Aiming to the evaluation of antigenic relationships among isolates of infectious bronchitis virus (IBV) through their reactivity against Massachusetts M41 S1 glycopolypeptide specific monoclonal antibodies (Mab) an ELISA was developed. Fourteen IBV isolates obtained from field cases of disease, reported from 1972 to 1989 in Minas Gerais, Brazil, were examined. The IBV isolates could be grouped into related or not to M41, based on the reactivity to M41 S1 specific Mabs. The unrecognized field isolates conform a diversity of representatives, which may range from Massachusetts vaccine strains to unrelated heterologous IBV serotypes. The detection of three M41-related isolates (208-1972, PM1-1987 and PM2-1987) indicate that, despite the high variability and pressure for changes in the S1 protein, M41 clones are still present in the field and may point out that the survival strategies for isolates should include mechanisms that preserve the best fits for cellular receptors.
Chicken; infectious bronchitis virus (IBV); M41; field isolate; ELISA; Brazil
