The New Structure of Core Oligosaccharide Presented by Proteus penneri 40A and 41 Lipopolysaccharides

The new type of core oligosaccharide in Proteus penneri 40A and 41 lipopolysaccharides has been investigated by 1H and 13C NMR spectroscopy, electrospray ionization mass spectrometry and chemical methods. Core oligosaccharides of both strains were chosen for structural analysis based on the reactivity of LPSs with serum against P. penneri 40A core oligosaccharide–diphtheria toxoid conjugate. Structural analyses revealed that P. penneri 40A and 41 LPSs possess an identical core oligosaccharide

Interaction of Mannose-Binding Lectin With Lipopolysaccharide Outer Core Region and Its Biological Consequences

Lipopolysaccharide (LPS, endotoxin), the main surface antigen and virulence factor of Gram-negative bacteria, is composed of lipid A, core oligosaccharide, and O-specific polysaccharide (O-PS) regions. Each LPS region is capable of complement activation. We have demonstrated that LPS of Hafnia alvei, an opportunistic human pathogen, reacts strongly with human and murine mannose-binding lectins (MBLs). Moreover, MBL–LPS interactions were detected for the majority of other Gram-negative species investigated. H. alvei was used as a model pathogen to investigate the biological consequences of these interactions. The core oligosaccharide region of H. alvei LPS was identified as the main target for human and murine MBL, especially l-glycero-d-manno-heptose (Hep) and N-acetyl-d-glucosamine (GlcNAc) residues within the outer core region. MBL-binding motifs of LPS are accessible to MBL on the surface of bacterial cells and LPS aggregates. Generally, the accessibility of outer core structures for interaction with MBL is highest during the lag phase of bacterial growth. The LPS core oligosaccharide–MBL interactions led to complement activation and also induced an anaphylactoid shock in mice. Unlike Klebsiella pneumoniae O3 LPS, robust lectin pathway activation of H. alvei LPS in vivo was mainly the result of outer core recognition by MBL; involvement of the O-PS is not necessary for anaphylactoid shock induction. Our results contribute to a better understanding of MBL–LPS interaction and may support development of therapeutic strategies against sepsis based on complement inhibition

Table_1_Interaction of Mannose-Binding Lectin With Lipopolysaccharide Outer Core Region and Its Biological Consequences.pdf

<p>Lipopolysaccharide (LPS, endotoxin), the main surface antigen and virulence factor of Gram-negative bacteria, is composed of lipid A, core oligosaccharide, and O-specific polysaccharide (O-PS) regions. Each LPS region is capable of complement activation. We have demonstrated that LPS of Hafnia alvei, an opportunistic human pathogen, reacts strongly with human and murine mannose-binding lectins (MBLs). Moreover, MBL–LPS interactions were detected for the majority of other Gram-negative species investigated. H. alvei was used as a model pathogen to investigate the biological consequences of these interactions. The core oligosaccharide region of H. alvei LPS was identified as the main target for human and murine MBL, especially l-glycero-d-manno-heptose (Hep) and N-acetyl-d-glucosamine (GlcNAc) residues within the outer core region. MBL-binding motifs of LPS are accessible to MBL on the surface of bacterial cells and LPS aggregates. Generally, the accessibility of outer core structures for interaction with MBL is highest during the lag phase of bacterial growth. The LPS core oligosaccharide–MBL interactions led to complement activation and also induced an anaphylactoid shock in mice. Unlike Klebsiella pneumoniae O3 LPS, robust lectin pathway activation of H. alvei LPS in vivo was mainly the result of outer core recognition by MBL; involvement of the O-PS is not necessary for anaphylactoid shock induction. Our results contribute to a better understanding of MBL–LPS interaction and may support development of therapeutic strategies against sepsis based on complement inhibition.</p

The hybridization results of the 31 <i>Proteus</i> strains.

<p>The suspension arrays were divided into 3 groups: (A) O1, O2, O9, O17, O20, O21, O23ac, O30, O32 and O47; (B) O5, O6, O8, O11, O12, O27, O29a, O31ab and O45; (C) O3ab, O10, O13, O14ab, O18, O19a, O24, O33, O34, O36, O40 and O42; no cross reactions were observed for any probe tested in this study, and the Blank was a negative control; the x-axis represents the PCR products of different serotypes, the y-axis represents the MFI values, and the z-axis represents the specific probes used for detection.</p

The phylogenetic trees for <i>wzx</i> and <i>wzy</i> genes from the 60 <i>Proteus</i> serotypes.

<p>The <i>wzx</i> (A) and <i>wzy</i> (B) trees were constructed using <i>wzx</i> and <i>wzy</i> genes. The sequences were aligned using ClustalW v2.0, and the trees were constructed using the JC69 substitution model and the phyML v3.0.</p

Genetic diversity of the O antigens of <i>Proteus</i> species and the development of a suspension array for molecular serotyping

<div><p><i>Proteus</i> species are well-known opportunistic pathogens frequently associated with skin wound and urinary tract infections in humans and animals. O antigen diversity is important for bacteria to adapt to different hosts and environments, and has been used to identify serotypes of <i>Proteus</i> isolates. At present, 80 <i>Proteus</i> O-serotypes have been reported. Although the O antigen structures of most Proteus serotypes have been identified, the genetic features of these O antigens have not been well characterized. The O antigen gene clusters of <i>Proteus</i> species are located between the <i>cpxA</i> and <i>secB</i> genes. In this study, we identified 55 O antigen gene clusters of different <i>Proteus</i> serotypes. All clusters contain both the <i>wzx</i> and <i>wzy</i> genes and exhibit a high degree of heterogeneity. Potential functions of O antigen-related genes were proposed based on their similarity to genes in available databases. The O antigen gene clusters and structures were compared, and a number of glycosyltransferases were assigned to glycosidic linkages. In addition, an O serotype-specific suspension array was developed for detecting 31 <i>Proteus</i> serotypes frequently isolated from clinical specimens. To our knowledge, this is the first comprehensive report to describe the genetic features of <i>Proteus</i> O antigens and to develop a molecular technique to identify different <i>Proteus</i> serotypes.</p></div