Evaluation of azoximer bromide (polyoxidonium) influence on the adhesive properties of the Yersinia pestis EV NIIEG vaccine strain by atomic force microscopy

Aim. To characterize the influence of azoximer bromide (polyoxidonium, PO) in cultivation conditions on the morpho- and nanomechanical cell surface properties of Y. pestis EV NIIEG vaccine strain and its derivatives Y. pestis КМ218 (pYT–, pYV–, pYP–), Y. pestis КМ216 (pYT–, pYV–, pYP+), Y. pseudotuberculosis, Y. enterocolitica by atomic force microsopy (AFM), as well as on the adhesion of cells Y. pestis EV NIIEG to human collagen type IV.Materials and methods. The measurements were carried out using the Solver P47-PRO probe microscope (NT-MDT, Russia), standard methods of semi-contact AFM and AFM imaging analysis program. The adhesion of Y. pestis EV NIIEG to type IV collagen was determined by the number of cells binding to glass slides covered with human collagen type IV.Results. The introduction of PO in the cultivation environment caused changes in the morphometric parameters of the cells of Y. pestis EV NIIEG vaccine strain and its isogenic derivatives (increase in volume, flatten ingested (S/H), index I (W/H). These changes were accompanied by the transformation of nanomechanical properties of the cell surface (reducing the root mean square, adhesion force), which countenance was associated with the plasmid profile. The lesser decrease of adhesion force in the absence of changes of the index I was observed in cells Y. pseudotuberculosis and Y. enterocolitica with plasmid pYV. In the strain Y. enterocolitica KM383 (pYV–) PO did not induce significant changes in the indicators studied. The introduction of the PO into the cultivation environment decreased the ability of Y. pestis EV cells to bind to human collagen type IV. Modification by PO the adhesive properties of the vaccine strain Y. pestis EV NIIEG was accompanied by an increase in its immunogenicity.