A murine monoclonal antibody defines a unique epitope shared by Klebsiella lipopolysaccharides.

A hybridoma secreting a monoclonal antibody (MAb) directed against Klebsiella lipopolysaccharide (LPS) was derived from spleen cells of mice immunized a smooth, nonencapsulated Klebsiella strain (Friedländer 201; serogroup O1). The MAb, called V/9-5 (immunoglobulin G2a), cross-reacted with LPS preparations produced from reference strains for the Klebsiella O serogroups O1, O2ab, O2ac, O3, O4, O5, and O12. Furthermore, the MAb reacted with LPSs from serogroup reference strains O6/O8, O9, and O11, which are regarded as being identical to O1, O2, and O4, respectively. When testing the supernatant of clinically isolated Klebsiella strains by means of an inhibition enzyme-linked immunosorbent assay, we found that 86 (92.4%) of 93 Klebsiella pneumoniae subsp. pneumoniae isolates and 24 (96.0%) of 25 K. oxytoca isolates harbored the cross-reactive epitope. By contrast, two laboratory strains of K. pneumoniae subsp. rhinoscleromatis did not react with MAb V/9-5. The MAb proved to be specific for the genus Klebsiella, since it did not react with any of a total of 73 strains belonging to other gram-negative bacterial genera. In conjunction with other LPS-specific MAbs, MAb V/9-5 might become a useful reagent for rapid identification of klebsiellae in clinical specimens. Furthermore, the epitope recognized by MAb V/9-5 might serve as a target epitope for the production of human MAbs for immunotherapeutic purposes.