Feb 13, 2007 (CIDRAP News) – A team of researchers has achieved what has been until now a frustratingly elusive goal: a tissue-culture model that allows natural growth in the lab of norovirus, one of the most common and least understood causes of gastrointestinal illness worldwide.Though it causes up to 23 million cases of illness each year, according to the Centers for Disease Control and Prevention (CDC), surprisingly little is known about how the virus attaches to and replicates within cells. The new work by Timothy Straub of the Pacific Northwest National Laboratory and collaborators from Tulane University, the University of Arizona, and Arizona State University should change that: They produced a three-dimensional culture of multiple cell types that mimics the epithelium of the human small intestine, and induced norovirus samples isolated from patients to grow and replicate in it.”This is an important result,” said Craig Hedberg, PhD, associate professor of environmental health sciences at the University of Minnesota School of Public Health. “Up until this point, we have never had a direct measure that would allow us to know how effective any of our environmental prevention measures are against norovirus. There have been a lot of studies looking at things that might be able to kill norovirus and render foods and environmental surfaces safe from contamination, but they have always used surrogates.”Norovirus has been a difficult organism to study because, like other viruses but unlike bacteria, it will not reproduce in a simple growth medium. Instead, it requires a tissue culture resembling cells in the organisms it infects.That lack of a lab model for studying the virus has kept testing protocols, effective sanitizing and control measures, and even newer diagnostic tests out of reach. Those are important because norovirus causes such a high disease burden: It is thought to be responsible for at least half of all foodborne outbreaks of gastroenteritis every year, according to the CDC.”Nobody knows what the incidence of this disease is in the population because it is not easy to diagnose—it is just one of the range of ‘stomach flus’ that people get,” said David Ozonoff, PhD, emeritus chair of the department of environmental health at Boston University School of Public Health. “But it causes very substantial economic loss, because so many people stay home from work because they are sick or their kids are.”To create the model, Straub and collaborators grew human intestinal epithelial cells on collagen-coated microbeads that were tumbled in a rotating reactor vessel. They used the resulting tissues for five passages of two genotypes of norovirus that were originally isolated from patients during outbreaks on a cruise ship and in a nursing home, and proved the presence of norovirus by multiple assays following each passage.The work, which will be published in the March edition of Emerging Infectious Diseases and was posted online ahead of print, represents the first lab model of human norovirus infection; previous models used mouse noroviruses or a related feline virus. Scientists not involved in the research said it could point the way to a better understanding of an under-appreciated pathogen.The authors write that developing a method for culturing human norovirus in the lab was a necessary first step in the effort to understand the virus’s pathogenesis. In future research with the model, they hope to identify protective immune responses and learn more about how the virus replicates, with the aim of devising better prevention measures.Norovirus spreads through the fecal-oral route, via both food and water, but there are also indications that it can spread via environmental contamination and direct person-to-person transmission, according to the CDC.It is fiercely contagious: Ingesting as few as 10 virus particles can cause infection, and infected persons can shed virus for up to two weeks after symptoms end, the CDC says. The illness is miserable, with nausea, diarrhea and vomiting multiple times per day. Symptoms usually last from 24 to 60 hours.”Beyond the nuisance value to the individual, it is such a widespread illness and so persistent in institutional settings where you’re dealing with immune-compromised populations that it becomes an important public health problem,” Hedberg said.The CDC does not conduct routine surveillance for norovirus, so there is no way to confirm how commonly the bug occurs. So far this year, however, large outbreaks have been reported at the Scripps Research Institute in California, at Radford University in Virginia, among customers of a south Florida restaurant, in hospitals in Saskatchewan, Massachusetts, and North Carolina, and among hundreds of passengers on the ocean liner Queen Elizabeth 2.The Hilton Hotel near Dulles International Airport outside Washington, D.C. was hit so hard in mid-January, with 120 guests and staff sick, that it was forced to close for a floor-to-ceiling sanitizing. Some norovirus outbreaks, such as on cruise ships, have recurred despite repeated rounds of aggressive cleaning.Straub TM, zu Bentrup KH, Coghlan PO, et al. In vitro cell culture infectivity assay for human noroviruses. Emerg Infect Dis 2007 Mar; 13(3) (early online publication) [Full text]See also:CDC information on norovirushttp://www.cdc.gov/ncidod/dvrd/revb/gastro/norovirus-factsheet.htm
Premier League stars feel that their clubs are trying to influence them with unethical behaviour as teams gear up for the crucial Project Restart vote next week. Premier League fixtures are currently suspended until April 30 due to the coronavirus crisis ( Top-flight chiefs have desperately been trying to find a way to return to action, despite hundreds of people still being killed by coronavirus every day in the United Kingdom. And according to the Mail, Premier League stars are growing increasingly “wary of their employers’ motives”. This is a crucial week for the league, as it tries desperately to get the show back on the road in order to avoid devastating financial consequences. But while Premier League officials are all hoping to get things back up and running, not every club feels the same way. In fact, different clubs appear to hold different party lines, with a divide opening between the top and the bottom. And it has even been suggested that players feel that it has been hinted that they could benefit from new contracts if they adhere to their club’s stance. Loading… Clubs are also trying to get their senior pros to rally their players, whether that be over Project Restart, or taking wage reductions. Players will have to sign a Covid-19 code of practice before any resumption. But there is talk that teams that aren’t keen on the plans to return, are encouraging sceptical players not to sign them. Enough players not signing up would derail the plans entirely. And while top clubs are fine with this, desperate to get the season finished, many clubs still threatened by relegation feel that it threatens the integrity of the competition to surrender home advantage. read also:Bid to replace Ndidi: Leicester battle Inter for Real Betis star The earliest possible vote on Project Restart would be next Monday. Meanwhile, the Premier League meet today to discuss a number of topics, including Boris Johnson’s address last night and potential changes to the transfer window – as well as Project Restart. FacebookTwitterWhatsAppEmail分享 Promoted ContentPlaying Games For Hours Can Do This To Your BodyPretty Awesome Shows That Just Got Canceled10 Phones That Can Work For Weeks Without RechargingBirds Enjoy Living In A Gallery Space Created For Them5 Of The World’s Most Unique Theme ParksCan Playing Too Many Video Games Hurt Your Body?6 Ridiculous Health Myths That Are Actually True5 Of The World’s Most Unique Theme Parks10 Risky Jobs Some Women DoMind-Bending Technology That Was Predicted Before It Appeared13 kids at weddings who just don’t give a hootWho Is The Most Powerful Woman On Earth?