Production and characterization of monoclonal antibodies to three infectious bronchitis virus serotypes.

Three panels of monoclonal antibodies (MAbs) were prepared against the spike (S) proteins of infectious bronchitis virus (IBV) strains Arkansas 99, Connecticut 46, and Massachusetts 41. Based on enzyme-linked immunosorbent assay (ELISA), the MAbs were grouped into three categories: 1) group-specific, which reacted with a broad spectrum of homologous and heterologous IBV serotypes; 2) serotype-specific, which reacted only with strains of the homologous serotype; and 3) strain-specific, which reacted "selectively" with only certain strains of homologous and heterologous serotypes. MAbs that displayed serotype specificity were all specific to S1 fractions of the homologous serotype, confirming that epitopes that determine virus serotype are associated with the S1 protein. An excellent correlation was found when the results of IBV serotyping by MAb-based indirect ELISA were compared with those from the conventional virus-neutralization test. This confirms that the MAbs described here will serve as valuable tools in epizootiological studies and serotype-specific diagnosis of IBV infection.