A new cancer fighting vaccine could come from an unlikely place. Photo: petfinder.com

A new cancer fighting vaccine could come from an unlikely place. Photo: petfinder.com

Right now, I’m the happy caregiver of seven cats (five kittens. Yey!) which in most people’s books makes me socially challenged and insane. I do take special notice of my pets, and this means looking after them so they don’t get infected by parasites. Cats are typically clean animals, but when infested can spell trouble for family health – ZME cat owners, do be careful! Some cat parasites, however, can prove to be extremely useful if manipulated to our needs. For instance, researchers at the  Dartmouth-Hitchcock Medical Center have mutated a strain of parasite found in cat poop that they used to treat cancer in mice with extremely promising results.

Reversing a nasty parasite to work for us

The parasite in question, Toxoplasma gondii, thrives in the cats intestines and spreads to external environment through the back door. It  is extremely undesirable for a cat to harbor, since it causes illness and can infect both cat and human. A mutated version of T. gondii, called “cps”, has proven to have cancer fighting properties, however.

“We know biologically this parasite has figured out how to stimulate the exact immune responses you want to fight cancer,” explained David J. Bzik, a professor of Microbiology and Immunology at Dartmouth.

“The biology of this organism is inherently different from other microbe-based (treatments) that typically just tickle immune cells from the outside,” said senior research associate Barbara Fox. “By gaining preferential access to the inside of powerful innate immune cell types, our mutated strain of T. gondii reprograms the natural power of the immune system to clear tumor cells and cancer.”

A healthy immune system responds vigorously to T. gondii in a manner that parallels how the immune system attacks a tumor. In response to T. gondii, the body produces natural killer cells and cytotoxic T cells. These cell types wage war against cancer cells. Cancer can shut down the body’s defensive mechanisms, but introducing T. gondii into a tumor environment can jump-start the immune system.

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Lab tests demonstrated the cps is particularly adapted to treating  extremely aggressive cases of melanoma and ovarian cancer in mice. What’s more, the strain is non-replicating, thus safe, and can work its magic even in environments with weak immune systems, as is often the case for chemotherapy patients. Tests have revealed extremely promising survival rates.

“Aggressive cancers too often seem like fast-moving train wrecks,”  Bzik said. “Cps is the microscopic, but super-strong, hero that catches the wayward trains, halts their progression, and shrinks them until they disappear.”

What makes the bacteria particularly effective is the possibility to use it for specifically tailored treatments. Doctors can harvest cells from cancer patients, culture them along with the cps bacteria, then isolate an immunotherapeutic vaccine that generates an immune response specially customized for the patient, just like a Trojan horse.

The research is still in its incipient phase, and researchers are currently tweaking and exposing cps to more tests to get an idea which are its target molecules and mechanisms.

A parasite that might make you insane

While kitty litter might be seen with new eyes, it’s still important to be careful. The same parasite, T. gondii, has been found to drive cat owners literally crazy. T. gondii causes toxoplasmosis,  the leading cause of death attributed to foodborne illness in the United States. More than 60 million men, women, and children in the U.S. carry the Toxoplasma parasite, but very few have symptoms because the immune system usually keeps the parasite from causing illness. Jaroslav Flegr, a Czech evolutionary biologist, claims the parasite is quietly tweaking the connections between our neurons, changing our response to frightening situations, our trust in others, how outgoing we are, and even our preference for certain scents. When you add up all the different ways it can harm us, says Flegr, “Toxoplasma might even kill as many people as malaria, or at least a million people a year.”

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That’s some serious claims, which, as often is the case, had him ridiculed by the scientific community, but there are many voices that believe his research is well conducted and that he’s well on to something. One such voice is Stanford’s Robert Sapolsky, whose findings seem to lend credence to Flegr’s ideas. Sapolsky proved that T. gondii can turn a rat’s strong innate aversion to cats into an attraction, luring it into the jaws of the predator. Basically, it brainwashes the rat, and human owner maybe, to become attracted to the cat.

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