Human rotavirus and its antibody: their coexistence in feces of infants.

Rotavirus and its antibody were detected by paper disk solid-phase radioimmunoassay or electron microscopy in feces of infants and young children with acute diarrhea. The fecal specimens in which rotavirus was detectable often contained a high titer of antibodies, which were shown by radioimmunoassay to belong mainly to the immunoglobulin G class. Rotavirus was rarely detected in the specimens containing immunoglobulin A antibodies. By dissociation tests carried out by radioimmunoassay, it was shown that the rotavirus particles in some specimens had the same antibody-binding capacity as did cultured simian rotavirus (SA-11), but antibodies in feces usually had low avidity, probably resulting from enzymatic digestion.