First Oral Salmonella Vaccine Tested in Mice

Salmonella remains one of the most common causes of foodborne illness across the world, however no vaccine exists to prevent against infection with the pathogen. Now, researchers at The University of Texas Medical Branch (UTMB) at Galveston, have developed an oral vaccine for salmonella poisoning.

The researchers originally developed injectable vaccines designed to be effective against three mutated versions of the Salmonella typhimurium bacteria. These studies showed that the experimental vaccines protected mice against a lethal dose of salmonella bacteria.

However, as oral vaccines are easier to administer, the researchers decided to reformulate their injectable preparations. The oral vaccine – the details of which were published in the journal, Frontiers in Cellular and Infection Microbiology – also follows the same digestive pathway as the salmonella bacteria.

“In the current study, we analyzed the immune responses of mice that received the vaccination by mouth as well as how they responded to a lethal dose of salmonella,” said Dr. Ashok Chopra, UTMB professor of microbiology and immunology. “We found that the orally administered vaccines produced strong immunity against salmonella, showing their potential for future use in people.”

Salmonella infections are commonly treated using antibiotics, however the emergence of antibiotic-resistant strains of the bacteria are a growing concern. Salmonella has also been used as a bioweapon; in 1984, a religious cult in rural Oregon contaminated local salad bars, leading to the poisoning of over 700 people.

In the US, about 1.4 million people are infected with salmonella each year, resulting in 15,000 hospitalizations due to salmonellosis and 400 deaths, according to statistics from the Centers for Disease Control and Prevention. While the total number of salmonella infections has stayed consistent since 1996, it’s estimated that for every one diagnosis, 39 infections go unreported.

This new oral salmonella vaccine could go a long way to reducing the 25 percent mortality rate associated with the infection. The vaccine is currently still being assessed in preclinical studies, and has yet to be tested in humans.