Lecture 11: Virulence Factors

Question 1

What is a bacterial virulence factor

Answer 1

A product or strategy that contributes to the ability of the bacterium to survive in the host and or cause infection

Question 2

What do virulence factors do

Answer 2

localize, adhere, compete for resources, overcome host defenses

Question 3

How does N. meningitidis enter the CSF?

Answer 3

Causes tight junction disruption to induce a break in the blood-brain barrier.

Question 4

How do H. pylori penetrate the stomach lining

Answer 4

Uses flagella to penetrate the stomach lining, pH closer to normal. Burrows into mucus lining, to get towards epithelial cells. Cannot persist in the stomach without the flagella. needs the more neutral pH of the epithelial cells.

Question 5

How do bacteria stick to the surface?

Answer 5

Fimbriae: a smaller version of pilus, Gram +, and Gram -
important for biofilm formation
All bind to receptors

Afrimbral adhesins: adhesions that are not fimbriae.
FrimH in E.coli

Question 6

Bacteria can create ___ Films to allow for adherence, even under the sheer force of the flow.

Answer 6

Biofilms produced from secreted sticky “polysaccharides”

Question 7

what are siderophores

Answer 7

Small molecules that bind to iron-bound host proteins. Steals the iron from host proteins. Iron acquisition is very important. Some bacteria can take iron straight from hemoglobin.

Question 8

How can bacteria overcome host defenses?
such as:
skin/mucus layer

Answer 8

Glycosylhrolases - degrades the glycan-coated mucin. Mucin is coated in glycans- sticky

Proteases - degrade proteins. Cleavage of the core protein to rid the mucus. Bacteria can be stuck to the bacteria (host defence)

Question 9

How can bacteria overcome host defenses?
such as:
CAMPs - cationic AMPs

Answer 9

Host CAMPS bind to negatively charged membrane components. Destabilize the membrane.

Bacteria can modify membrane (-) charged components. Attached + charged AA to the components.

bacteria can secrete negatively charged capsules to squelch out the CAMPs

Increases hydrophobicity of membrane. CAMPs can not penetrate the membrane

Question 10

Bacteria have a protease for what Immunoglobulin

Answer 10

IgA protease to cleave IgA and the mucosal immune response