The Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD, USA
There is no licensed vaccine for the prevention of shigellosis. Our approach to the development of a Shigella vaccines is based on inducing serum IgG antibodies to the O-specific polysaccharide (O-SP) domain of their lipopolysaccharides (LPS). We have shown that low molecular mass O-SP-core (O-SPC) fragments isolated from Shigella sonnei LPS conjugated to proteins induced significantly higher antibody levels in mice than the full length O-SP conjugates. This finding is now extended to the O-SPC of Shigella flexneri 2a and 6, and Shigella dysenteriae type 1. The structures of O-SPC, containing core plus 1-4 O-SP repeat units (RUs), were analyzed by NMR and mass spectroscopy. The first RUs attached to the cores of S. flexneri 2a and 6 LPS were different from the following RUs in their O-acetylation and/or glucosylation. Conjugates of core plus more than 1 RU were necessary to induce LPS antibodies in mice. The resulting antibody levels were comparable to those induced by the full length O-SP conjugates. In S. dysenteriae type 1, the first RU was identical to the following RUs, with the exception that the GlcNAc was bound to the core in the β-configuration, while in all other RUs the GlcNAc was present in the α-configuration. In spite of this difference, conjugates of S. dysenteriae type 1 core with 1, 2, or 3 RUs induced LPS antibodies in mice with levels statistically higher than those of the full size O-SP conjugates. O-SPC conjugates are easy to prepare, characterize, and standardize, and their clinical evaluation is planned.
13C NMR, 1H NMR, methylation, SDS-PAGE, sugar analysis, MALDI-TOF MS, NMR-1D, serological methods, statistical analysis, immunization, conjugation
13C NMR data:
Linkage Residue C1 C2 C3 C4 C5 C6
5,3,3,3,2,2 aDGalp 97.1 69.5 70.6 71.0 72.5 62.5
5,3,3,3,2 aDGalp 93.7 73.5 69.0 70.5 72.4 62.4
5,3,3,3,4,6,3,2,3 aDRhap 103.5 71.4 71.4 73.3 70.3 17.8
5,3,3,3,4,6,3,2 aDRhap 102.8 70.8 79.2 72.6 70.5 17.8
5,3,3,3,4,6,3 aDGalp 98.7 75.0 70.1 70.5 72.2 61.8
5,3,3,3,4,6,2 Ac
5,3,3,3,4,6 bDGlcpN 102.2 55.3 78.4 72.6 77.0 61.7
5,3,3,3,4 bDGalp 104.3 72.1 73.6 69.3 74.0 68.5
5,3,3,3 aDGlcp 96.1 75.1 71.2 79.3 71.3 60.9
5,3,3 aDGlcp 102.6 71.4 77.8 71.5 73.6 61.0
5,3,4 P
5,3,7 aXLDmanHepp
5,3 aXLDmanHepp
5,4 P
5 aXLDmanHepp
?XKdo?
1H NMR data:
Linkage Residue H1 H2 H3 H4 H5 H6
5,3,3,3,2,2 aDGalp 5.27 3.86 3.97 4.02 4.17 3.76-3.77
5,3,3,3,2 aDGalp 5.58 4.02 4.12 4.07 4.10 3.77-3.77
5,3,3,3,4,6,3,2,3 aDRhap 5.08 4.07 3.85 3.47 3.85 1.32
5,3,3,3,4,6,3,2 aDRhap 5.06 4.17 3.87 3.56 3.88 1.32
5,3,3,3,4,6,3 aDGalp 5.60 3.95 3.93 4.10 3.90 3.77-3.77
5,3,3,3,4,6,2 Ac
5,3,3,3,4,6 bDGlcpN 4.65 3.84 3.84 3.71 3.49 3.77-3.93
5,3,3,3,4 bDGalp 4.47 3.56 3.65 3.91 3.81 3.89-3.96
5,3,3,3 aDGlcp 5.76 3.78 4.03 3.73 4.18 3.88-4.01
5,3,3 aDGlcp 5.21 3.68 4.08 3.77 3.92 3.82-3.89
5,3,4 P
5,3,7 aXLDmanHepp
5,3 aXLDmanHepp
5,4 P
5 aXLDmanHepp
?XKdo?
1H/13C HSQC data:
Linkage Residue C1/H1 C2/H2 C3/H3 C4/H4 C5/H5 C6/H6
5,3,3,3,2,2 aDGalp 97.1/5.27 69.5/3.86 70.6/3.97 71.0/4.02 72.5/4.17 62.5/3.76-3.77
5,3,3,3,2 aDGalp 93.7/5.58 73.5/4.02 69.0/4.12 70.5/4.07 72.4/4.10 62.4/3.77-3.77
5,3,3,3,4,6,3,2,3 aDRhap 103.5/5.08 71.4/4.07 71.4/3.85 73.3/3.47 70.3/3.85 17.8/1.32
5,3,3,3,4,6,3,2 aDRhap 102.8/5.06 70.8/4.17 79.2/3.87 72.6/3.56 70.5/3.88 17.8/1.32
5,3,3,3,4,6,3 aDGalp 98.7/5.60 75.0/3.95 70.1/3.93 70.5/4.10 72.2/3.90 61.8/3.77-3.77
5,3,3,3,4,6,2 Ac
5,3,3,3,4,6 bDGlcpN 102.2/4.65 55.3/3.84 78.4/3.84 72.6/3.71 77.0/3.49 61.7/3.77-3.93
5,3,3,3,4 bDGalp 104.3/4.47 72.1/3.56 73.6/3.65 69.3/3.91 74.0/3.81 68.5/3.89-3.96
5,3,3,3 aDGlcp 96.1/5.76 75.1/3.78 71.2/4.03 79.3/3.73 71.3/4.18 60.9/3.88-4.01
5,3,3 aDGlcp 102.6/5.21 71.4/3.68 77.8/4.08 71.5/3.77 73.6/3.92 61.0/3.82-3.89
5,3,4 P
5,3,7 aXLDmanHepp
5,3 aXLDmanHepp
5,4 P
5 aXLDmanHepp
?XKdo?