US scientists develop new vaccine for swine

Ames, Iowa – Scientists with the US Department of Agriculture’s Agricultural Research Service (ARS) have developed a new vaccine for pigs.

In a report on the USDA’s website (“New Vaccine Fights Multiple Salmonella Types,” by Sandra Avant) the ARS explains that some types of Salmonella cause disease in food animals and others cause disease in humans. The new vaccine can protect pigs from both of those types.

Currently Salmonella vaccines available in the US protect against one type of the pathogen. It’s also “easiest to make a vaccine for a single type of Salmonella, but this can leave pigs vulnerable to other types that may infect them as well,” says the report.

Shawn Bearson, a microbiologist in ARS’s Food Safety and Enteric Pathogens Research Unit in Ames, Iowa, says that’s the challenge. “But another challenge is that the vaccines need to reduce Salmonella types that don’t cause disease in pigs but do cause foodborne disease in humans. Those are called ‘commensal’ organisms,” says Bearson in the report.

Commensal Salmonella, explains the report, lives in the gastrointestinal tract of food animals without making them sick. However, “when the animal goes to market or its manure is used to fertilize food crops that are not cooked before they are eaten, the bacterium then poses a foodborne risk to humans.”

Bearson, along with Brad Bearson, together created a new vaccine that protects both the food animals against commensal and disease-causing types of Salmonella.

The report adds that their “experiments showed that the new vaccine was effective against two types of Salmonella, Typhimurium and Choleraesuis, in pigs. It also protected turkeys against Typhimurium and a multidrug-resistant Salmonella type, Heidelberg.”

“Typhimurium is one of the most prevalent causes of food poisoning in humans,” explains Brad Bearson in the report. “It’s also a common commensal in pigs, poultry, and cattle.”

The two scientists say the vaccine has been tested against only three types of Salmonella, but it may protect against many other types of Salmonella in different food animals, says the report.