Antigenic and physical diversity of Neisseria gonorrhoeae lipooligosaccharides

Abstract

We used mouse monoclonal antibodies (MAbs) to characterize Neisseria gonorrhoeae lipooligosaccharide (LOS). LOSs that bound two or more MAbs in a solid-phase radioimmunoassay usually bound them to different LOS components, as separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE); strains with multiple LOS components on SDS-PAGE usually bound more than one MAb. However, the LOS of some strains bound the same MAb to two LOS components with different relative molecular weights, and some individual LOS components bound more than one MAb. LOSs from different strains bound different amounts of the same MAb at saturation, reflecting differences in the quantitative expression of individual LOS components. Not all components recognized by MAbs were stained by silver after periodate oxidation. Treatment with NaOH variously affected epitopes defined by different MAbs. MAb 3F11 completely inhibited and MAb 2-1-L8 partially inhibited the binding of 125I-labeled 06B4 MAb to WR220 LOS and WR220 outer membranes in competitive binding studies. Other MAbs did not compete with the binding of '2'I-labeled 06B4 to either antigen. We conclude that a strain of N. gonorrhoeae elaborates multiple LOSs that can be separated by SDS-PAGE and that are antigenically distinct. Epitope expression within these glycolipids is complex. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) separates the principle outer membrane glycolipids, or lipooligosaccharides (LOSs), of Neisseria gonorrhoeae into multiple components with Mrs between 3,000 and 7,000, as determined with isogenic Salmonella rough mutant LOS standards (25, 26). High Mr components bearing polysaccharides composed of increasing numbers of oligosaccharide repeating units that are produced by smooth strains of members of the family Enterobacteriaceae (lipopolysaccharides [LPSs]) (7) are absent from gonococcal LOS. Gonococcal LOSs that migrate in the same molecular weight range as the bands observed with smooth enterobacterial LPS are LOS aggregates that diminish when treated with NaOH or when urea is included in the gel (16). For these reasons the term LOS has been used (8, 14, 24, 26, 33, 36) to distinguish the endotoxin moiety of Neisseria from the generally larger endotoxin molecules of members of the family Enterobacteriaceae. Antigen expression within gonococcal LOS is heterogeneous, reflecting the heterogeneity of molecular size (26). The complex antigenic structures of their LOSs have made serological classification of gonococci difficult and thwarted efforts to understand human immunity (1, 3, 5, 9, 16-18, 23, 24). Monoclonal antibodies potentially could provide ideal tools for defining the physical basis of antigen expression within complex glycolipids (6). Mouse monoclonal antibodies (MAbs) that bind to gonococcal LOSs have been described previously (2, 10, 14, 26). An immunoglobulin M (IgM) MAb, 3F11, recognizes a * Corresponding author. t This is report no. 2 from the Centre for Immunochemistry of the

Electrophoretic and Immunochemical Characterization of Lipopolysaccharide ofEdwardsiella ictalurifrom Channel Catfish

“…Lower-and medium-molecular-mass LPS bands were also more clearly seen in immunoblots of SDS-PAGE-resolved E. ictaluri LPS. Similar differences in visualization of LPS by silver staining and western blotting have been shown with the lipoligosaccharide from Neisseria gon-orrhoea (Mandrell et al 1986) and Serpulina (Treponema) hyodysenteriae (Halter and Joens 1988).…”

In vitro and in vivo modification of Neisseria gonorrhoeae lipooligosaccharide epitope structure by sialylation.

“…2), it is likely that it is associated with the lysis of serum-sensitive gonococci. It should be noted, however, that many serum-resistant strains also have the 4.5-kD component (and bind mAb 3F11) (10,11,14), indicating other, unidentified factors may be involved in the shift to serum resistance .…”

Conservation of the lipooligosaccharide synthesis locus lgt among strains of Neisseria gonorrhoeae: requirement for lgtE in synthesis of the 2C7 epitope and of the beta chain of strain 15253.

“…Blocking (1 h), mAb treatment (overnight), washes (15 rain three times), and second antibody treatment (3-4 h) were all carried out using a buffer consisting of 1% casein, 150 mM NaC1, 10 mM Tris (pH 7.5), and 30 mM NAN3. mAB 2C7 (18,19) was used at a dilution of 1:50. The second antibody was alkaline phosphatase-conjugated goat antibodies to mouse IgG, IgM, and IgA (Cappel, Organon Teknika Corp., West Chester, PA) used at a dilution of 1:2,000.…”