Scientists Find Virus That Strengthens, Not Weakens, Immune System

A study by researchers at the University of Arizona published in PNAS has identified a common virus, cytomegalovirus (CMV), that appears to fortify the immune system, according to Newsweek . The researchers note more than 50 percent of all humans carry CMV, which is generally contracted at a young age. The team first infected a group of mice with CMV and then infected both CMV carriers and non-carriers with listeria. "We assumed it would make mice more vulnerable to other infections because it was using up resources and keeping the immune system busy," says the University of Arizona's Megan Smithey. However, the researchers found the immune systems of the CMV-carrying mice were stronger than those of the non-carriers. Moreover, the animals infected with CMV had T cells — white blood cells that play a key role in immunity — that were nearly as variegated as young mice. "It's as if CMV is issuing a signal that gets the best defenses out onto the field," notes the University of Arizona's Janko Nikolich-Zugich. Smithey adds, "This shows that the ability to generate a good immune response exists in old age — and CMV, or the body's response to CMV, can help harness that ability."