Extraction and Electrophoretic Analysis of Bacterial Lipopolysaccharides and Outer Membrane Proteins

Lipopolysaccharides (LPS) (or lipooligosaccharides [LOS], which lack the O-antigen side chains characteristic of LPS), and outer membrane proteins (OMP) are major cell-surface molecules in the outer membrane (OM) of gram-negative bacteria. The LPS is responsible for causing endotoxic shock in infected hosts and, in conjunction with some OMPs, provides protection to the bacterium against host innate immune defenses and attachment to host cells. Electrophoretic analysis can provide valuable information regarding the size, number, and variability of LPS/LOS and OMP components between bacterial strains and mutants, which aids in understanding the basic biology and virulence factors of a particular species. Furthermore, highly purified extracts are normally not required if only electrophoretic analysis is to be done, and various methods have been established for such procedures. Here, we review ameliorated procedures for fast and convenient extraction of LPS/LOS and protein-enriched outer membranes (PEOM) for optimal electrophoretic resolution. Specifically, we will describe the phenol-based micro-method for LPS/LOS extraction, a differential extraction procedure with sodium lauryl sarcosinate for PEOM, and gel preparation for electrophoretic analysis of LPS/LOS samples in detail. Graphic abstract: Workflow for the preparation and analysis of LPS/LOS and PEOM.

An update of Brachyspira hyodysenteriae serotyping

Brachyspira (B.) hyodysenteriae the causative agent of swine dysentery (SD) has been divided into 9 serotypes on basis of its lipooligosaccharide (LOS). Knowledge on circulating serotypes in Europe, however, is rare. Regarding that immunity to SD is serotype specific an update of B. hyodysenteriae serotyping was undertaken. A LOS band of 10 to 25kDa was identified being appropriate for this purpose. Isolates from Germany, Spain, Denmark, USA and Japan were characterized in the immunoblot by sera raised to serotypes 1 through 7, serogroups H and I (reference strains) and to eight German strains. In total, 57 (51%) isolates responded to at least one of the antisera. Regarding German isolates (n=75) only 35 (46.7%) were identified but mainly by antisera to German strains. Positive Spanish isolates (12 of 17) yielded similar results. In contrast, positively reacting Danish isolates (9 of 12) were mainly identified by antisera to the reference strains as it was the case for recent U.S. (1 of 8) and Japanese isolates (3 of 5). Results indicate that B. hyodysenteriae has a high degree of serological heterogeneity that has probably differently developed in diverse geographical areas over time. This situation represents a challenge for vaccine development.