The study – published in PLoS ONE – reports that the use of a recombinant probiotic containing adhesion proteins found in the Listeria monocytogenes could be used as a method to reduce infection with L. monocytogenes in high-risk populations.
Professor Arun Bhunia, of Purdue University, USA, revealed that genetically engineering the same proteins that allow Listeria to pass through intestinal cells and into bloodstreams into a probiotic can help to block the pathways – thus reducing the risk of infection.
"Based on the research, it looks very promising that we would get a significant reduction in Listeria infections," said Bhunia.
"It's creating a competition. If Listeria comes in, it doesn't find a place to attach or invade."
The research team noted that the potential benefits of a recombinant probiotic would be two-fold – by directly acting as an antimicrobial agent against the target pathogen, but also by indirect offering general health benefits that the consumption of probiotics may bring.
However it remains to be seen whether such a modified probiotic bacteria would be approved for use in foods or supplements by regulatory bodies.
Listeria is a foodborne pathogen that infects at risk people through consumption of contaminated food – causing a severe systemic infection known as listeriosis.
The bacteria pose a significant health risk to pregnant women, newborns, the elderly, and other immunocompromised individuals.
In the gut, the Listeria bacteria enter the bloodstream by using adhesion proteins (LAP) to help them pass through the gut lining.
Bhunia and his colleagues explained that a recombinant probiotic expressing LAP could help to block Listeria from crossing the gut lining, thus promoting clearance and offering protection to high-risk populations.
The research team investigated whether probiotic bacteria or LAP-expressing recombinant probiotics (Lactobacillus paracasei) were able to prevent infection by blocking adhesion and invasion of L. monocytogenes in culture of gut lining cells.
The team reported that whilst several ‘wild type’ probiotic bacteria showed strong adhesion to gut lining cells, none were able to effectively prevent L. monocytogenes infection.
However, they noted that exposure to an LAP-expressing recombinant probiotic between one and 24 hours before exposure to Listeria significantly reduced adhesion, invasion, and trans-epithelial translocation of the infectious bacteria.
“Pre-exposure reduced L. monocytogenes translocation by as much as 46% after 24 hours,” explained the researchers.
They also noted that the modified probiotic prevented Listeria mediated cell damage by more than 99% after one hour and 79% after 24 hours.
“These data show promise for the use of recombinant probiotics in preventing L. Monocytogenes infection in high-risk populations,” concluded Bhunia and his team.
Source: PLoS ONE
Published online ahead of print, doi: 10.1371/journal.pone.0029277
“Recombinant Probiotic Expressing Listeria Adhesion Protein Attenuates Listeria monocytogenes Virulence In Vitro”
Authors: O.K. Koo, M.A.R. Amalaradjou, A.K. Bhunia