Virulence Factor Examples

Mutation of DNA of protozoan Giardia result in loss of adhesion disk

Protozoan less virulent, because loss attachment mechanism

viral DNA mutation produces new ligand that bind nerve cells

virus more virulent = helps attach to cells

Mutation of bacterial DNA results in bacteria no longer able to produce hyaluronidase.

bacteria less virulent - no longer able to penetrate btwn cells; can enter thru cuts & scrapes

Normal intestinal bacteria acquires ability to make enterotoxin by exchanging DNA w/ diff species

bacteria more virulent because make harmful changes via toxin damaging intestinal tract

bacteria that is normally harmless because of rapid phagocytization acquires a capsule via DNA exchange

bacteria more virulent by helping avoid immune system in capsule