Variable cross-reactivity of Pseudomonas aeruginosa lipopolysaccharide-core-specific monoclonal antibodies and its possible relationship with serotype

Abstract

The core region of Pseudomonas aeruginosa lipopolysaccharide (LPS) was analysed by four LPS-core-specific human monoclonal antibodies (mAbs; FK-2E7, MH-4H7,OM-lD6 and NM-3G8). Reactivity of these mAbs to about 180 P. aeruginosa strains was tested. FK-2E7 bound to strains of Homma serotype E and I at a frequency of about 90%, to strains of serotype M at about 50%, and to strains of serotype A and G at about 30%. MH-4H7 bound to P. aeruginosa strains of serotype A, F, G, H, K and M at a high frequency (45-87%), but did not bind to any strains of serotype B, C, E and I. OM-1D6 and NM-3G8 bound to P. aeruginosa strains in a nearly serotypespecific manner. OM-1D6 reacted with all strains of serotype G so far tested, and a few strains of serotype M.Furthermore, L-rhamnose in the LPS core of serotype G was an immunodominant sugar recognized by OM-1D6 as an epitope. NM-3G8 bound to only a few strains of serotype B and M. The variable reactivity of these mAbs suggests that antigenic heterogeneity of the LPS core is somewhat related with (O-polysaccharide-based) serotype. Among these mAbs, MH-4H7 and OM-1D6 showed a high level of protective activity against P.aeruginosa in an experimental infection model using normal mice. In vitto protective activity was shown to be closely related to in vitro binding activity to whole cells as determined by agglutination and flow cytometry, but not ELISA.

Identification of the lipopolysaccharide core region as the receptor site for a cytotoxin-converting phage, phi CTX, of Pseudomonas aeruginosa

“…The phenomenon also seemed to result from the structural diversity of the outer core of P. aeruginosa LPS. However, the host range showed 0-serotype dependency different from that of the anti-LPS core MAbs (43), suggesting that the LPS core structures recognized by the MAbs and 4CFX differed from each other and that each structure was distributed in a serotype-dependent manner among P. aeruginosa strains.…”

“…Previously, the heterogeneity of the LPS core of P. aeruginosa, determined by using human MAbs as probes, was reported (42,43). The outer core region was heterogeneous among P. aeruginosa strains in the properties of binding of a set of anti-LPS core MAbs, and the heterogeneity was serotype dependent.…”

“…Cell suspension (0.1 ml) was mixed with 0.9 ml of LB-Mg containing fCTX (3 x 104 PFU ml-') propagated on PAS10. (43). Briefly, the bacterial cells were boiled for 10 min in 10 mM Tris-HCl-10 mM MgCl2-2% Triton X-100 (pH 8.0).…”

“…The series of evidence described above indicated that a receptor site of OCTX was LPS and that the existence of a particular LPS core structure was essential for 4.CTX infection. In a recent study (43), the core structure of P.…”

“…Moreover, this heterogeneity correlated with 0 serotypes. Therefore, we examined the host range of 4CTX among the P. aeruginosa wild-type strains from various sources and its relationship to the 0 serotypes as well as to the binding activities of four anti-LPS core MAbs (43) and an anti-common polysac Genetic locus specifying 4CTX sensitivity. The results described above indicated that 4CTX might recognize a specific structure of the outer core distributed among strains of some particular 0 serotypes, suggesting that not only anti-core MAbs but also 4ICTX could be used as probes for studying the core structure of P. aeruginosa LPS, as shown for several bacteriophages in studies of the LPSs of enteric bacteria (32).…”