How Salmonella Survives The Human Immune Response

Researchers at the University of California – Irvine have discovered how Salmonella survives the human body’s attempts to destroy it.

About 40,000 cases of salmonellosis, the infection caused by Salmonella, are reported in the U.S. each year, according to the Centers for Disease Control and Prevention (CDC). Those who are sickened have symptoms including diarrhea, fever, and abdominal cramps. Most people recover without treatment, but in severe cases hospitalization is required.

How does Salmonella make so many of us sick?

Salmonella and other pathogens thrive by acquiring metal ions, such as zinc, from the body. When our immune systems detect the presence of a pathogen, they flood the infected area with antimicrobial proteins including calprotectin, which removes zinc. Deprived of this element, most pathogens eventually die. But Salmonella comes prepared.

Salmonella deploys special transporter proteins that can seek out zinc even at the reduced, post-immune response levels. Thanks to its transporter proteins Salmonella can survive the initial immune response and, because calprotectin kills off good microbes that help the immune system fight pathogens, Salmonella can thrive because it meets less resistance.

“We’re beginning to learn more about the mechanisms that allow pathogens like Salmonella to evade our natural defenses and make us sick,” said lead researcher Manuela Raffatellu, a UCI assistant professor of microbiology & molecular genetics, in a statement. “In light of this, if we can devise therapies that block the acquisition of zinc and other metals by Salmonella specifically, we can fight this infection.” The findings may also influence treatment for other illnesses, such as inflammatory bowel disease and colon cancer, she said.

In 2011, there were eight multi-state, foodborne Salmonella outbreaks, according to the CDC.