Infection 2 Flashcards
What is important in initial EPEC attachment to the epithelial cells?
Type IV pili
Why are type IV pili important in initial EPEC attachment?
They interact with N-acetyl-lactosamine-containing receptor proteins on the host cells
What do type IV pili do after coming into contact the host cell?
Retract to pull EPEC into close contact
Why does EPEC need to be in close contact with the host cell?
So it can puncture the host cells membrane and inject effector proteins in using the type 3 secretion system
What is Tir?
Translocated intimin receptor
What does Tir do?
Injected into host cells by EPEC, localises to host cell membrane and provides receptor for Intimin
What is intimin?
Outer membrane protein made by EPEC strains
How do Tir and Intimin interact?
Tir is on the host cell and provides a site to where intimin can bind, thus attaching EPEC to the host cell
Benefit of putting EPEC onto a pedestal?
Puts it away from the host cells surface so it won’t be taken up and engulfed by the host
Example of a disease that is caused by biofilm formation?
Cystic fibrosis–> biofilm in lungs
How may bacteria go deeper into an organism, past epithelial tissues?
Enter host cells directly and pass through
Move between host cells
Remain within the host cells
Which organisms are obligate intracellular parasites?
All viruses
Two ways that bacteria can enter host cells?
Zipper and trigger mechanisms
What do both zipper and trigger mechanisms involve?
Hijacking or subversion of host cell machinery and functions
What does zipper mechanisms involve?
Intimate contact between bacteria and host cell membranes
Engagement of host cell receptors initiate entry
What does trigger mechanisms involve?
Intimate contact between bacteria and host cell membranes
Usually involves delivery of bacterial effectors (toxins) into host cell to trigger host cell cytoskeleton rearrangement that engulfs bacterium
How does zipper entry work?
Exploiting receptors on the host cell surface to remodel the cells cytoskeleton and influence uptake
Eventually the bacteria is taken up
Remodelling is done by protein on the bacterial cell surface
How does trigger entry work?
Inject proteins called effectors into host cells
Effectors then trigger host cytoskeleton reorganisation
