Danish scientists are working on developing a phage preparation to prevent diarrhea caused by enterotoxigenic E. coli in pigs.

Denmark is a country whose economy has traditionally relied heavily on pig farming. Pork is not only a favorite staple in Danish cuisine but also one of the country's key exports. It's no surprise that the search for ways to improve the profitability of this industry is ongoing.

One of the main problems in Danish pig farming is diarrhea, which occurs in piglets during the post-weaning period (after weaning), and is most often caused by enterotoxigenic E. coli (ETEC). When ETEC enters the intestine, it begins to secrete a toxin that causes severe diarrhea. Zinc oxide is used to limit the spread of ETEC, but this compound has several drawbacks: its use is associated with the transfer of antibiotic resistance genes and has a negative impact on the environment. Therefore, ETEC will be banned for use in pig farming in Europe from 2022. What other ways are there to prevent ETEC infection in pigs?

Scientists from the PHAGEBio group, which researches bacteriophage biology at the University of Copenhagen, decided to test the bacteria's natural enemies—bacteriophages—against ETEC. It turned out that defeating ETEC this way was not easy: E. coli demonstrated resistance to previously isolated phages specific to E. coli . They had to collect and test over 2,000 new phage-enriched samples to identify phages that would destroy ETEC. Many such phages were found, but sequencing their genomes revealed that 90% of them were temperate, meaning they could persist in the bacterial genome for a long time in a "dormant" state without destroying it (a state known as lysogeny).

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Scientists haven't stopped their search, having acquired a wealth of new data on phage biology and the mechanisms of their interactions with bacterial hosts. They are currently working on creating a phage cocktail that would specifically destroy ETEC and are simultaneously developing a technology for delivering phages as solid feed additives. These additives will have a preventative effect and will be safe, inexpensive, and easy to use. They could replace zinc oxide in pig farming, thereby increasing productivity, improving animal health, reducing antibiotic use, and reducing the spread of antibiotic resistance in livestock production.