Comparative efficiency of commercial immunoassays for the diagnosis of rotavirus gastroenteritis during the course of infection.

We evaluated the performance characteristics of three commercially available immunoassays for the detection of rotavirus antigens in stool samples obtained from infants during the course of rotavirus gastroenteritis. Two of the assays, Bio-EnzaBead (Litton Bionetics, Charleston, S.C.) and Rotazyme (Abbott Laboratories, North Chicago, Ill.), are enzyme immunoassays, while the third, Rotalex (Medical Technology Corporation, Somerset, N.J.), is a latex agglutination assay. We tested a total of 122 samples obtained from 26 children with gastroenteritis; 56 samples, obtained from 21 children, were found to contain rotavirus antigen by a reference microplate enzyme immunoassay. Rotavirus antigen was found by the Bio-EnzaBead, Rotazyme, and Rotalex assays in 53, 42, and 29 samples, respectively. The true positivity of samples which were positive by the reference microplate assay but negative by the other assays was confirmed by a specific neutralization assay or by the visualization of bands of double-stranded RNA by polyacrylamide gel electrophoresis or both. No false-positive assay results were noted with any of the commercial assays. The sensitivity of the assays was determined to a great extent by the time after the onset of illness at which the specimen was collected. Thus, the sensitivity of commercial assays with specimens collected early in the course of illness did not differ significantly from that of the microplate assay. However, significantly lower degrees of sensitivity were noted later in the course of illness. Results of our studies indicate that all three commercial assays can accurately detect rotavirus in stools from children with rotavirus gastroenteritis. However, the choice of assay systems for use in the clinical laboratory will depend on the conditions in which stool specimens are collected and tested in the laboratory.