Lipopolysaccharide-Specific but Not Anti-Flagellar Immunoglobulin A Monoclonal Antibodies Prevent Salmonella enterica Serotype Enteritidis Invasion and Replication within HEp-2 Cell Monolayers

The protective potential of immunoglobulin A (IgA) monoclonal antibodies (MAbs) directed against O and H antigens of Salmonella enterica serotype Enteritidis to prevent bacterial adhesion to and invasion of HEp-2 cells was evaluated. Although anti-flagellar IgA MAbs showed strong agglutinating capacities, they did not protect cell monolayers. In contrast, IgA MAbs specific for the O:9 epitope of Salmonella lipopolysaccharide antigen alone prevented S. enterica serotype Enteritidis entry and replication within HEp-2 cells, and the protection was not mediated by direct binding of antibodies to bacterial adhesins or by agglutination of microorganisms.