SummaryThere is a strong association between Guillain-Barr~ syndrome (GBS) and Penner's serotype 19 (PEN 19) of CamFflobacterjejuni. Sera from patients with GBS after C. jejuni infection have autoantibodies to GM1 ganglioside in the acute phase of the illness. Our previous work has suggested that GBS results from an immune response to cross-reactive antigen between lipopolysaccharide (LPS) of the Gram-negative bacterium and membrane components of peripheral nerves. To clarify the pathogenesis of GBS, we have investigated whether GMl-oligosaccharide structure is present in the LPS of C. jejuni (PEN 19) that was isolated from a GBS patient. After extraction of the LPS, the LPS showing the binding activity of cholera toxin, that specifically recognizes the GMl-oligosaccharide was purified by a silica bead column chromatography. Gasliquid chromatography-mass spectrometric analysis has shown that the purified LPS contained Gal, GalNAc, and NeuAc, which are sugar components of GM1 ganglioside. 1H NMR methods [Carr-Purcell-Meiboom-Gill (CPMG), total correlation spectroscopy (TOCSY), and nuclear Overhauser effect spectroscopy (NOESY)] have revealed that the oligosaccharide structure [GalB1-3GalNAcB1-4(NenAcot2-3)GalB] protrude from the LPS core. This terminal structure [GalB1-3GalNAcB1-4(NeuAcot2-3)GalB] is identical to the terminal tetrasaccharide of the GM1 ganglioside. This is the first study to demonstrate the existence of molecular mimicry between nerve tissue and the infectious agent that elicits GBS.

Developmental changes in ganglioside composition and biosynthesis was studied in rat brain between embryonic day (E) 14 and birth. In E14 brains, GM3 and GD3 were predominant. At E16, "b" series gangliosides, such as GD1b, GT1b, and GQ1b, increased in content. After E18, "a" series gangliosides such as GM1, GD1a, and GT1a increased in content, and the content of GM3 and GD3 markedly decreased. Because of these changes in composition, we determined the activities, in homogenates of embryonic brains, of two key enzymes of ganglioside synthesis: sialyltransferase for the synthesis of GD3 from GM3 and N-acetylgalactosaminyltransferase for GM2 synthesis from GM3. The sialyltransferase activity (GM3----GD3) was constant between E14 and E18 but decreased rapidly from E18 to birth. In contrast, the N-acetylgalactosaminyltransferase activity (GM3----GM2) increased between E14 and E18 but was constant from E18 to birth. These changes in ganglioside composition and enzymatic activities indicate that during development there is a shift from synthesis of the simplest gangliosides of the "a" and "b" pathways to synthesis of the more complex gangliosides.

Influenza is an infectious disease caused by the influenza virus, and each year many people suffer from this disease. Hemagglutinin (HA) in the membrane of type A influenza viruses recognizes sialylglycoconjugate receptors on the host cell surface at an initial step in the infection process; consequently, HA inhibitors are considered potential candidates for antiviral drugs. We identified peptides that bind to receptor-binding sites through a multiple serial selection from phage-displayed random peptide libraries. Using the HA of the H1 and H3 strains as target proteins, we obtained peptides that bind to both HAs. The binding affinities of peptides for these HAs were improved by secondary and tertiary selections from the corresponding sublibraries. A docking simulation suggested that, similar to sialic acid, the peptides are recognized by the receptor-binding site in HA, which indicates that these peptides mimic the sialic acid structure. N-stearoyl peptides inhibited infections by the A/Puerto Rico/8/34 (H1N1) and A/Aichi/2/68 (H3N2) strains of influenza virus. Such HA-inhibitors are promising candidates for novel antiviral drugs.

We isolated Campylobacter jejuni from 2 patients with Fisher's syndrome subsequent to enteritis. Crude lipopolysaccharide fractions were extracted from the bacteria and separated by thin-layer chromatography. Monoclonal antibodies to GQ1b ganglioside (GMR13 and 7F5) reacted with both lipopolysaccharide fractions, indicating that the lipopolysaccharides bear the GQ1b epitope. This is the first report of molecular mimicry between neural tissue components and the antecedent infectious agents of Fisher's syndrome.

Ganglioside GalL L1C C3GalNAcL L1C C4(NeuAcK K2C C3) GalL L1C C4GlcL L1C C1'Cer (GM1)-binding peptides were obtained from a phage-displayed pentadecapeptide library by an affinity selection. The selection processes were in situ-monitored by a quartz-crystal microbalance method, on which a ganglioside GM1 monolayer was transferred. After five rounds of biopanning, the DNA sequencing of 18 selected phages showed that only three individual clones were selected. The peptide sequences of the random region were found to be DFRRLPGAFWQLRQP, GWWYKGRARPVSAVA and VWRLLAPPFSNRLLP. Binding constants of these phage clones to the GM1 monolayer were 10 10 M 31 . Three synthetic pentadecapeptides inhibited the binding of cholera toxin B subunit to the GM1 monolayer with an IC 50 of 24, 13 and 1.0 W WM, respectively. These peptides will be useful for searching functional roles of ganglioside GM1.z 1999 Federation of European Biochemical Societies.