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Unformatted text preview: 20.106J Systems Microbiology Lecture 20 Prof. Schauer Toxins and diagnostic microbiology Brock 21.10-21.12 and Chapter 24 Toxin o The latin root applies to a bow (like a bow and arrow) the idea is that it kills like an arrow o Endotoxin lipopolysaccharide o Exotoxins Proteins Mostly enzymes Three broad types: Cytolysins A-B toxins Superantigens Cytolysins o Example: streptococcus pyrogenes This is what gives you strep throat Hemolysin produces a toxin that lyses the cells around it You can see this happening to cells if you plate this bacteria on agar This used to be used to diagnose strep throat, before a quicker test was developed Why does this toxin exist? It doesnt lyse red blood cells in your blood stream. Its there to fight the neutrophils that your body sends to kill the streptococcus If you stay sick with strep throat for very long, it can cause an autoimmune disorder where your own immune system attacks and damages the endothelial lining of your heart valve A-B Toxin o Example: Corynebacterium diptheriae Diptheria used to be a major public health concern Antitoxin you develop a toxoid (antigenic, but not toxic) If you immunize people with this toxoid, you develop an antitoxin (antibody that will neutralize the toxin) Emil Adolf von Behring In Boston theres a statue of the husky dog that brought the precious load of antitoxin on a sled across Alaska when there was a big outbreak of diphtheria...
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- Spring '06