Discovery identifies potential new diagnostic biomarker for listeriosis an infection
WEST LAFAYETTE, Ind. – Purdue University doctoral scholar Dongqi Liu has recognized a beforehand unknown technique that the foodborne bacterium Listeria monocytogenes makes use of to invade and infect people and animals.
“Listeria is a large downside within the meals trade and for individuals who get contaminated,” mentioned Arun Bhunia, a meals microbiology professor within the Department of Food Science at Purdue. L. monocytogenes infects an estimated 1,600 annually within the U.S., leading to about 260 deaths. At highest danger are pregnant ladies, unborn fetuses, immune-compromised and aged individuals.
“It’s taking place from several types of ready-to-eat meals,” Bhunia mentioned, together with contemporary produce, fruit, cheese, scorching canines and sliced meat. “A few of your favourite meals may very well be a significant downside.” And the one prevention is to avoid eating certain types of food.
After tainted meals is consumed, the bacterium causes listeriosis by passing by means of the abdomen and the gut, then spreading into the liver, spleen and even the mind. Bhunia’s earlier analysis has proven that the Listeria adhesion protein (LAP) performs an essential position in serving to L. monocytogenes to go by means of the intestine barrier.
However a query lingered concerning the LAP. After the pathogen secretes LAP, the protein stays on the bacterium’s floor. The way it does so remained a thriller. LAP should keep fixed to the bacterial floor for Listeria to trigger an infection.
“If the bacterium has no manner of protecting that protein on the floor, it actually has no perform,” Bhunia mentioned. “It’s not serving to the bacterium to work together with the intestinal cells.”
Dongqi Liu, who not too long ago accomplished his doctorate in meals science at Purdue College, examines mouse tissue that has been contaminated with the foodborne pathogen Listeria monocytogenes. (Purdue College Agricultural Communications photograph/Tom Campbell)
Download image
Now Liu, a Bilsland Dissertation Fellow who works in Bhunia’s laboratory, has answered this query. Liu has proven that the pathogen makes use of a sticky virulence protein referred to as internalin B to anchor LAP to bacterial surfaces.
Liu, Bhunia and 16 collaborators from Purdue College and Germany’s Technical College of Braunschweig published the details within the journal Cell Reviews. The work in Purdue’s Middle for Meals Security Engineering was funded by the U.S. Department of Agriculture’s Agricultural Research Service and the National Institute of Food and Agriculture.
A greater understanding of Listeria might result in simpler prevention. Virulence proteins are signature molecules which might be extra generally present in a particular location on the Listeria chromosome referred to as “the pathogenic island.”
Arun Bhunia, professor of meals microbiology at Purdue College, shows colonies (the black specks) of the foodborne pathogen Listeria monocytogenes. (Purdue College Agricultural Communications photograph/Tom Campbell)
Download image
The virulence proteins of that area all carry a novel amino acid sequence tag that may be utilized to foretell its virulent conduct and mechanisms, together with how it’s secreted and the way it’s anchored on the bacterial floor.
LAP could have managed to stay missed in listeriosis till now as a result of it doesn’t belong in that chromosomal area, and scientists have restricted data on how LAP remained connected to the bacterial floor in inflicting host an infection.
Now scientists know that internalin B turns LAP right into a moonlighting pathogenic issue by attaching it to a cell’s floor in Listeria. The cooperation of every protein is important for pathogenesis.
Liu and his colleagues used a battery of subtle biochemical strategies, together with fiber-optic sensors, immunoprecipitation, and mass spectrometry, to seek out the ligand that fastens LAP to mobile surfaces.
“We name it ligand fishing,” Bhunia mentioned. “We had a fishing expedition.”
LAP is just one fish in an enormous biochemical sea, however Listeria associates with different proteins that may assist them infect their host organisms.
“LAP is a housekeeping enzyme, so the virulence regulation and the pathogenesis are a bit totally different than different conventional virulence elements,” Lui mentioned.
It’s an alternate technique of the pathogens.
“If one is dropped, they wish to survive and they also use one other technique to trigger an infection,” Bhunia mentioned. Understanding this technique raises the prospect of stopping future listeriosis outbreaks. Additional analysis may reveal tips on how to create circumstances that stop the bacterium or the protein from staying on the floor.
“It is a difficult course of. There isn’t any single, straightforward resolution,” Bhunia cautioned.
This isn’t a novel scenario for Listeria, as proteins secreted and displayed on the floor like LAP are additionally present in different pathogenic micro organism, equivalent to Streptococcus pyogenes and Mycobacterium tuberculosis. LAP is the primary of its sort that the floor anchoring mechanism has characterised.
“The pathogens often secrete giant portions of those enzymes throughout an infection, which is instantly related to bacterial virulence,” Liu mentioned. “These proteins or their corresponding antibodies within the host could be an important diagnostic and prognostic marker for infectious ailments.”
A number of critical listeriosis outbreaks motivated Bhunia to start learning the illness about 25 years in the past. Early on, his workforce recognized LAP. Later, he realized that LAP binds to a receptor on epithelial cells to permit the bacterium to go by means of the intestine barrier. This different intestinal crossing technique of Listeria is acknowledged and was revealed in 2018 in Cell Host & Microbe.
The brand new discovering might assist Bhunia and others develop an antibody complement or vaccine to forestall listeriosis in inclined populations, particularly pregnant ladies. Bhunia has patented a bioengineered probiotic that would probably stop infections. Ladies who’ve skilled listeriosis-related being pregnant problems sometimes contact Bhunia for assist.
“These experiences develop into very private,” he mentioned. “If you work on Listeria, you all the time consider the individuals you are attempting to assist.”
Author: Steve Koppes
Media contact: Maureen Manier, mmanier@purdue.edu
Sources: Arun Bhunia, bhunia@purdue.edu; Dongqi Liu, liu1792@purdue.edu
Agricultural Communications: 765-494-8415;
Maureen Manier, Division Head, mmanier@purdue.edu
