Intracellular pathogens

Question 1

Bacteria invasion of host cells

Answer 1

1. The bacteria releases toxins into the host cell that promote phagocytosis.
2. The bacteria becomes trapped in a phagosome, which is sent to be fused with a lysosome for degradation.

Fate 1: The bacteria simply survive the lysosome.
Fate 2: the bacteria secretes effectors that prevents fusing, living in the vacuole.
Fate 3: the bacteria escapes the phagosome, moving around in the cell using actin based motility.

Question 2

Avoiding host cell destruction

Answer 2

They produce proteins that mimic cytokines. They secrete host manipulating effectors via T3SS. They downregulate cytokine production. They can inhibit apoptosis and necrosis. they can alter antigen presentation.

Question 3

Shigella

Answer 3

They use the T3SS to secrete many effectors. They produce VirG which recruits N-WASP proteins that activate Arp2/3 which nucleates actin tail formation. VirA is produced to destroy microtubules, clearing the bacterias path. IscB prevents VirG from triggering immunity.