Force spectroscopy of interactions between Yersinia pseudotuberculosis and Yersinia pestis cells and monoclonal antibodies using optical tweezers.

The interactions of a microbial cell with host cells and humoral factors play an important role in the development of infectious diseases. The study of these mechanisms contributes to the development of effective methods for the treatment of bacterial infections. One of the possible approaches to studying bacterial adhesion to host cells is based on the use of the optical trap method. The aim of this work was to assess the significance of lipopolysaccharide O-antigen on the adhesiveness of Yersinia pseudotuberculosis using a model system including a bacterial cell captured by a laser beam and monoclonal antibodies (mAbs) bound covalently to a glass substrate. Registered interaction forces between Y. pseudotuberculosis cells and complementary antibodies to the O-antigen of lipopolysaccharide (LPS) or the B antigen outer membrane protein were 5.9 ± 3.3 and 2.0 ± 1.8 pN, respectively. Interaction forces between O-antigen deficient Y. pestis cells and the mentioned mAbs were 4.2 ± 2.9 and 9.6 ± 4.9 pN. The results are qualitatively consistent with earlier data obtained by using a model system based on polymer beads sensitized with LPS from Y. pseudotuberculosis and Y. pestis and surfaces coated by the aforementioned antibodies. This indicates that the immunochemical activity of Y. pseudotuberculosis cells is mediated mainly by the lipopolysaccharide. The model described can be used in similar studies of physicochemical and immunochemical mechanisms of bacterial adhesiveness.