Anti-MrkA Monoclonal Antibodies Reveal Distinct Structural and Antigenic Features of MrkA
Qun Wang1, Yan Chen2, Romana Cvitkovic1
1Dept. of Infectious Disease and Vaccines, MedImmune, Gaithersburg, MD, United States of America.
Abstract:
Antibody therapy against antibiotics resistant Klebsiella pneumoniae infections represents a promising strategy, the success of which depends critically on the ability to identify appropriate antibody targets. Using a target-agnostic strategy, we recently discovered MrkA as a potential antibody target and vaccine antigen. Interestingly, the anti-MrkA monoclonal antibodies isolated through phage display and hybridoma platforms all recognize an overlapping epitope, which opens up important questions including whether monoclonal antibodies targeting different MrkA epitopes can be generated and if they possess different protective profiles. In this study we generated four anti-MrkA antibodies targeting different epitopes through phage library panning against recombinant MrkA protein. These anti-MrkA antibodies elicited strong in vitro and in vivo protections against a multi-drug resistant Klebsiella pneumoniae strain. Furthermore, mutational and epitope analysis suggest that the two cysteine residues may play essential roles in maintaining a MrkA structure that is highly compacted and exposes limited antibody binding/neutralizing epitopes. These results suggest the need for further in-depth understandings of the structure of MrkA, the role of MrkA in the pathogenesis of Klebsiella pneumoniae and the protective mechanism adopted by anti-MrkA antibodies to fully explore the potential of MrkA as an efficient therapeutic target and vaccine antigen.
Insights
New antibodies targeting Klebsiella pneumoniae show promise for treating antibiotic-resistant infections. Researchers identified MrkA as a key target, developing antibodies that offer protection against multi-drug resistant strains.
Area of Science:
- Microbiology
- Immunology
- Infectious Diseases
Background:
- Antibiotic resistance in Klebsiella pneumoniae poses a significant global health threat.
- Antibody-based therapies are a promising strategy to combat resistant bacterial infections.
- Identifying effective antibody targets is crucial for developing successful therapeutic interventions.
Purpose of the Study:
- To generate and characterize novel anti-MrkA monoclonal antibodies targeting distinct epitopes.
- To evaluate the protective efficacy of these antibodies against multi-drug resistant Klebsiella pneumoniae.
- To investigate the structural role of cysteine residues in MrkA's antigenicity and antibody binding.
Main Methods:
- Phage library panning against recombinant MrkA protein to isolate specific antibodies.
- In vitro and in vivo assays to assess antibody-mediated protection against Klebsiella pneumoniae.
- Epitope mapping and mutational analysis to understand antibody-target interactions and protein structure.
Main Results:
- Four distinct anti-MrkA monoclonal antibodies were successfully generated, recognizing different epitopes.
- These antibodies demonstrated significant in vitro and in vivo protective effects against a multi-drug resistant Klebsiella pneumoniae strain.
- Analysis indicated that two cysteine residues are critical for maintaining MrkA's compact structure and limiting epitope accessibility.
Conclusions:
- MrkA is a viable target for antibody-based therapies and vaccine development against Klebsiella pneumoniae.
- Targeting diverse MrkA epitopes may offer varied protective mechanisms and overcome potential resistance.
- Further structural and mechanistic studies are needed to fully harness MrkA's therapeutic potential.
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