Salmonella Cheat Sheet

University:
The University Of Western Ontario
Course:
Pathology 3500B | Human Pathology
Academic year:

2023
Views:

141

Pages:

2
Author:

Kyuwon J.

Salmonella ● Chromosome structure ○ Circular chromosome about 4.8 Mbp ○ Pathogenicity Islands (SPI) ■ SPI 1 = invasion of epithelial cells ● T3SS-1 apparatus ■ SPI 2 = intracellular survival +macrophage modulation ● T3SS-2 apparatus ■ SPI 3-SPI 6 = magnesium transport + fimbrial adhesion +antimicrobial resistance ● Horizontal gene transfer ○ Virulence test though phage integration + plasmid ○ Phage encoded gene helps immune evasion + toxin production ○ Salmonella virulence plasmid will encode spvB ■ Destabilize host actin cytoskeleton Factor Reservoirs Poultry, reptiles, cattle, humans (esp. chronic carriers) Geographic burden Typhoid: South Asia, Africa; NTS bacteremia: Sub-Saharan Africa Zoonotic potential High — especially in S. Typhimurium and S. Enteritidis Infective dose Very low for S. Typhi (~10²–10³ CFU); higher for NTS Transmission route Fecal–oral, direct animal contact, vertical transmission in eggs ● Membrane remodeling by SCV ○ SCV selectively recruits RAB GTPase ■ Rab 5, 7,11 are trafficked away from lysosomal fusion ○ SCV avoids lysosomal associated hydrolases ● Actin Cytoskeleton Subversions ○ SPI-1 ■ SopE mimics host GEF = will activate Rac1/Cdc42 = ruffling ■ SptP reverses actin ● Stabilize host cell after invasion ● Immunity Evasion ○ Competes for limited magnesium and iron in host environment ■ MgtC/MgtB (Mg2+ transporter) ■ SitABCD ,IroN, FepA (Fe3+ collectors) Host cell Manipulation ○ Dendritic cell Hijacking ■ Enters DC ● Use actin tail to move in lymph nodes ■ Apoptosis is avoided using downregulation of caspase - 3 ○ Epithelial Cell reprogram ■ Proinflammatory cytokines ● Recursion of Neutrophils ■ Intestinal inflammation ● Suppresses commensal flora ● Allows salmonella to monopolize through nitrate respiration Lab Vivo Model ● Mouse typhoid ○ S. TYphimurium mimicking S typhi in mouse ○ Typhoid like systemic disease ● STAMPS ○ Gene fitness tracking Vitro ● Gentamicin Protection assay ○ Intracellular survival ● Organoid model ○ Stimulation of human gut epithelium ○ Used for studying invasion of pathogenic molecule/organisms ● CRISPR screening ○ Identification host gene ○ Can isolate genes used for Salmonella replication ■ Gene used for regulating autophagy +endosomal sorting