vacuole
  • SifA- released into cyto
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9
Q

(S) Sif

A

Salmonella induced filament

  • allows creation of own niche in vacuole
  • SPI2- fail to induce Sifs
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10
Q

(S) PhoP

A
  • Two component regulatory system to control virulence
  • regs LPS modifications
  • changes expr >200 genes
  • antimicrobial peptide resistance
  • SPI2 activation
  • PhoP- does not immunize
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11
Q

(S) Prgs

A

PhoP repressed genes

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12
Q

(S) Pags

A

PhoP activated genes

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13
Q

(S) PhoQ

A
  • two component reg system to control virulence

- bacterial PRR such that AMPs =PAMPs

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14
Q

(S) PhoPc

A
  • constitutively active = locked in active configuration
  • no Prgs expr, only Pag
  • virulence same as PhoP-
  • PhoPc immunizes mice
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15
Q

(S) Salmonella typhi vaccine

A
  • Salmonella LPS has galactose
  • vaccine is gal auxotroph
  • bac are grown w gal, WT LPS syn
  • in vivo, no gal, only rough LPS syn
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16
Q

(S) Typhoid toxin - makeup

A
  • 1 subunit homology CDT
  • 2 subunits homology PT
  • CDT= DNAse –>apop
  • PT, PltA=pertussis-like toxin A –>ribosylation
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17
Q

(S) Typhoid toxin - mechanism

A

-induces cell arrest in G0-G1 phase

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18
Q

(S) Typhoid toxin - secretion

A
  • made by bac growing in SCV
  • assembled in periplasm
  • secreted into lumen of SCV with help of TtsA
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19
Q

(S) Typhoid toxin - export

A
  • vesicle-carrier intermediates

- cannot intoxicate cell in which it is produced bc Ab to toxin protects cell

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20
Q

(S) Rab29 and Rab31

A
  • GTPases

- required for typhoid toxin export

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21
Q

(S) Rab32

A
  • GTPase
  • prevents S. typhi from growing in non-human macrophages
  • mediates anti-bac defense mechanism
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22
Q

(S) GtgE

A
  • T3SS in S. typhimurium
  • protease that cleaves Rab32 (with SopD as GAP) and prevents recruitment to vacuole
  • expr of GtgE allows S. typhi to grow in macrophages
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23
Q

(S) Nramp

A
  • manganese transporter
  • makes 129 mice resistant to S. typhimurium
  • starves bac of Mn2+ needed to grow
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24
Q

(S) Aerobic vs fermentation

A
  • 129 can transmit (supershedder) bc wins competition in gut w microbiota
  • ttr gene cluster allows use of tetrathionate as e- acceptor
  • tetrathionate req Cybb
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25
Q

(S) Cybb

A
  • phagocyte oxidase
  • makes tetrathionate for respiration
  • produced by neutrophils that swarm gut during infection
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26
Q

(S) NAIP/NLRC4

A
  • inflammasome
  • activated by SPI1 inj of flagellin, needle and rod components
  • caspase 1 cleaves pro-IL1 = IL1 –> neutrophil recruitment
27
Q

(S) Outcompete microbiota

A

Salmonella➔SPI-1➔flagellin, rod, needle➔NAIP/NLRC4➔Caspase-1➔IL-1➔ neutrophil recruitment to gut➔inflammation➔ conversion of thiosulfate to tetrathionate➔ consumption of tetrathionate by ttr+ Salmonella➔ replication of Salmonella to high numbers in the gut➔ lots of bacteria shed in feces➔ transmission

28
Q

(LP) Cell Biology

A
  • gram -
  • motile
  • functionally obligate, but not technically
29
Q

(LP) Disease

A
  • replicates in alveolar macrophages
  • inflammatory pneumonia
  • no human –> human transmission
  • high LD50
30
Q

(LP) Dot/lcm T4SS

A
  • Dot= defective for organelle transport
  • Icm= intracellular multiplication
  • main virulence factor
  • used to inject effectors which create LCV
  • targets host processes (generalist)
  • T4SS = T3SS but can secrete nucleic acids
31
Q

(LP) LCV

A
  • legionella containing vacuole
  • has ribosomes on surface
  • takes 4h to form
32
Q

(LP) effectors

A
  • more than any other bac
  • functional redundancies
  • generalist ie provides diversity
33
Q

(LP) B6 macrophages

A
  • LP cannot replicate
  • pyroptosis
  • NAIP5 uses caspase-1 to cleave and activate pore-forming gasdermin D
34
Q

(LM) Cell Biology

A
  • cytosolic
  • gram +
  • Low G+C
  • grows rapidly
  • saprophyte
  • food-borne pathogen
35
Q

(LM) Disease

A
  • infects adherent cells and macrophages

- pregnant women and immunocompromised

36
Q

(LM) Life cycle

A
  • phagocytosis
  • phagosome rupture
  • bac surrounded by actin cloud/tail
  • propelled from cell into listeriopod which is engulfed by neighbouring cells
37
Q

(LM) LLO

A
  • CDC family
  • essential for pathogenicity
  • encoded by hly gene
  • allows escape from phagosome
38
Q

(LM) PEST

A
  • targets proteins for degradation in cyto so they don’t lyse PM
  • inactivation by phosphorylation or ubiquitinylation which targets for degradation by proteosome
39
Q

(LM) prfA

A
  • tx factor for operator binding of operon
  • plasmids 10x less virulent bc 30 copies of plasmid incr # binding sites and sequester prfA so other virulence factors are not tx
  • contains ActA, actin motility
40
Q

