<qa>  What is the name of the group that will be challenged orally with a NorovirusDescription of Study Design: Healthy volunteers with different blood types and low antibody titers to the challenge strain will be challenged orally with a Norovirus in the CCCR inpatient facility. Subjects with resistant non-secretors or susceptible secretors of either A, B or O blood group to the challenge strain will be recruited. The challenge study will be conducted in two groups of twenty, each with approximately ten secretors and ten non-secretors. Three additional subjects per group will serve as alternates in the event that any of the study subjects are unavailable or become ineligible at the time of the inpatient study. Subjects will be monitored daily in the isolation facility for at least five days following this challenge for daily clinical and virological evaluations. Subjects will return to the investigational site for evaluation the day after discharge from the inpatient unit and about 30 days 28-35 days post challenge. 