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Report on Science Café – October 2009
by Jeff Pugh
Science Cafe of Tuesday, Oct. 27th concerned bacteria – an excellent topic considering the current controversy over vaccinations. I especially liked Dr. DeVinney’s introduction: Bad To The Bone – The 1% of Bacteria that are Pathogenic. She compared bacteria to bikers, where only 1% cause all the trouble, but those are the ones we know of the best.
Some bacteria, like botulism, are not dangerous in themselves, but produce a toxin that is. From food poisoning from non-acidic home canning to smoothing the wrinkles in your face is quite a journey for one bug! I didn’t realize that another famous bug, E. coli, is terrific for you in your digestive tract, but is deadly for kidney failure when prowling out on its own, or in your water source, as it did in Ontario a few years ago.
Bacteria reproduce asexually, so that ought to give them identical DNA for generations, but their ability to adapt is phenomenal. Microbiologists use E. coli for genetic engineering, knocking out the harmful parts of their genome, to use the bacterium as a delivery tool for antigens.
Recent microscopy advances, such as real-time 3D observations, have allowed great insight to the lives and loves of the lowly bacteria. Shigella and salmonella force their way into the gastro-intestinal epithelial cells, and while there, remodel those cells to ‘hide’ from the immune system. Lysosomes in the cell are acid baths meant to destroy microphages, but E. coli can turn them into romantic hot tubs and reproduce like Californians. Other bacteria can inject a microscopic syringe into white blood cells, paralyzing them, so they can no longer attack the phagocytes, and take them over.
So microbiologists ask if that feature can be turned for the good, reforming their purpose – disarming other bacteria, or as a cancer therapy and vaccine delivery system?
Dr. Schryvers discussed vaccines and antigen engineering. Apparently, most vaccines are very simple in design, and are ‘obsolete’ for combating the newer forms of virus. He is trying to develop the ‘Windows 7′ version of vaccine, as the DOS version is having virus trouble of its own. The new version would contain a new antigen for much better vaccine coverage. Bacteria can use the iron-based proteins in humans to create decoys to avoid an immune system response, and in doing so, these previously benign bacteria can become pathogens. Bacteria can change their ’surfaces’ so as to be unrecognizable to our defenses. Sneaky buggers. The abrupt changes in bacteria are a mystery – we don’t know what triggers these mutations, or why some bacteria try to kill their host – an evolutionarily foolish thing to do. Further, most bacteria are species-specific, and rarely ‘jump’ hosts to another species. Interestingly, many diseases are symptomatic – a result of the body’s over reactive immune system causing the disease, not the bacteria. The Spanish Flu of 1918-1919 killed 100 million people, mainly the young, fit, and healthy, as their own good immune systems killed them. Tragically ironic.
Some 50% of your body weight is just bacteria. (So why don’t we lose weight when we take antibiotics – answer that, good doctor!! Now, *that* would be a diet pill!)
Laura will appreciate this: Dr. Schryvers is working on a ‘humanized’ mouse, in order to test antibacterials for us on them, as they wouldn’t work on ‘regular’ mice. I wonder if ‘humanized’ mice will have better manners or worse – we may not be doing them any favours, I think.
