Rapid titration of bovine, caprine and human RS virus by a micro-immunoperoxidase assay using a monoclonal antibody and a permissive ovine kidney cell line.

An indirect immunoperoxidase micro-assay, using a continuous cell line derived from ovine kidney cells (OK) and a previously characterized monoclonal antibody (7C2), specific for an exposed and highly conserved epitope of the fusion protein of different strains of RS virus, was used advantageously to rapidly titrate bovine, caprine and human strains of RSV by either quantal (TCID50) or plaque forming assays. Virus titers, obtained in less than 36 h, were in agreement with those obtained by the conventional plaque assays which required an incubation period of 4 days or more. This assay is also applicable to micro-neutralization of fusion inhibition assays for testing serum or screening monoclonal antibodies.