Common virus may cause high blood pressure-study

CHICAGO (Reuters) – A common virus may be a major  cause of high blood pressure, researchers said on Thursday in a  finding that may bring new approach to treating a condition  that affects an estimated 1 billion people worldwide.

Based on a series of studies in mice, they said  cytomegalovirus or CMV — a herpes virus that affects some 60  to 99 percent of adults globally — 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 generic 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 for 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.More research is needed looking at the role of viruses in  causing heart disease, but Crumpacker said the findings suggest  new treatment possibilities.

“Some cases of hypertension might be treated or prevented  by antiviral therapy or a vaccine against CMV,” he said.