Engineered Gut Bacteria Form Protective Shield Against Dangerous Salmonella Infections in New Study
A team of researchers at Virginia Tech has successfully demonstrated a novel prophylactic approach to fighting dangerous intestinal infections, utilizing genetically modified bacteria to create a protective biological shield against pathogens like Salmonella. Published in the journal Nature Microbiology, the preclinical study highlights an innovative strategy that could eventually expand the medical toolkit available to combat drug-resistant bacterial strains without relying solely on traditional antibiotics.
The human gastrointestinal tract is home to a complex microbiome consisting of trillions of bacteria alongside natural viruses known as bacteriophages, or phages, which help regulate bacterial populations. Typically, each bacterial species maintains its own specific set of phage partners. When harmful, orally ingested pathogens enter this delicate ecosystem, they usually encounter an environment devoid of matching phages, allowing them to rapidly multiply and cause illness. By the time a host displays symptoms, introducing therapeutic phages is often too late, as the invaders have already established themselves and reached a stalemate with the existing microbiome.
To overcome this limitation, Associate Professor Bryan Hsu and lead author Rogerio A. Bataglioli, along with their colleagues, explored a preventive strategy. Rather than attempting to introduce external phages after an infection takes hold, the research team engineered a nonpathogenic strain of E. coli to act as a localized delivery system. This beneficial bacterium was modified to carry a specialized phage programmed to target and destroy Salmonella specifically. The researchers coined this novel phage-bacterial combination a “lyto-lysogen.”
“What happens is that this good bacteria, the E. coli, produces all this antipathogen phage, and there is now a protective lining so that when Salmonella comes in, just after passing through the stomach and at its weakest point, it meets this high, killer density of phages,” explained Hsu, an affiliate with the Fralin Life Sciences Institute’s Center for Emerging, Zoonotic, Arthropod-borne Pathogens.
One of the primary hurdles in utilizing bacteriophage therapy within the gut has been the body’s natural barriers and the tendency of phages and bacteria to coexist rather than engage in rapid eradication. Furthermore, pathogenic bacteria can often detect foreign phage DNA and prevent it from replicating. To trick the invading pathogens, the Virginia Tech researchers integrated a specific Salmonella gene into the genome of the modified E. coli. This genetic camouflage convinced the Salmonella bacteria that the incoming phage was not foreign, allowing the virus to infect the pathogen, multiply rapidly, and trigger a process called lysis that destroys the harmful bacteria.
The Virginia Tech team chose to focus their initial investigation on Salmonella due to its significant global disease burden. The pathogen poses severe risks to vulnerable populations, including young children, the elderly, and individuals with compromised immune systems. Additionally, rising rates of antibiotic resistance have prompted the Centers for Disease Control and Prevention to classify Salmonella as a high-priority pathogen.
While the current study successfully protected laboratory mice from oral Salmonella infections, the authors emphasize that this research represents an early step in a much broader scientific exploration. The underlying framework established by the team opens the door to adapting similar engineered bacterial systems to target other harmful enteric pathogens.
“We’re starting off with Salmonella, but expanding, obviously, with the correct adaptations to target other diseases; other bacterial pathogens, would be an interesting route to explore,” Bataglioli noted.
The investigators stress that this technology is not intended to replace standard antibiotics. Instead, the goal is to provide clinicians with an additional defensive option on the shelf to prevent and manage severe infections. Future developments will depend on adapting the methodology for other bacterial targets and eventually translating these promising laboratory findings into clinical applications for human health.
Funding and support for this research were provided by the National Institute of General Medical Sciences of the National Institutes of Health, alongside a Postdoctoral Fellowship in Drug Delivery from the PhRMA Foundation. Additional researchers contributing to the project included scientists from the Department of Biological Sciences, the Virginia-Maryland College of Veterinary Medicine, and academic institutions across the United States.
Source: News-Medical.net
