Featured Research

from universities, journals, and other organizations

Fighting parasitic infection inadvertently unleashes dormant virus

Date:
June 26, 2014
Source:
Washington University in St. Louis
Summary:
Signals from the immune system that help repel a common parasite inadvertently can cause a dormant viral infection to become active again, a new study shows. Further research is necessary to understand the clinical significance of the finding, but researchers said the study helps illustrate how complex interactions between infectious agents and the immune system have the potential to affect illness.

Heligmosomoides polygyrus is a natural intestinal parasite of mice, which can provide a model of helminth infections in humans. When such a parasite infects mice, some of the signals that the animal’s immune system produces to defend against it can activate a latent viral infection.
Credit: By D. Davesne (Own work) [CC-BY-SA-3.0], via Wikimedia Commons

Signals from the immune system that help repel a common parasite inadvertently can cause a dormant viral infection to become active again, a new study shows.

Further research is necessary to understand the clinical significance of the finding, but researchers at Washington University School of Medicine in St. Louis said the study helps illustrate how complex interactions between infectious agents and the immune system have the potential to affect illness.

The results appear online June 26 in Science Express.

The scientists identified specific signals in mice that mobilize the immune system to fight tapeworms, roundworms and other helminths, parasites that infect nearly a quarter of all humans. The same signals cause an inactive herpes virus infection in the mice to begin replicating again.

The researchers speculated that the virus might be taking advantage of the host response to the worm infection, multiplying and spreading when the immune system's attention is fixed on fighting the worms.

"The fact that the virus can 'sense' the immune reaction to a worm and respond by reactivating is a remarkable example of co-evolution," said senior author Herbert W. Virgin IV, MD, PhD. "We think other interactions between multiple infectious agents and the immune system will be discovered over time that we will view as similarly sophisticated or maybe even devious. Understanding these interactions will help us survive in a complex microbial world."

Viral infections typically begin with a battle with the host's immune system. That clash may eliminate many copies of the virus, but some can survive and hide in the nucleus of long-lived host cells without replicating, entering a phase known as latency.

Scientists have observed several examples of latent viral infections becoming active again after parasitic infections, such as malaria. The new study is the first to show that this reactivation can be triggered by immune system signals, and is also the first to identify genetic elements in the virus that direct its reactivation from latency.

The researchers gave mice a virus similar to human Karposi's sarcoma-associated herpes virus, a virus that causes cancers common in AIDS patients. After the infection became latent, the researchers infected the mice with parasitic helminth worms. The parasite then caused the mouse immune system to make cytokines, signaling molecules that help summon the immune cells and other factors needed to attack the parasites.

But the same cytokines also caused the herpes virus to start reproducing.

"Viruses become latent because they can detect immune system signals that tell them not to replicate," said first author Tiffany Reese, PhD, the Damon Runyon Postdoctoral Fellow in Virgin's lab. "Now, for the first time, we've shown a virus can detect immune system signals that tell the virus to start replicating. The signals are a response to the parasite infection, but the virus has developed a way of 'eavesdropping' on that response."

Virgin, the Edward Mallinckrodt Professor and Head of Pathology and Immunology, emphasized that the finding only applies to a particular class of herpes viruses that does not include herpes simplex, a common cause of sexually transmitted disease, or cytomegalovirus, which causes problems in patients with compromised immune systems.

"The human health consequences of reactivating this type of virus are unclear," he said. "We need to learn much more about how common these types of interactions are between multiple types of pathogens and the immune system before we can consider the implications for clinical treatment. And now we've identified an important place to begin asking those kinds of questions."

Funding from the National Institutes of Health (NIH) (U54 AI057160, RO1 CA96511, and AI032573) supported this research.


Story Source:

The above story is based on materials provided by Washington University in St. Louis. The original article was written by Michael C. Purdy. Note: Materials may be edited for content and length.


Journal Reference:

  1. Reese TA, Wakeman BS, Choi HS, Hufford MM, Huang SC, Zhang X, Buck MD, Jezewski A, Kambal A, Liu CY, Goel G, Murray PJ, Xavier RJ, Kaplan MH, Renne R, Speck SH, Artyomov MN, Pearce EJ, Virgin HW. Helminth infection reactivates latent gamma-herpesvirus via cytokine competition at a viral promoter. Science, June 26, 2014 DOI: 10.1126/science.1254517

Cite This Page:

Washington University in St. Louis. "Fighting parasitic infection inadvertently unleashes dormant virus." ScienceDaily. ScienceDaily, 26 June 2014. <www.sciencedaily.com/releases/2014/06/140626141015.htm>.
Washington University in St. Louis. (2014, June 26). Fighting parasitic infection inadvertently unleashes dormant virus. ScienceDaily. Retrieved July 28, 2014 from www.sciencedaily.com/releases/2014/06/140626141015.htm
Washington University in St. Louis. "Fighting parasitic infection inadvertently unleashes dormant virus." ScienceDaily. www.sciencedaily.com/releases/2014/06/140626141015.htm (accessed July 28, 2014).

Share This




More Health & Medicine News

Monday, July 28, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Deadly Ebola Virus Threatens West Africa

Deadly Ebola Virus Threatens West Africa

AP (July 28, 2014) West African nations and international health organizations are working to contain the largest Ebola outbreak in history. It's one of the deadliest diseases known to man, but the CDC says it's unlikely to spread in the U.S. (July 28) Video provided by AP
Powered by NewsLook.com
$15B Deal on Vets' Health Care Reached

$15B Deal on Vets' Health Care Reached

AP (July 28, 2014) A bipartisan deal to improve veterans health care would authorize at least $15 billion in emergency spending to fix a veterans program scandalized by long patient wait times and falsified records. (July 28) Video provided by AP
Powered by NewsLook.com
Two Americans Contract Ebola in Liberia

Two Americans Contract Ebola in Liberia

Reuters - US Online Video (July 28, 2014) Two American aid workers in Liberia test positive for Ebola while working to combat the deadliest outbreak of the virus ever. Linda So reports. Video provided by Reuters
Powered by NewsLook.com
Traditional African Dishes Teach Healthy Eating

Traditional African Dishes Teach Healthy Eating

AP (July 28, 2014) Classes are being offered nationwide to encourage African Americans to learn about cooking fresh foods based on traditional African cuisine. The program is trying to combat obesity, heart disease and other ailments often linked to diet. (July 28) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins