GENOMIC, PROTEIN AND ANTIGENIC VARIABILITY OF MYCOPLASMA-BOVIS

Restriction endonuclease analysis (REA) with three enzymes SmaI, PstI, BamHI- was used to identify 13 different genomic groups among 37 Myco plasma bovis strains. One genomic group was comprised of 14 strains. S odium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) pa tterns for one strain chosen from each genomic group and an internatio nal reference strain PG45 were all similar. Antigenic variability in M . bovis species was investigated by immunoblotting, using serum from a calf that had been naturally infected with M. bovis and three M. bovi s-specific monoclonal antibodies - mAbs N-2, I-2 and 5D7. Twenty M. bo vis field strains were tested, comprising one from each genomic group, six from the same genomic group and the reference strain. Antigenic p rofiles obtained with calf serum differed markedly one from the other, the heterogeneity being equally great among the strains belonging to the same genomic group as those coming from different groups. A stable antigen common to 164 out of 168 strains was detected by mAb N-2, whi lst with mAbs I-2 and 5D7, two different membrane antigenic systems we re demonstrated that were strikingly variable. These variations in exp ression occurred not only from one strain to another, but also within the same lineage of clones from a single cell.