Efficient coating of the solid phase with rotavirus antigens for enzyme-linked immunosorbent assay of immunoglobulin A antibody in feces.

Sensitivity of the enzyme-linked immunosorbent assay for detecting serum antibodies to rotavirus was greatly enhanced when rotavirus particles were fragmented by chaotropic agents (NaSCN or guanidine hydrochloride) before adsorption of the antigens to the solid phase. For detecting fecal antibodies, the addition of fetal calf serum to the diluent was further needed to protect the antigens from the proteolytic activity of feces. With this technique, we readily detected immunoglobulin A antibody in feces from infantile gastroenteritis patients. Rate-zonal centrifugation of feces revealed that immunoglobulin A antibody activity sedimented with two peaks: one at 11S with a secretory component and another sedimenting slower than 7S, presumably as Fab portions.