(LM) Murine model

A
  • mice immunized w LM resistant to LM, S and BCG 1-2 weeks later
  • after 1 month, only resistant to LM
  • non-specific immunity from macrophage activation
  • specific immunity from CD8/4 T cells
  • Ab plays no role
41
Q

(LM) Reason for potent immunity

A
  • entry and growth w/in AG presenting cells
  • MHC class 1 pathway
  • induction of innate immunity that promotes CMI
  • lack of cell death
  • lack of suppressive cytokines that block CMI
42
Q

(LM) IFN-beta

A
  • primary host gene induced

- STING activation necessary

43
Q

(LM) MDR

A
  • multidrug resistance transporters
  • play role in active efflux of antibiotics and toxic compounds
  • repressed by TetR (tetracycline repressor)
  • export c-di-AMP that activates STING and produces IFNB
44
Q

(LM) c-di-AMP

A
  • activates STING–> IFNB

- when injected into tumor, induces tumor-specific CD8 that eliminate tumor

45
Q

(LM) Vaccine vector

A
  • highly manipulatable
  • infects Ag presenting cells w/o killing
  • potent inducer of CD8
  • attenuated mutants (ActA-) retain immunogenicity and can be safely administered
  • not neutralized by vector-specific immunity
46
Q

(LM) actin based motility

A
  • Actin poly essential
  • inhib by cytochalasin D
  • ActA req for motility
47
Q

(LM) ActA

A
  • In PrfA regulon
  • has sec signal and TM domain (polar localization)
  • activates Arp2/3 at bac surface by imitating WASP
48
Q

(LM) Cofilin and capping prot

A

Cofilin = depolymerizing

Capping prot = limits actin assembly to new filaments

49
Q

(T) Cell Biology

A

-gram variable (+)
-non-motile
-thick, waxy coat
-mycolic acid and lipids
- thicker than normal g+
-acid-fast stain sp for
mycobac

50
Q

(T) Disease

A
  • infection via aerosol
  • replication primarily in lungs
  • bloody cough, weight loss, nausea, fever
51
Q

(T) Antibiotics

A
  • Isoniazid (INH)

- Rifampin (RIF)

52
Q

(T) Antibiotic resistance

A
  • MDR TB (multiple drug resistant)
    • resistant to INH and RIF
    • curable w 2 yrs treatment
  • XDR TB
    • extensively resistant
    • often not curable
53
Q

(T) ESX-1

A
  • T7SS
  • disrupts/punctures phagosomal membrane
  • req for intracellular replication and virulence
  • arrests phagosome maturation
    • provokes IFN response
54
Q

(T) BCG

A
  • attenuated mycobacterium
  • given to children to protect against TB meningitis (not pulmonary)
  • lacks ESX-1
  • cures bladder cancer b/c incr in TNF
55
Q

(T) Infection

A
  • 1st 3wks unchecked
    • CD4 and IFNG critical
  • latent phase
    • granulomas, stable standoff
    • bac replication is balanced
  • active phase
    • extensive bac replication
    • high inflamm & tissue destruction
56
Q

(T) Granuloma

A
  • method for body to contain bac it can’t eliminate
  • good sites for bac replication
  • dead cells in center provide food for replication
57
Q

(T) Central paradox

A
  • The immune response is required to control bacterial replication (immunodeficiency in CD4 T cells or IFNɣ results in susceptibility to MTB)
  • Immunopathology ultimately causes lung destruction and death (and enhances bacterial replication and transmission)
58
Q

(T) IFN-G

A
  • Important host factor to control MTB replication
  • Induces Autophagy, Antimicrobial peptides, Nitric oxide
  • Humans deficient for IL-12 or IFN-G signaling are highly susceptible for mycobacterial infection
  • HIV induces decreases in DC4 count correlate with susceptibility to TB
  • Majority antigen-specific T cells isolated from a TB patient produce IFN-G upon stimulation
59
Q

(T) iNOS

A
  • inducible nitric oxide synthase
  • induced by IFN-G
  • mediates resistance to MTB
60
Q

(T) TNF-a

A
  • Treated with anti-TNF-a causes 4-5x more incident of TB

- Also causes a greater risk of disseminated and extrapulmonary disease

61
Q

(T) CD8 Tcells

A

-CD8 T cell knockout causes a greater increase in TB infection

62
Q

(T) IL-1

A
  • IL-1 deficiency causes increased susceptibility to TB

- No clear answer as to what IL-1 does to protect against TB

63
Q

(T) Type I IFN

A
  • Increased levels causes susceptibility to TB
  • controls viral infections by inducing an anti-viral state to block viral replication
  • confuses the immune system by inducing an anti-viral state rather than anti-bacterial immune response and increases susceptibility to TB
  • HDT therapy inhibits type I IFN and promotes TB resistance (Expensive to administer)
  • TB induces Type I IFN via activation of cGAS STING pathway
64
Q

(T) Diagnosis

A
  • Active TB
    • X-ray
    • Smear test
      • Specific but not sensitive test that gives a rapid and inexpensive answer
    • Culture test
      • Tb grown in media. Slower and more difficult than smear (but more sensitive)
  • Latent TB
    • Tuberculin skin test
      • Cannot be tested in individuals vaccinated with the BCG vaccine
      • PDD is injected into the skin (purpified protein derivative)
      • Bump forms on skin due to immune response
      • Large bumps means infected with TB
    • IFN-G release assay
      - IGRA detects interferon gamma produced by T cells in response to MTB
      • Does not give false positives

MCB C103 (3 decks)

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