Have you ever heard of norovirus?
We may be closer than ever to ending those miserable days of vomiting, diarrhea and harsh fever after eating contaminated food or shaking the wrong person’s hand. A research discovery at UNC-Chapel Hill could help tackle stomach flu.
Epidemiology research specialist Lisa Lindesmith and professor Ralph Baric of UNC’s Gillings School of Global Public Health discovered an antibody that could lead to a vaccine that helps people’s immune systems attack the dreaded norovirus, even when it changes into new strains. An antibody is a protein that is essentially the weapon that immune systems use to fight viruses and bacteria.
The highly contagious human norovirus causes food poisoning outbreaks that can be deadly. Many people call it the stomach flu or bug, and it spreads like wildfire in schools, hospitals, cruise ships and military bases where people are confined.
Norovirus causes more than 200,000 deaths, mostly young children and elderly, around the world each year, according to the Centers for Disease Control and Prevention. It is the leading cause of acute gastroenteritis, which is the inflammation of the stomach and intestines.
It infects more than 20 million people in the United States annually. And Lindesmith notes that this a low estimate because many people don’t see a doctor and ride out their misery at home in bed.
UNC’s antibody discovery
Typically, your body sends a swarm of many different antibodies to attack a virus all over. But our immune systems struggle because a virus is constantly changing.
That can make finding an effective vaccine difficult.
This discovery will help scientists design a vaccine that focuses the human immune response to use more of the right weapons to attack a specific region of the virus that doesn’t change. The researchers found an antibody that binds to a part of the norovirus that stays constant.
Baric said imagine the virus is protected by a mountain range and your immune system is searching for the virus’ critical vulnerable site. This antibody is the path to that site.
Now, there’s a target for developing a vaccine that offers long-term protection, because a person’s immune system can see the virus and attack it, even when the virus changes. And the antibody itself could also help develop a therapeutic drug for treatment.
There are many different strains and types of norovirus that cause outbreaks. The strain these researchers are attacking, the GII4 strain, is responsible for 60 percent of all outbreaks and causes all of the serial pandemics that have come around every two to seven years since the mid-’90s.
Serial pandemics come when the virus changes form, making a new strain and rendering current vaccines useless for protection. It’s about time for another pandemic to occur, Lindesmith said, likely this winter.
“Right now we just experience [serial pandemics],” Lindesmith said, “but now that we know where to watch on the virus ... we have a better understanding of what to expect and when we should get concerned.”
Human clinical trial
The 3-year study was published in the June 18 issue of Immunity, a monthly peer-reviewed medical journal of immunology. UNC researchers partnered with Takeda Vaccines, a leading vaccine manufacturer, and researchers at the University of Texas at Austin, the National Institutes of Health Vaccine Research Center and the CDC.
The researchers analyzed three human subjects to isolate and identify these antibodies. The samples came from Takeda Vaccines’ human clinical trial that involved hundreds of adults. Their study is currently in phase 2b and is leading the way in developing a human vaccine.
Another benefit to this finding is that while the experimental vaccination was given to the adults, this antibody wasn’t introduced by the vaccine. It was already in the people’s bodies, and the vaccination simply boosted the number of those antibodies.
That’s encouraging, Baric, said because most of the severe cases of norovirus are either in really young children or people over 65. This shows they’re close to providing effective treatment for adults. The next step will be testing its effectiveness in children.
Impact beyond norovirus
This discovery could be revolutionary in curing or treating other viruses because of the researchers’ approach, said Lindesmith, who’s been studying norovirus with Baric since 1999. The way they were able to isolate, define and characterize these antibodies in the norovirus could be applied to others.
Their work creates a template for how to develop a vaccine that will combat the complexity and adaptive nature of viruses, including those that cause the flu and HIV.
Lindesmith said their method of targeting the unchanging segment is the “holy grail for vaccine design.”
“The platform we used to do that is very translatable,” Lindesmith said. “Pick your pathogen.”
With this discovery, the hope is that future vaccines wouldn’t have to change or they would last much longer because their target isn’t changing, Lindesmith said.
“It should buy you much more time.”