This virus actually may boost—not weaken—our immune system

July 2, 2018, University of Arizona
This virus actually may boost -- not weaken -- our immune system
Janko Nikolich-Zugich, M.D., Ph.D. Credit: UA College of Medicine - Tucson

Our immune system is at its peak when we're young, but after a certain age, it declines and it becomes more difficult for our bodies to fight off new infections.

"That's why older people are more susceptible to infections than younger people," explains Janko Nikolich-Zugich, MD, Ph.D., co-director or the University of Arizona Center on Aging and chairman of the Department of Immunobiology at the University of Arizona College of Medicine—Tucson.

In search of a way to rejuvenate the immune system of older adults, Dr. Nikolich-Zugich and Megan Smithey, Ph.D., have found that one particular virus may not weaken, but actually enhance our immune system. Their findings are published this week in the Proceedings of the National Academy of Sciences.

For the study, the researchers infected with the cytomegalovirus (CMV). The virus affects more than half of all individuals and is contracted, for most part, at a young age. Because there is no cure, the virus is carried for life, and is particularly prevalent in older adults.

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

Drs. Smithey and Nikolich-Zugich wondered how this lifelong virus ultimately affects the immune system.

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

But that's not what happens.

When infected with listeria, old mice carrying CMV proved to be tougher than old mice without CMV.

"We were completely surprised; we expected these mice to be worse off," Smithey says. "But they had a more robust, effective response to the infection."

The researchers are not certain how CMV strengthens the immune system—they are investigating that in a separate study—but they do believe they have gained new insight into the aging immune system.

"This study shows us that there is more capacity in the immune system at an older age than we thought," Dr. Smithey says.

When the researchers examined the mice's T-cells—the army of defenders that fights off infection—they found that both groups of older mice had a decent supply of diverse T-cells.

"Diversity is good," Dr. Nikolich-Zugich says. "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."

For years, immunobiologists assumed that T-cell diversity decreased as we age. This was one of the reasons why older adults succumbed to disease more easily.

But Drs. Smithey and Nikolich-Zugich's new study shows that T-cells are almost as diverse in old mice as they are in young mice. The problem is that diverse T-cells are not recruited to the battlefield in older mice—unless they are infected with CMV.

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

"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," Dr. Smithey adds.

The UA College of Medicine—Tucson team plans to continue to study CMV. It hopes to see similar results in human studies. The team's ultimate goal is to create a vaccine that can improve the immune system of and protect against .

Explore further: Boosting immunity in older adults: Study unmasks new infection-fighting T cells

More information: Megan J. Smithey el al., "Lifelong CMV infection improves immune defense in old mice by broadening the mobilized TCR repertoire against third-party infection," PNAS (2018). www.pnas.org/cgi/doi/10.1073/pnas.1719451115

Related Stories

Boosting immunity in older adults: Study unmasks new infection-fighting T cells

June 13, 2016
Sixty-five is the age when many people retire, kick back and take it easy. And so it often is with the human immune system.

Presence of common infection—cytomegalovirus—helps to explain increased other virus susceptibility in aging adults

September 6, 2012
(Medical Xpress)—The first experimental proof that long-term infection with cytomegalovirus, or CMV, may impair the aging immune system's response to unrelated viruses – such as West Nile or the flu – has been published ...

Study: Understanding immunity as we age

January 13, 2014
(Medical Xpress)—Researchers at the University of Arizona College of Medicine – Tucson have found a key to understanding the aging immune system's decreased response to infectious diseases, which remain among the leading ...

How intestinal worms hinder tuberculosis vaccination

May 17, 2018
New research in mice suggests that chronic infection with intestinal worms indirectly reduces the number of cells in lymph nodes near the skin, inhibiting the immune system's response to the Bacille Calmette-Guerin (BCG) ...

Zika-related nerve damage caused by immune response to the virus

November 20, 2017
The immune system's response to the Zika virus, rather than the virus itself, may be responsible for nerve-related complications of infection, according to a Yale study. This insight could lead to new ways of treating patients ...

Recommended for you

The immune system: T cells are built for speed

July 17, 2018
Without T cells, we could not survive. They are a key component of the immune system and have highly sensitive receptors on their surface that can detect pathogens. The exact way that these receptors are distributed over ...

How protein fragments could help to tackle the cause of hay fever

July 16, 2018
Imperial researchers are looking to protein fragments to help people build up resistance to grass pollen.

Team explores diabetes drug's ability to treat RSV infection

July 13, 2018
A drug used to treat diabetes may point to new therapies for respiratory syncytial virus (RSV) bronchiolitis—inflammation and obstruction of the lungs' small airways. A multi-disciplinary team of Vanderbilt investigators ...

Testing suggests TORC1 inhibitors can boost immune system in the elderly

July 12, 2018
A team of researchers affiliated with Novartis Institutes for Biomedical Research and Biometrics Matters Limited, has found via testing with volunteers that TORC1 inhibitors can boost the immune system in the elderly. In ...

Biologists discover process that neutralizes tumors

July 10, 2018
Researchers from the University of California San Diego have identified an unexpected mechanism that could help determine whether a cancer patient will respond to immunotherapy.

Mitochondrial DNA in exosomes is the alarm that initiates the antiviral response

July 10, 2018
Researchers at the Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC) have provided valuable information about the defense mechanisms of the immune system during the early stages of the response to pathogens ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.