Prof Using DNA Technology to Improve Public Health

July 27, 2011 - News Release

Your dog’s mouth is cleaner than your own, right? Wrong, says a University of Guelph professor who has used cutting-edge DNA technology to show that your canine pet’s mouth harbours as many kinds of bacteria as your own.

Scott WeestThat’s just one example of public health-related research into microbes in dogs, horses, cats and people afforded by a “next-generation” DNA sequencing machine now being used by Scott Weese, a pathobiology professor in U of G’s Ontario Veterinary College.

The instrument — about as big as a computer printer — tells researchers which species of bacteria are in samples with complex bacterial populations, such as those in the GI tract. That’s an improvement over the meticulous and time- consuming work of examining individual sample slides, said Weese.

And unlike earlier machines that look for DNA of only one microbial species at a time, this next-generation device can sift through samples to quickly tell him the full range of bugs in the gut or mouth.

Weese and other researchers are using the machine to examine gut microbes in various animals — and to overturn a few public-health myths in the process.

Looking at dog saliva samples, he and his grad student Jason Stull found more than 100 species of microbes, about as many as in human saliva. Some can cause serious disease in people, especially children and elderly people or people on drugs that suppress their immune systems, said Weese. “I’d say the idea that a dog’s mouth is cleaner is a myth.”

He suggests people avoid being licked by dogs and wash their hands after handling pets, although he adds that the overall risk of infection is low.

In the first comprehensive survey of its kind, he has looked at gut flora in horses, especially horses with and without diarrheal diseases. His study found a wider range of microbial species in the normal equine gut than researchers had known about earlier, as well as lowered diversity in diseased horses.

Weese said his studies suggest veterinarians should treat illness by improving gut microbe diversity — perhaps through feeding supplements as in human probiotics — rather than using antibiotics to kill one or two target species. “The gut is a complex, dynamic system. We need to figure out what’s going wrong and what works.”

Weese holds the Canada Research Chair in Zoonotic Diseases. He also belongs to U of G’s Centre for Public Health and Zoonoses (CPHAZ), a group of researchers and agencies helping to control animal-related diseases that threaten human health, from bird flu to E. coli O157:H7.

The new DNA sequencer will be located in a new CPHAZ facility at OVC that will open in the fall. Said PhD student Marcio Costa: “This is cutting-edge research that we do with this machine. We need to control disease in animals to control transmission to people.”

Prof. Scott Weese
Centre for Public Health and Zoonoses
519-824-4120, Ext. 54064 or 54721

For media questions, contact Communications and Public Affairs: Lori Bona Hunt, 519-824-4120, Ext. 53338,; or Shiona Mackenzie, Ext. 56982,

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