CROSS-REACTING LIPOPOLYSACCHARIDE ANTIGENS IN LEGIONELLA-PNEUMOPHILA SEROGROUPS 1 TO 14

Immunological cross-reactions among Legionella species were investigat ed with sonicated, proteinase K-digested cell lysates. The antigens se parated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis w ere either analyzed for lipopolysaccharides (LPSs) by silver staining or transferred to nitrocellulose membranes for serological characteriz ation with rabbit antibodies directed against Legionella pneumophila s erogroups 1 and 5. When antiserum prepared against serogroup 5 was use d to probe the LPSs from L. pneumophila serogroups 1 to 14, the antibo dies recognized a common epitope harbored by all L. pneumophila serogr oups hut not by other Legionella species or by the gram-negative bacte ria tested as controls. Hence, the serogroup 5 antiserum correctly ide ntified all serogroups of L. pneumophila tested in the LPS immunoblot assay. Moreover, the silver-stained profiles of the isolated LPSs reve aled characteristic patterns allowing the identification of the indivi dual serogroups of L. pneumophila.