 The primary objectives are to evaluate the safety and reactogenicity of the norovirus GII.4 CIN-1; 031693 challenge stock and to determine a safe and optimal challenge dose of Norovirus GII.4 Challenge Stock norovirus to achieve illness in 50 of subjects. Illness is defined as: diarrhea 3 loose or liquid stools or 300 gm of loose or liquid stool 24h, andor vomiting during the inpatient period, in a participant with evidence of infection. The secondary objectives are to determine the rate of infection in study participants by; virus detection in stool by Norovirus GII.4 Challenge Stock-specific qRT-PCR and anti- Norovirus GII.4 Challenge Stock serum IgG by ELISA 4 fold rise from baseline to Day 30, determine the quantity and duration of virus shedding in stool by qRT-PCR, conduct Time-to-event analysis to estimate the median time to cessation of shedding using Kaplan-Meier methods, determine the modified Vesikari score as a measure of gastroenteritis severity, determine Norovirus GII.4 Challenge Stock-specific immunoglobulin titers by ELISA before and after the challenge; Serum IgA and IgG, Serum Blockade IgG, Salivary IgA, determine the effect of preexisting Norovirus GII.4 Challenge Stock-specific Immunoglobulin in serum and saliva on the rate of infection, determine total and Norovirus GII.4 Challenge Stock-specific IgA- and IgG-Secreting Cells in circulation by ELISpot assay. 