Mycoplasmas are the smallest known free-living organisms and include genetically diverse pathogens causing a variety of chronic pulmonary, genitourinary and rheumatologic disorders in animal species, including man. Immunologic mechanisms are strongly implicated in mycoplasma pathogenesis, and substantial information has been gained pertaining to specific antigenic structures of potential disease relevance. In addition, antigenic relationships among species of pathogenic mycoplasmas may define products expressed from related genomic regions of this organism. These structures are important because they may offer a means of immunologically detecting specific genetic relationships in organisms highly refractory to classic genetic analysis. The long term objective of this proposal is to identify and characterize mycoplasma genomic structures that synthesize selected antigens in order to (1) obtain genetic and structural information on selected antigens of relevance to mycoplasma immunopathology, (2) define antigenic and corresponding genomic relationships among mycoplasma species, and (3) investigate the physical organization of the mycoplasma genome. The organism proposed for this study is Mycoplasma hyorhinis, an arthritogenic pathogen that has been extensively studied in vitro to elucidate many molecular and immunological details of the mycoplasma-host cell interaction. This organism is antigenically related to a large group of mycoplasmas including numerous pathogenic species. An established library of recombinant bacteriophage containing segments of the 750 kbp genome of M. hyorhinis will be screened by recently developed immunological, immunochemical, and molecular biological procedures to identify, catalogue, and characterize mycoplasma genomic sequences encoding antigens expressed in the bacterial host Escherichia coli. The library will be screened with a large existing library of monoclonal antibodies directed against preselected specificities of important disease relevance, as well as polyclonal antibodies recognizing antigens shared among species, and serum from arthritic animals to define immunodominant antigens during disease. Antigens expressed from selected recombinant genomic sequences, will be further characterized and the genomic structures themselves will be used to generate specific probes capable of detecting species-specific or species-shared genomic sequences in a cluster of antigenically related pathogenic mycoplasmas.
