A search through decades-old frozen infant stool samples has yielded rich dividends for scientists from the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health. The team customized a laboratory technique to screen thousands of samples for norovirus, a major cause of acute gastroenteritis outbreaks in people of all ages. What they discovered about the rate of evolution of a specific group of noroviruses could help researchers develop specific antiviral drugs and, potentially, a vaccine against a disease that is very unpleasant and sometimes deadly.
The research, led by Kim Y. Green, PhD, and Karin Bok, PhD, of NIAID's Laboratory of Infectious Diseases, will appear in a future issue of the Journal of Virology. NIAID scientist Albert Z. Kapikian, MD, is a co-author on the paper. In 1972, Kapikian and colleagues identified and characterized the virus, now known as norovirus, responsible for an outbreak of acute gastroenteritis in Norwalk, Ohio in 1968.
"Thanks to the foresight of Dr. Kapikian and others at NIAID and the Children's National Medical Center who established and have maintained these clinical samples since 1974, our researchers have a unique resource that represents one of the oldest sets of norovirus samples in the world," says NIAID director Anthony S. Fauci, MD. "This is the first study to look at samples that date back almost to the first recorded cases of norovirus outbreaks, more than 40 years ago."
Highly contagious, noroviruses are responsible for an abrupt onset intestinal ailment also called winter vomiting disease or cruise-ship disease. The Centers for Disease Control and Prevention (CDC) estimates that 23 million cases of acute gastroenteritis each year are due to norovirus infection and that noroviruses are the cause of more than half of all food borne gastroenteritis outbreaks. In elderly people, infants and people with compromised immune system function, dehydration resulting from vomiting and diarrhea following norovirus infection can be life-threatening. In developing countries, according to a 2008 estimate by CDC researchers, up to 200,000 children under 5 die of norovirus infection each year. There is no vaccine against norovirus and no specific antiviral drugs to treat infections.
A key question for norovirus researchers is determining when a dominant variant, called genotype II.4 (or GII.4), first emerged, notes Green. " This genotype has been associated with the majority of global outbreaks of acute norovirus gastroenteritis since the mid-1990s," says Green. " The GII.4 genotype was first described around 1987, but no one knew for sure whether that genotype emerged then or if it existed earlier."
