Development of Opsonic Mouse Monoclonal Antibodies against Multidrug-Resistant Enterococci.
Multidrug-resistant enterococci are major causes of hospital-acquired infections. Immunotherapy with monoclonal antibodies (MAbs) targeting bacterial antigens would be a valuable treatment option in this setting. Here, we describe the development of two MAbs through hybridoma technology that target antigens from the most clinically relevant enterococcal species. Diheteroglycan (DHG), a well-characterized capsular polysaccharide of Enterococcus faecalis, and the secreted antigen A (SagA), an immunogenic protein from Enterococcus faecium, are both immunogens that have been proven to raise opsonic and cross-reactive antibodies against enterococcal strains. For this purpose, a conjugated form of the native DHG with SagA was used to raise the antibodies in mice, while enzyme-linked immunosorbent assay and opsonophagocytic assay were combined in the selection process of hybridoma cells producing immunoreactive and opsonic antibodies targeting the selected antigens. From this process, two highly specific IgG1(κ) MAbs were obtained, one against the polysaccharide (DHG.01) and one against the protein (SagA.01). Both MAbs exhibited good opsonic killing against the target bacterial strains: DHG.01 showed 90% killing against E. faecalis type 2, and SagA.01 showed 40% killing against E. faecium 11231/6. In addition, both MAbs showed cross-reactivity toward other E. faecalis and E. faecium strains. The sequences from the variable regions of the heavy and light chains were reconstructed in expression vectors, and the activity of the MAbs upon expression in eukaryotic cells was confirmed with the same immunological assays. In summary, we identified two opsonic MAbs against enterococci which could be used for therapeutic or prophylactic approaches against enterococcal infections.
['Kalfopoulou|Ermioni|E|0000-0002-4125-5101', 'Laverde|Diana|D|', 'Miklic|Karmela|K|', 'Romero-Saavedra|Felipe|F|', 'Malic|Suzana|S|', 'Carboni|Filippo|F|', 'Adamo|Roberto|R|', 'Lenac Rovis|Tihana|T|', 'Jonjic|Stipan|S|', 'Huebner|Johannes|J|']
D000818:Animals D000911:Antibodies, Monoclonal D000942:Antigens, Bacterial D016667:Bacterial Capsules D004352:Drug Resistance, Microbial D013293:Enterococcus faecalis D016984:Enterococcus faecium D007167:Immunotherapy D051379:Mice D009895:Opsonin Proteins D011134:Polysaccharides
opsonic monoclonal antibodies hybridoma technology diheteroglycan DHG capsular polysaccharide Enterococcus faecalis SagA Enterococcus faecium opsonophagocytic assay