THE 64-KDA LIPOPROTEIN OF MYCOPLASMA-GALLISEPTICUM HAS 2 DISTINCT EPITOPES RESPONSIBLE FOR HEMAGGLUTINATION AND GROWTH-INHIBITION

A major Mycoplasma gallisepticum polypeptide of 64 kDa (p64) was chara cterized using two distinct monoclonal antibodies (MAbs), MAb K1 produ ced in our laboratory and MAb MyG 001 produced by Avakian & Ley (1993) . The p64 antigen was shown to be a lipoprotein in a radioimmunoprecip itation assay using [H-3] palmitic acid-labelled M. gallisepticum cult ures. The two MAbs inhibited the growth of M. gallisepticum in liquid medium and reacted to two distinct epitopes on the same p64 antigen in competitive enzyme-linked immunosorbent and chemiluminescence Western immunoblot assays. MAb K1 inhibited haemagglutination of chicken and turkey erythrocytes whereas MAb MyG 001 did not. The results of our st udy indicate that p64 has two distinct epitopes involved in haemagglut ination and growth inhibition of M. gallisepticum, MAb K1 also inhibit ed the attachment of the mycoplasma to TLT lymphoblastoid chicken B ce ll line, suggesting that p64 is a cytadhesin.