MIMM 211 Lecture Notes - Lecture 21: Botulinum Toxin, Virulence Factor, Exotoxin
15 Nov 2016
School
Department
Course
Professor
Document Summary
2 examples of bac pathogens, extra vs intra, but notice similarities: enterohemorrhagic e. coli: (ehec) extracellular diarrheal, salmonella typhimurium: intracellular diarrheal. To define a bacterial virulence factor (bvf): (cid:373)olecular versio(cid:374) of koch"s postulates, by falkow. Gene encoding the factor present in strains of bac that cause disease, not in avirulent strains. Can ko gene to reduce virulence, rescue restores virulence. Expressed during infection, specific immune response to gene protects against it. E. coli can be harmless, then acquire bvfs via plasmids, phage, pai, tn. Can be transferred via horizontal gene transfer, between cells! Examples of bvfs: adhesins: help with sticking into host environment, nutrient acquisition systems, fe++ is (cid:374)eeded fo(cid:396) (cid:271)a(cid:272)te(cid:396)ial g(cid:396)o(cid:449)th too. Siderophores are assoc. with pathogens: capsule, outside the cell wall, usually slimy, usually made from polysaccharide, protect bac from phagocytosis, ex. Streptococcus pneumoniae kills mice only if it has capsule bvf: toxins: exo, endo toxins, exotoxins.
