7. Listeria

Most human listeria infections are caused by

L. moncytogenes

Invasive listeria infections in pregnant women

usually leads to miscarriage, stillbirth, premature delivery, or life-threatening infection of the newborn.

Listeria in the refrigerator

can still grow slowly at that temp

How does listeria know when it is inside the host

uses the Hpt G-6-P transporter as a signal

When Hpt transports G-6-P, what happens

transcriptional regulator PrfA is released from the membrane and activates expression of Listeria virulence factors

PrfA

trascriptional regulator that activates listeria virulence factors required for human host survival

Listeria adhesion and entry

mediated by internalins InlA and InlB

internalins InlA and InlB

bind host proteins leading to uptake nd internalization of listeria in phagosome

How does listeria escape from the phagosome

listeriolysin O (LLO) and phospholipases PlcA and PlcB are activated to release listeria from phagosome into the cytoplasm

How are LLO and PlcA and PlcB activated

by the drop in pH in the phagosome

Listeriolysin O (LLO)

pore forming toxin

Phospholipases PlcA and PlcB

break down host phospholipids

How does LIsteria spread from cell to cell once escaped from the phagosome into the cytoplasm

they can move around and between cells using their actin tails

Actin polymerization for cell-cell spread

mediated by ActA to recruit host cell actin polymerization machinery.

Cell-cell spread via ActA leads to

listeria being enveloped by a double membrane, then having to escape again using LLO PlcA and PlcB to continue infection

Which barriers can be crossed by Listeria

GI epithelial barrier
BBB
Placental barrier

How does Listeria cross the epithelial barrier

Using M cells, goblet cells, or epithelial cells

How does listeria cross the placental barrier

using adhesins, InlA, InlB

Which method is used by listeria to cross the BBB

all 3, transcellular, paracellular, and trojan horse