DEVELOPMENT OF A FLUORESCENT FOCUS IDENTIFICATION ASSAY USING SEROTYPE-SPECIFIC MONOCLONAL-ANTIBODIES FOR DETECTION AND QUANTITATION OF ROTAVIRUSES IN A TETRAVALENT ROTAVIRUS VACCINE

A fluorescent focus identification assay (FFIDA) was developed for use in experimental studies and for quantitation of the components in a t etravalent live oral rotavirus vaccine. The assay utilizes four seroty pe-specific neutralizing monoclonal antibodies (MAb) to detect and qua ntify individual rotaviruses by immunofluorescence staining of fixed v irus-infected monkey kidney cells. In mixed virus infections, all four MAb, W1 (serotype 1), 1C10 (serotype 2), R1 (serotype 3), and S4 (ser otype 4), specifically stain the relevant homologous serotype without exhibiting any cross-reactivity against the other serotypes. Furthermo re, the test is sensitive enough to differentiate at least twofold (0. 3 log) differences in virus titer, The results of testing four individ ual experimental vaccine lots three or more consecutive times showed t hat ail four lots contained similar proportions of the four vaccine st rains as detected by the classical plaque neutralization identificatio n test. The rapidity and efficiency of the FFIDA are desirable attribu tes that make it suitable for use in studies requiring identification and quantitation of one or more of the four major rotavirus serotypes.