ISOLATION OF A LEGIONELLA-PNEUMOPHILA STRAIN SEROLOGICALLY DISTINGUISHABLE FROM ALL KNOWN SEROGROUPS

A Legionella pneumophila strain (Jena-1) was isolated from a water sam ple collected from the hot water system of a scientific institution in Jena, Germany. Protein profile, ubiquinone and fatty acid content of the outer membrane were in accordance with those described for other L egionella pneumophila serogroups. DNA extracted from strain Jena-1 gav e a positive amplification by using an L. pneumophila (mip)-specific c ommercially available PCR-kit confirming that the isolate belonged to the species L. pneumophila. Strain Jena-l reacted with a monoclonal an tibody specific for the major outer membrane protein of the species L. pneumophila and another one recognizing a lipopolysacharide epitope o f L. pneumophila serogroups 2-6, 8-10, and 12-15. Cross-absorption stu dies using absorbed and unabsorbed rabbit antisera to serogroups 1-15 and the newly isolated strain showed that strain Jena-1 cross-reacted mainly with serogroup 4, and to a lesser extent, with serogroups 5, 8, and 10. These cross-reactions could be removed by cross-absorption wi thout significant effects on the homologous titres. It is concluded th at strain Jena-1 represents a new serogroup of Legionella pneumophila.