A vaccine against Salmonella may be one step closer, according to a research team led by a University of California, Davis immunologist.

In a study to be published this week in the early edition of the Proceedings of the National Academy of Sciences, the researchers say they have paved the way toward an effective vaccine by identifying eight antigens — molecules in the invading bacteria that trigger an immune response — common in mice and human infections.

“These antigens will provide the research community with a foundation for developing a protective salmonella vaccine,” said Stephen McSorley, an immunologist and associate professor in the UC Davis Center for Comparative Medicine, in a news release.

Every year, about 40,000 cases of salmonellosis are confirmed in the U.S., according to the Centers for Disease Control and Prevention, but because most cases not diagnosed and therefore not reported, the actual number of infections may be 1.2 million or more.

Children, younger than five, are the most likely to get salmonellosis. About 400 people perish each year because of acute infections.

In working toward a vaccine, the UC Davis-led research team said it created an array, or collection, of 2,700 proteins — about 60 percent of all proteins produced by Salmonella bacteria. The researchers found that 117 of those proteins behaved as antigens when mixed with blood serum from Salmonella-infected mice, triggering an immune response to defend against the bacteria. Fourteen of those proteins were common to all four strains of mice involved in the study.

The researchers also identified 14 proteins that served as antigens in the blood serum from Malawian children infected with Salmonella. Eight of those 14 proteins, or 57 percent, were among the 117 antigens identified in the mice.

McSorley said discovery of the eight antigens in both mouse and human infections suggests that some of these antigens might be used in developing a vaccine to protect against Salmonella, and that the mouse model of Salmonella would be useful before the research moves into clinical trials.

Collaborating on the project, which was funded by The National Institutes of Health; the Wellcome Trust and the pharmaceutical company GlaxoSmithKline, were UC Irvine; the University of Malawi, Chichiri, Malawi; Novartis Vaccines Institute for Global Health, Sienna, Italy; and the University of Birmingham, England.