A monoclonal antibody recognizing the 3-deoxy-D-manno-oct-2-ulosonic acid (Kdo) trisaccharide alpha Kdo(2 -> 4)alpha Kdo(2 -> 4)alpha Kdo of Chlamydophila psittaci 6BC lipopolysaccharide

A monoclonal antibody (mAb) S45-18 was generated against a synthetic neogly coconjugate containing the trisaccharide alpha Kdo(2-->4)alpha Kdo (2-->4)a lpha Kdo (Kdo, 3-deoxy-D-manno-oct-2-ulopyranosonic acid) which represents a structure of the lipopolysaccharide (LPS) from Chlamydophila psittaci 6BC . The antibody was characterized by binding and inhibition assays in ELISA using: (i) the immunizing antigen and chemically synthesized derivatives th ereof; (ii) chlamydial elementary bodies (EB); and (iii) LPS of Chl, psitta ci 6BC and Chlamydia trachomatis L-2. The specificity was determined in com parison to that of mAb S25-23 recognizing the alpha Kdo(2-->8)alpha Kdo(2-- >4)alpha Kdo trisaccharide which represents an epitope shared by all specie s of the family. MAb S45-18 bound to an epitope of the structure alpha Kdo( 2-->4)alpha Kdo(2-->4)alpha Kdo, with lower reactivity with the (2-->8)-(2- ->4)-linked analog. Using chlamydial EB or LPS, mAb S45-18 bound preferenti ally to LPS and EB of Chi. psittaci. Therefore, Chi, psittaci LPS contains, in addition to the known genus-specific epitope, a species specific epitop e.