Virus may boost immune system, study finds

July 3 (UPI) -- Researchers have discovered a virus may help an aging immune system, based on research involving mice.

In a study of the aging immune system, researchers at the University of Arizona found cytomegalovirus, which is linked to the herpes virus, can actually boost the immune system. Their findings were published Monday in the journal Proceedings of the National Academy of Sciences.

As people age, immune systems decline and bodies have a more difficult time fighting off new infections.

"This study shows us that there is more capacity in the immune system at an older age than we thought," Dr. Megan Smithey, a research assistant professor at Arizona's Center on Aging, said in a press release.

"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."

Cytomegalovirus is a virus people usually contract at a young age but it lingers in the body. The virus becomes particularly prevalent in older adults. Symptoms include fever, chills, sweats, decreased appetite, enlarged lymph nodes, sore throat and headache.

"CMV doesn't usually cause outward symptoms, but we still have to live with it every day since there's no cure," Smithey said. "Our immune system always will be busy in the background dealing with this virus."

Mice were infected with cytomegalovirus.

"We assumed it would make mice more vulnerable to other infections because it was using up resources and keeping the immune system busy," Smithey said.

But when infected with listeria, old mice with CMV were tougher than ones without the virus.

Both groups had a good supply of diverse T-cells, which fight off infection.

"Diversity is good," Dr. Janko Nikolich-Zugich, co-director or Center on Aging said. "Different types of T-cells respond to different types of infections; the more diverse T-cells you have, the more likely you'll be able to fight off infections."

Although T-cells are almost as diverse in all age levels of mice, they aren't utilized unless they are infected with CMV, the researchers said.

"It's as if CMV is issuing a signal that gets the best defenses out onto the field," Nikolich-Zugich said.

The researchers hope to study the virus in humans and ultimately create a vaccine that can protect older people against infection.