A monoclonal antibody with specificity for the genus Klebsiella binds to acommon epitope located in the core region of Klebsiella lipopolysaccharide

A mouse monoclonal antibody (mAb) which has been obtained after immunizatio n of mice with heat-killed Klebsiella pneumoniae strain R20/Ol(-) followed by standard plasmacytoma cell fusion protocols was investigated for its abi lity to identify various species of the genus Klebsiella. Based on the publ ished observation that the antibody binds to an epitope located in the core region of lipopolysaccharide (LPS) of strain R20/Ol(-), we tested whether this epitope is shared and exposed by other species of the genus Klebsiella . The antibody was able to bind to LPS of clinical isolates of K. pneumonia e (n = 77), K. oxytoca (n = 50), K, terrigena (n = 49) and K. planticola (n = 50) in 93%, 98%, 96% and 100%, respectively, but did not bind to LPS of other Gram-negative genera (n = 159) as tested by Western blots and dot blo ts using proteinase K-digested whole cell lysates as antigens. Western blot analyses indicated that the antibody bound only to those LPS molecules whi ch did not carry an O-antigen and that the antibody is thus different from those already published.