Researchers isolate human monoclonal antibodies that may neutralize several norovirus variants Researchers at Vanderbilt University Medical Center (VUMC) and the Baylor College of Medicine in Houston, Texas, have taken a big step toward developing targeted treatments and vaccines against a family of viruses that attacks the gastrointestinal tract. Each year in the United States circulating strains of the human norovirus are responsible for approximately 20 million cases of acute gastroenteritis. Hallmark symptoms include severe abdominal cramping, diarrhea and vomiting. Several vaccine candidates are in clinical trials, but it is unclear how effective they will be, given the periodic emergence of novel norovirus variants. Developing broadly effective vaccines will require an understanding of the genetic diversity of the virus and the mechanisms by which the immune system can neutralize it.