A recent study published in Nature Chemical Biology reveals that a laboratory-engineered antibody can effectively combat a typically fatal bacterial infection in mice. This innovative approach involves the antibody attaching to a unique bacterial sugar, thereby signaling the immune system to eliminate the harmful pathogen.
The research was co-led by Professor Richard Payne from the University of Sydney, alongside Professor Ethan Goddard Borger from WEHI and Associate Professor Nichollas Scott from the University of Melbourne and the Peter Doherty Institute for Infection and Immunity.
Professor Payne is also poised to direct the newly established Australian Research Council Centre of Excellence for Advanced Peptide and Protein Engineering. This center aims to leverage discoveries like this to accelerate the application of basic research in fields such as biotechnology, agriculture, and environmental conservation.
"This study illustrates the potential of integrating chemical synthesis with biochemistry, immunology, microbiology, and infection biology," stated Professor Payne. "By meticulously constructing these bacterial sugars using synthetic chemistry, we gained insights into their molecular structure, enabling us to create antibodies that bind with remarkable specificity. This advancement paves the way for innovative treatments for severe drug-resistant bacterial infections."
Why Targeting Bacterial Sugars is Innovative
The antibody developed targets a sugar molecule known as pseudaminic acid. While it shares similarities with sugars found in human cells, it is produced exclusively by bacteria. This unique characteristic makes it an ideal target, as many harmful pathogens utilize this sugar as a crucial component of their outer membrane, aiding their survival against immune responses.
As the human body does not generate this sugar, it provides a precise target for creating immunotherapies that spare healthy cells.
Creating a Versatile Antibody
To exploit this vulnerability, researchers synthesized the bacterial sugar and sugar-modified peptides from the ground up. This foundational work enabled them to ascertain the precise three-dimensional structure of the molecule and its configuration on bacterial surfaces.
Utilizing this intricate information, the team developed what they refer to as a "pan-specific" antibody, capable of recognizing the same sugar across various bacterial species and strains.
In studies involving infected mice, the antibody successfully eradicated multidrug-resistant Acinetobacter baumannii, a notorious cause of hospital-acquired pneumonia and bloodstream infections known for its treatment challenges.
"Multidrug-resistant Acinetobacter baumannii poses a significant threat in modern healthcare environments worldwide," remarked Professor Goddard-Borger. "It is not unusual for infections to resist even the most potent antibiotics. Our research serves as a compelling proof-of-concept that opens avenues for developing new, life-saving passive immunotherapies."
How Passive Immunotherapy Can Aid Patients
Passive immunotherapy involves administering pre-formed antibodies to promptly manage infections, rather than relying on the body's adaptive immune system to respond. This strategy can be employed for both treating active infections and preventing them.
In hospital environments, it could protect vulnerable patients in intensive care units who face high risks from drug-resistant bacteria.
Associate Professor Scott emphasized that these antibodies also provide a valuable new method for investigating bacterial disease mechanisms.
"These sugars play a pivotal role in bacterial virulence, yet they have been challenging to study," he noted. "Having antibodies that can selectively identify them allows us to map their presence and variations across different pathogens. This knowledge directly contributes to improved diagnostics and therapies."
Progressing Toward Clinical Application
Over the next five years, the research team aims to translate these findings into antibody treatments suitable for clinical use, focusing on multidrug-resistant A. baumannii. Achieving this objective would eliminate one of the most perilous members of the ESKAPE pathogens and represent a major advancement in the global fight against antimicrobial resistance.
"This is precisely the type of breakthrough the new ARC Centre of Excellence is designed to facilitate," Professor Payne concluded. "Our mission is to transform fundamental molecular insights into practical solutions that safeguard the most vulnerable individuals in our healthcare system."
The authors have declared no competing interests. Funding was provided by the National Health and Medical Research Council, Australian Research Council, National Institutes of Health, Walter and Eliza Hall Institute of Medical Research, and the Victorian State Government. The researchers acknowledge support from the Melbourne Mass Spectrometry and Proteomics Facility at the Bio21 Molecular Science and Biotechnology Institute.
All animal handling and procedures were conducted in compliance with the University of Melbourne guidelines and were approved by the University of Melbourne Animal Ethics Committee (application ID 29017).