Viral Infection Linked to Blinding Eye Disease

Herpesvirus type associated with wet age related macular degeneration

(RxWiki News) Age-related macular degeneration (AMD) is a leading cause of blindness in older adults. However, few risk factors for the eye disease have been identified. A viral infection has now been linked to development of AMD.

A type of herpes virus called human cytomegalovirus has been found to be linked to development of AMD.

"Ask your ophthalmologist about your risk for AMD."

Richard D. Dix, professor at the Georgia State Viral Immunology Center's Ocular Virology and Immunology Laboratory and an adjunct professor of ophthalmology at the Emory University School of Medicine, said that prior to the recent finding, the only other known factors for developing AMD were genetics, smoking and a high-fat diet.

During the preclinical study, scientists found that human cytomegalovirus causes the production of vascular endothelial growth factor (VEGF), a protein that regulates the formation of new blood vessels.

When new blood vessels begin forming uncontrollably, retinal tissue is destroyed, leading to the development of the more severe "wet" form of AMD. This can eventually lead to blindness.

Dix called human cytomegalovirus a common herpes virus often acquired during childhood. About 80 percent of the population is estimated to have antibodies for the virus.

In individuals with healthy immune systems, the virus tends to remain dormant in the bone marrow and blood. However, immune system function is reduced among older adults, allowing the virus to proliferate and VEGF production to increase.

Identifying the virus as a co-factor could lead to new treatment options, such as an attempt to reduce the viral load in the blood stream through antiviral therapy.

Researchers also could examine upregulation of VEGF by human cytomegalovirus.

"If we can knock down a certain gene or genes of the virus that stimulates VEGF production, we might be able to decrease production and minimize AMD," Dix said.

The findings were recently published in PLoS Pathogens, a journal of the Public Library of Science.

Review Date: 
May 22, 2012