Dr Una Ryan explains how the vaccine boosts the immune system

It works by raising levels of "good" cholesterol and unclogging arteries.

The drug has shown promising results in animal tests.

Researchers say it boosts the body's natural ability to cope with cholesterol, but one GP has warned that a vaccine could leave the body open to other forms of disease.

The researchers at Avant Immunotherapeutics said their vaccine raised levels of high-density lipoprotein - HDL or "good" cholesterol - by 35% in rabbits.

It also reduced the number of plaques - which clog up arteries - by 40%.

Boosting the body's immune system

Dr Una Ryan is president and chief executive officer of company, based in Needham, Massachusetts.

Researchers hope the vaccine will prevent heart disease

She said the vaccine gets the body's natural defences to do all the hard work.

"This is self-help, your own body, your own immune system, doing the work for you.

"What we're doing here is giving a little part of a molecule that's in everybody and teaching the immune system to react against it and lower the levels."

She said the company had high hopes for the human trials, which will take place in the US.

"We are very pleased with these results, which clearly demonstrate the feasibility of our vaccine approach as a novel strategy for preventing or treating atherosclerosis," she said.

"As a result, we are preparing to initiate human clinical safety studies with the vaccine this summer."

Atherosclerosis is an abnormal thickening and loss of elasticity of the walls of the arteries.

Vaccine could create vulnerability

However, Dr Peter Mansfield - a GP opposed to vaccines - said any such vaccine would only make the body lazy.

Dr Peter Mansfield says why the vaccine is a bad idea

He said: "In the long run all these vaccines will ever do is rob Peter to pay Paul - we should not be used to having something taken away for a quick fix now.

"Heart disease is not the only issue here - most of our problems as they are emerging have to do with general immunity.

A margarine also claims to cut cholesterol levels

"If we are asking our immune systems to work too hard because we're lazy in one department, then we're going to be awfully upset when we start getting some new disease as a result of the immune system in general being less vigilant."

Dr Mansfield said the vaccine was only being developed because a company could see how to make a profit out of it.

This was a general problem in modern medicine, he said.

Antibodies target protein

Dr Lawrence Thomas, of Avant, explained how the vaccine works to the Federation of American Societies for Experimental Biology in Washington.

He said the vaccine produces antibodies that block the activity of cholesteryl ester transfer protein (CETP).

CETP is responsible for HDL being converted into low density lipoprotein - LDL or "bad" cholesterol.

While HDL is carried away from arteries, LDL is left in the arteries to cause blockages.