1. Detection of Rotavirus-specific IgA and IgG will occur by ELISA. Detection of rotavirus-specific IgA and IgG will occur by ELISA. Briefly, the procedure is as follows. Microplate wells (e.g., Nunc Immuno I) are incubated with purified viral antigen preparations, then washed with phosphate buffered saline with Tween detergent (PBS-T). Serum and breast-milk samples are diluted serially (in PBS-T containing 1% bovine serum albumin) and incubated in the coated microplates for 2 hours at 37oC then overnight at 4oC. Microplates are then washed and peroxidase-conjugated anti-human IgA or IgG goat antibodies (Sigma Immunochemicals) is added. The reaction is then terminated with H2SO4, and optical density is measured by EIA plate reader. All samples are assayed in duplicate against each viral antigen and against a control antigen. A test well was considered positive by its optical density at 450 nm, e.g., if it is greater than or equal to two times that of its own control. Specificity is controlled by including wells containing control antigen incubated in the absence of the sample, and sensitivity is checked by including wells containing viral antigen incubated in the presence of samples known to contain high titre of a particular rotavirus-specific immunoglobulin class.