Investigation of the effect of anti-PIA/PNAG antibodies on biofilm formation in Escherichia coli

Polysaccharide Intercellular Adhesin (PIA), a surface polysaccharide produced by <i>Staphylococcus aureus</i> and <i>Staphylococcus epidermidis</i>, is a compelling target for opsonic and protective antibodies against these bacteria. <i>Escherichia coli</i> has recently made an exopolysaccharide called poly-<i>β</i>(1,6)-<i>N</i>-acetylglucosamine (PNAG), biochemically indistinguishable from PIA. This study investigated the effect of antibodies generated against PNAG on biofilm formation and the opsonization activity of secreted antibodies in <i>Escherichia coli</i>. Following purification and structural confirmation of PIA polysaccharide from producing <i>Staphylococcus epidermidis</i>, the ability to inhibit biofilm and the function of secreted antibodies for the mentioned polysaccharide were evaluated using semi-quantitative methods in a mouse model. Subsequently, the opsonic activity of antibodies targeting <i>Escherichia coli</i> strain ATCC 25922 was evaluated. The extracted polysaccharide was confirmed using FTIR, NMR, and colorimetric methods, and the results showed that the purified PIA induced protective antibodies with 40.48% opsonization properties in <i>E. coli</i>. The sera of the PIA-immunized groups showed a significant increase in antibody production and protective IgG titer levels compared to the control group. Also, the antibodies produced showed a substantial difference in inhibiting biofilm production <i>in vitro</i> compared to non-immunized serum. Antibodies directed against PIA with a lethality of 40.48% showed a significant effect on the absence of biofilm formation in <i>E. coli</i>. Despite the opsonic properties of the antibodies for <i>E. coli</i>, the simultaneous impact of these antibodies on infections caused by <i>S. epidermidis</i> and <i>E. coli</i> may have a role that requires further investigation and studies in animal models.