During an outbreak of smallpox 100 years ago, a group of doctors treating patients also suffering from lymphomas noticed a puzzling occurrence: Many patients fortunate enough to survive the smallpox infection were twice blessed, as they saw their cancerous tumors disappear as well.
It was an observation doctors didn't understand at the time, and so the incident was filed away for decades under the category of peculiar.
Today, researchers are beginning to understand just what happened. Viruses, once thought to bring nothing but sickness to their hosts, can also be harnessed and used as weapons against killers like cancer.
It's a 180-degree turn that has shifted the way scientists now look at the pathogens. A decade ago, most research was simply concerned with how viruses entered normal cells, how they replicated and how they fought.
"The point used to be we need to understand our enemies," said molecular virologist Dr. Valery Grdzelishvili, an assistant professor in UNC Charlotte's biology department. "If we don't know how they do it, how can we fight HIV, hepatitis C and other very bad viruses?"
Today, with the new understanding that some viruses act like kryptonite to certain cancer cells, many researchers like Grdzelishvili are more interested in finding ways to take advantage of cancers' weaknesses through viral therapy.
"Most cancer cells - not 100 percent but maybe 80 percent to 85 percent of different kinds of cancers - have defective anti-viral responses," said Grdzelishvili.
In the molecular virology lab at UNCC, Grdzelishvili studies the effects of viruses on pancreatic cancer cells. It's a collaboration with Dr. Pinku Mukherjee, who runs a neighboring lab focused on the treatment of pancreatic and breast cancers.
The payoff could lead to viral therapy joining the arsenal of other cancer-fighting tools like radiation, chemotherapy, and surgery.
Although the idea of using viruses as treatment for cancer has caused some public worry, the viruses used in viral therapy are non-pathogenic to humans, and generally the kind that target other species.
In truth, only a few viruses, like HIV and hepatitis C, actually pose serious threats to humans. The thousands of other viruses that lurk around us on doorknobs and shopping cart handles cause little harm, and many more viruses are already inside our bodies on any given day.
"You are infected with most likely several viruses at the same time every moment of your life," said Grdzelishvili. "We have a good immune system so our body can handle 99 percent of viruses."
The use of viruses in medical science is not an entirely new approach. In clinical trials, gene therapy researchers use the parts of a virus that make it such a good invader to deliver good genes into the body where faulty ones exist.
In clinical trials, disorders like cystic fibrosis, which is caused by a single mutation in a gene, are being studied through viral therapy.
"They make a virus that cannot replicate, cannot cause infections," said Grdzelishvili. "They insert a good gene using the virus' ability to get to certain tissue."
Viral therapy for use in cancer patients is still a few years away. Health regulations and other aspects of getting a new medicinal product on the market create a slow process, often taking 10 to 15 years.
"As of today, only one virus is approved for clinical use," said Grdzelishvili. "It was developed in the United States and was approved for use in China on different cancers."