INHIBITION OF MYCOPLASMA-GALLISEPTICUM GROWTH AND ATTACHMENT TO CHICKTRACHEAL RINGS BY ANTIBODIES TO A 64-KILODALTON MEMBRANE-PROTEIN OF MYCOPLASMA-GALLISEPTICUM

A Mycoplasma gallisepticum (MG) strain R protein of 64 kilodaltons (p6 4) was partially digested from the surface of the bacterium by trypsin . Monospecific polyclonal anti-p64 IgG inhibited attachment of MG to c hick tracheal rings by as much as 69%. However, trypsin treatment of v iable MG cells did not reduce attachment to tracheal rings or hemagglu tination titer. Anti-p64 IgG inhibited growth of MG strain R in broth and on solid media, inhibited the uptake of radiolabeled thymidine, bu t did not inhibit hemagglutination. Anti-p64 IgG inhibited growth of e ight MG strains on solid medium. The degree of growth inhibition varie d widely depending on the strain and correlated positively with the re ported virulence of the MG strains with one exception (A5969). An IgG monoclonal antibody to p64 (MyG 001) inhibited growth of MG strain R o n solid and in broth media. The strong attachment-inhibition activity of anti-p64 IgG may result from its growth-inhibiting activity. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of MG strains sugg ested that p64 is expressed in higher amounts in vitro in virulent str ains (R, S6) than in strains of low virulence (F, M876, K503, K703, K7 30). P64 should be used to immunize chickens to determine if it can st imulate a growth and attachment-inhibiting response in the respiratory tract.