Researchers discover primary sensor that detects stomach viruses

Jul 18, 2008

Scientists at Washington University School of Medicine in St. Louis have identified the primary immune sensor that detects the presence of stomach viruses in the body. They show that the sensor – a protein called MDA-5 – triggers an immune response that revs up the body's defenses to fight off the infection. This knowledge may help develop a treatment that prevents or reduces infection, the researchers suggest in their study, published July 18th in the open-access journal PLoS Pathogens.

The stomach flu is technically not the flu at all: the flu virus only affects the respiratory tract. The stomach flu is known scientifically as a norovirus. Norovirus outbreaks are common in locations where people live close together, such as cruise ships, nursing homes, military bases and schools. Antibiotics are ineffective, because they fight bacteria, not viruses. Only recently have scientists been able to grow noroviruses in the laboratory and study them.

"Our research strongly indicates that MDA-5 is the primary sensor for norovirus infection, but the body's ability to detect the virus is so important that it doesn't just rely on one sensor," says senior investigator Marco Colonna, M.D., professor of pathology and immunology. "We found that another protein sensor – TLR3 – serves as a back-up and there may be others that have not yet been discovered."

The team demonstrated their work in mice but says the same proteins are likely responsible for detecting norovirus infection in humans. MDA-5, and to a lesser extent, TLR3, respond by causing other cells to release interferon, which shuts down production of the virus and initiates a full-scale immune attack. MDA-5 and TLR3 are both intracellular proteins. The researchers suspected that these two proteins may be important in detecting noroviruses because they are known to be important in recognizing similar types of viral infections.

Lead author Stephen McCartney, a graduate student in Colonna's lab, first found that cells in the test tube that lack the MDA-5 protein don't mount an appropriate immune response against norovirus infection.

The team then investigated two groups of mice – one group was bred without the ability to produce MDA-5 and the other was bred to lack TLR3. Again, both groups of mice had a defective immune response against noroviruses. In particular, mice without MDA-5 had higher levels of norovirus in their bodies and a defect in the ability to signal other immune cells to respond. Mice that lacked TLR3 also had a decreased response to norvirus infection, the researchers noted.

Interestingly, some people have common variations of the MDA-5 gene that could make them more susceptible to norovirus infection, the researchers say. A norovirus treatment could be especially helpful to people who are more prone to the infection.

Citation: McCartney SA, Thackray LB, Gitlin L, Gilfillan S, Virgin IV HW, et al. (2008) MDA-5 Recognition of a Murine Norovirus. PLoS Pathog 4(7): e1000108. doi:10.1371/journal.ppat.1000108

Source: Public Library of Science

Explore further: Fatigue, fear are daily lot of Ebola fighters: experts

add to favorites email to friend print save as pdf

Related Stories

Twitter admits to diversity problem in workforce

1 hour ago

(AP)—Twitter acknowledged Wednesday that it has been hiring too many white and Asian men to fill high-paying technology jobs, just like several other major companies in Silicon Valley.

Recommended for you

Fatigue, fear are daily lot of Ebola fighters: experts

40 minutes ago

Doctors, nurses and hospital workers fighting the Ebola epidemic in west Africa are struggling with a daily burden of exhaustion, shortage of staff and fear for themselves over the deadly virus, specialists say.

Hong Kong makes Ebola 'contingency' measures

3 hours ago

Hong Kong said Wednesday it was quarantining all people from Guinea, Sierra Leone and Liberia who were showing Ebola-like symptoms on arrival in the city, as fears grow worldwide about the spread of the deadly virus.

EU ready for Ebola threat: sources

6 hours ago

The European Union is equipped and ready to treat victims should the deadly Ebola virus, which has killed hundreds in West Africa, be found in member states, EU sources said Wednesday.

Reducing kidney injury using a quality improvement method

11 hours ago

Using quality improvement measures in eight of the 10 hospitals in the Northern New England Cardiovascular Disease Study Group, researchers have found a way to reduce kidney injury in patients undergoing a procedure with ...

App for headache sufferers shows success

23 hours ago

A unique app that helps headache sufferers to record the severity and regularity of their pain is being used as part of a Griffith research study.

User comments : 0