lecture20

lecture20 - 20.106J – Systems Microbiology Lecture 20...

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Unformatted text preview: 20.106J – Systems Microbiology Lecture 20 Prof. Schauer ¾ Toxins and diagnostic microbiology ¾ 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 doesn’t lyse red blood cells in your blood stream. It’s 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 there’s 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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lecture20 - 20.106J – Systems Microbiology Lecture 20...

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