Common virus may cause high blood pressure-study

A common virus may be a major cause of high blood pressure, researchers said on Thursday when they released a finding that may bring new approach to treating a condition that affects an estimated 1 billion people worldwide.

Cytomegalovirus (CMV) is a virus that affects some 60 to 99 percent of adults globally, and appears to increase inflammation in blood vessels, causing high blood pressure.

And when combined with a fatty diet, CMV may also cause hardening of the arteries, a major risk factor for heart attacks, strokes, and kidney disease, they said.

"I think it could be very important," said Dr. Clyde Crumpacker of Harvard Medical School and Beth Israel Deaconess Medical Center in Boston, who worked on the study in the Public Library of Science Journal PLoS Pathogens.

"It may suggest a whole new way of looking at high blood pressure and vascular disease," Crumpacker said in a telephone interview.

He said the research offers the first direct proof that the virus causes persistent infection in blood vessels. Doctors typically use drugs such as beta blockers and ACE inhibitors to control blood pressure, a condition that affects one in every three adults in the United States.

Crumpacker said the study suggests vaccines and antiviral drugs may offer a new approach at treating hypertension.

Currently, there is no vaccine, but several companies, including Sanofi-Aventis , Novartis , GlaxoSmithKline PLC and Vical , are working on them.

And Swiss drugmaker Roche Holding AG makes an antiviral drug called Valcyte to prevent CMV infections in transplant recipients.

CMV AND DIET

By age 40, most adults will have been exposed to CMV, although many never experience any symptoms. But the virus can cause harm in people with compromised immune systems, such as transplant recipients, and it is a major cause of birth defects in babies whose mothers were infected during pregnancy.

In one experiment, Crumpacker and colleagues examined four groups of lab mice. Two were fed a standard diet and two were fed a high fat diet. After 4 weeks, half of the mice from the standard and fatty diet groups were exposed to the virus.

Six weeks later, mice in both infected groups had elevated blood pressure, but 30 percent of infected mice on high cholesterol diet also showed signs of atherosclerosis.

"This strongly suggests that the CMV infection and the high cholesterol diet might be working together," Crumpacker said.

In another study of kidney cells in infected mice, the team found high levels of the enzyme renin, which is known to cause high blood pressure. They found the same high rates of the enzyme in human blood vessel cells infected with CMV.

And they found that CMV infection increased markers for inflammation in blood vessels.