Antigenic relatedness between seven avian mycoplasma species as revealed by western blot analysis

Cross-reactivities among seven avian mycoplasma species (Mycoplasma gallisepticum, M. synoviae, M. meleagridis, M. iowae, M. anatis, M. gallinarum, and M. iners) were examined using rabbit polyclonal antisera and two monoclonal antibodies (MAbs) against M. pneumoniae: Myc-9 and Myc-4. The major antigens and cross-reacting antigens of the seven mycoplasma species were demonstrated by immunoblotting assay using homologous and heterologous antisera. Two-way cross-reacting antigens of MS and MG, with apparent molecular weights of 44,000 and 36,000, were identified. Additionally, the 36,000 protein of MG was recognized by all of the heterologous antisera. A large number of cross-reactivities, which have been never investigated before, were shown between M. meleagridis and M. synoviae, between M. meleagridis and M. gallinarum, between M. meleagridis and M. iners, and between M. gallinarum and M. iners. All of the cross-reactions existing between the majority of the above species were considerably reduced or eliminated by adsorbing the polyclonal antisera with a pool of heterologous antigens. Two MAbs against a M. pneumoniae protein of a molecular weight of 150,000 were also able to recognize several avian mycoplasma epitopes, of which two common epitopes with molecular weights of 44,000 and 42,000 were present in most of the seven mycoplasma species.