Cause of Herpes Virus Reactivation Revealed

Researchers are now understanding how and why viruses like herpes can remain dormant for long periods of time, and then suddenly reactivate. The key is in interactions with other viruses. 

As many as 95% of US adults have been infected with at least 1 of the 8 strains of herpes virus, which cause diseases such as cold sores, chicken pox, mononucleosis, and cancer.
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However, unlike most viruses that are attacked and destroyed by the body’s immune system, herpes remains in the body forever.

“The question has been: What happens to reactivate these viruses to cause disease?” researchers wrote.

In their study, researchers focused on herpes virus 8, which causes Kaposi’s sarcoma cancer, first using infected mice and later duplicated their findings in infected human cells.  

They found that after initial infection, a protein called interferon gamma keeps the virus from reactivating. When specimens were later infected with helminth worms, a common parasite in sub-Saharan Africa, the body responded by releasing a protein called interleukin 4, which not only blocked interferon gamma but activated herpes virus reproduction.

“The fact that the virus can ‘sense’ the immune reaction to a worm and respond by reactivating is a remarkable example of co-evolution,” wrote lead author Herbert W. Virgin IV, MD, PhD, of Washington University in St. Louis, MO. 

“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.”

The full study is available in the June issue of Science.

–Michael Potts

Reese TA, Wakeman BS, Cho HS, Hufford MM, et al. Helminth infection reactivates latent y-herpesvirus via cytokine competition at a viral promoter. Science. 2014 June 26 [epub ahead of print] doi: 10.1126/science.1254517

University of Florida. New infections cause dormant viruses to reactivate [press release]. June 26, 2014. http://news.ufl.edu/2014/06/26/dormant-herpes-activation/. Accessed June 27, 2014.