Scientists say they are a step closer to developing a vaccine against a highly contagious virus that causes outbreaks of winter vomiting.
Good hygiene is important to stop the virus spreading
Although rarely life threatening, there is currently no effective treatment for norovirus.
Up to 1m people catch this stomach bug each year in the UK. It has caused some hospital wards to close temporarily.
Washington University researchers were the first to successfully grow the virus in the lab for testing.
This should make it much easier to learn about the virus and develop ways of combating the disease with antiviral treatments and vaccines, the scientists hope.
Up until now, studies have relied on clinical specimens or materials from people infected with the virus because it has not been possible to grow noroviruses in cell culture.
Outbreaks of norovirus gastroenteritis are common in environments where there is confined contact between large numbers of people - such as in hospitals, nursing homes, schools and cruise ships.
The virus is passed through infected faeces and vomit.
Good hygiene can help stop the virus from spreading, but it is difficult to contain.
Dr Skip Virgin and colleagues were able to grow a version of the virus inside cells from mice.
By looking at the mouse virus, they were able to identify the part that is essential to its ability to cause disease.
This was the virus' protein shell called the capsid.
"If this part of the capsid has an equivalent in human noroviruses, altering or disabling it may give us a way to produce forms of the viruses that are weak enough to serve as vaccines," said Dr Virgin.
The researchers believe cells within the human gut are the site where the virus enters the body to cause disease.
They will publish their findings in the journal Public Library of Science - Biology.
Professor Ian Clarke, professor of virology at Southampton University, said: "It's a brilliant discovery.
"The Holy Grail of that research is to grow the virus in cell culture because that's the real breakthrough that allows you to understand more about how the virus works.
"This is a significant advance, even though it is in mice.
"It is a model with which to work out how to study the human virus.
"Ultimately, it could lead to the development of antiviral treatments and perhaps vaccines. That's a long way off."
So far this year, including the winter months at the start of the year, there have been 160 outbreaks of infectious gastroenteritis due to norovirus, compared to 220 outbreaks in the whole of 2003, according to the UK's Health Protection Agency.
A spokesman from the HPA said: "The identification of a mouse norovirus and a culture system in which it grows offers insights into the cultivation of human noroviruses.
It will allow work on the effects of disinfectants, cleaning regimes, antiviral drugs and possible vaccine candidates to be accelerated."