By Margarita Nahapetyan
A common virus, called cytomegalovirus, or CMV, may be a major cause for high blood pressure, researchers from the United States reported last Thursday.
Between 50 and 80 per cent of American adults are infected with CMV by the time they become forty years of age. In the average healthy individual no symptoms of the virus are being observed and there are no long-term disabilities associated with the infection. Like with all the other viruses, once people get CMV, it is going to stay with them for the rest of their life. Cytomegalovirus is part of the herpes virus family, which includes the herpes simplex viruses (cold sores), the virus which causes chicken pox, and infectious mononucleosis. Transmission can come from urine, saliva, and other bodily fluids of an infected person.
CMV appears to cause inflammation in the blood vessels, which over the long period of time can result in high blood pressure. A CMV infection, combined with a fatty diet may also cause hardening of the arteries, a major risk factor for heart attacks, strokes and kidney disease, the experts said. One billion people all across the world suffer from high blood pressure, and the results of this study over the long term may totally change methods of treatment in high blood pressure patients.
Our findings may suggest a completely new way of treating high blood pressure and heart disease, said Dr. Clyde Crumpacker of Harvard Medical School and Beth Israel Deaconess MedicalCenter in Boston, who worked on the study in the Public Library of Science Journal Pathogens. He also added that his investigation found the first direct evidence that the CMV causes chronic infection in blood vessels. Physicians generally use drugs such as beta blockers and ACE inhibitors in order to regulate blood pressure, but, according to Dr. Crumpacker, vaccines and antiviral drugs may offer a new and better treatment options. At present time, there is no vaccine to treat the condition, but several companies, such as Novartis and GlaxoSmithKline PLC, are working on them.
The findings were based on two experiments with four groups of mice. Two sets were assigned to eat a standard diet and two other groups were fed a diet high in fat. Four weeks later, with no other differences between the groups, half of the mice from the standard group and half of the mice from the fatty diet group, were exposed to the virus. When the scientists examined subjects in all groups six weeks later, they found that the mice in both virus infected groups had elevated blood pressure, but 30 per cent of the mice from the fatty diet group, also demonstrated signs of atherosclerosis, a major risk factor for heart attacks, strokes and kidney disease.
In another experiment on kidney cells in infected mice, the experts found high levels of the enzyme rennin, which is known to be causing high blood pressure. The same high levels of the enzyme were observed in human blood cells that have been infected with the virus. In 98 per cent of the cases the cause of human high blood pressure remains unclear, but if cytomegalovirus is established as a cause, the scientists promise to find the ways for better methods of prevention and treatment.
The results strongly suggest that the CMV infection along with the high-cholesterol diet might be working together, Dr. Crumpacker said and concluded that much more studies are needed in order to determine what role viruses play in causing vascular disease.