23.05.2012

Eye infections "can cause AMD"

Eye infections "can cause AMD"

By Adrian Galbreth

For many years, eye specialists have believed that the development of age-related macular degeneration (AMD), one of the leading causes of blindness on the planet, was either the result of genetic predispositions or lifestyle factors such as smoking or a high fat diet.

However, a new study carried out in the US has indicated that the manifestation of the harmful condition can also be caused by a type of eye infection - specifically the human cytomegalovirus, a variant of the herpes virus.

A team led by professor Richard Dix, from the Georgia State Viral Immunology Center's Ocular Virology and Immunology Laboratory, found that the virus causes the production of vascular endothelial growth factor (VEGF) a signal protein that regulates the formation of new blood vessels.

In the study, published in PLoS Pathogens, a journal of the Public Library of Science, Professor Dix explains how the formation of new blood vessels leads to retinal tissue destruction, which in turn results in the development of wet AMD.

The expert noted that around 80 per cent of the population is estimated to have antibodies for the virus, which is often acquired during childhood, and explained that the virus becomes latent in the cells of bone marrow and blood in people with a normal, healthy immune system.

However, in the elderly, the immune system's function is reduced, the virus proliferates, and the production of VEGF increases.

Professor Dix said that identifying human cytomegalovirus as a cofactor in the development of AMD can open up new paths for the treatment of AMD, with one possible route including the reduction of the amount of the human cytomegalovirus in the blood stream through treatment with an antiviral drug known as ganciclovir.

"If we can knock down a certain gene or genes of the virus that stimulates VEGF production, we might be able to decrease it production and minimise AMD," the expert concluded.

by Martin Burns


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