New Zealand scientists are developing a new vaccine for tuberculosis in cows which may also help millions of human victims of the disease.

The scientists, at AgResearch's Wallaceville research centre near Wellington, expect to be ready to test the vaccine in cattle and possibly wild possums within five years.

AgResearch science manager Paul Atkinson has told Parliament's education and science committee that the TB vaccine was the only genetically modified organism (GMO) that the institute expected to test outside containment in the first five years after the moratorium on releasing GMOs ends in October.

"A TB vaccine in cows might also be a vaccine in human beings in the Third World," he said

"What the developed world needs is a better drug. What the Third World needs is a vaccine for animals and humans because they can't afford drugs, and their farming practices are such that a vaccine would break the transmission mechanism.

"The contact between humans and animals is much closer in many Third World countries."

About 10 million people a year contract tuberculosis, a disease caused by bacteria which block the victim's lungs. It kills 3.5 million people, including about 15 in New Zealand, each year.

Disease rates have dropped dramatically in rich countries during the past 200 years with widespread injections of BCG, a compound including a small dose of TB bacteria to help the body develop immunity against it.

But AgResearch scientist Geoff de Lisle said BCG did not work for many people and scientists around the world were looking for a better option.

In New Zealand, TB is more common in cattle, deer and possums than in humans.

The number of infected cattle and deer herds has dropped from 1700 in 1994 to 400 today, mainly by spending millions of dollars on possum control.

AgResearch hopes to develop a new vaccine by "knocking out" up to 10 genes in the bacteria that cause TB in cows, making the modified bacteria safe to inject into cows - and potentially into people.

"We have identified genes which can cause disease. If you remove those, you can end up with an organism that no longer causes disease, and some of those organisms perform well as vaccines," Dr de Lisle said.

"What we are doing is state-of-the-art. We are not following the pack, we are up there in front."

Dr Atkinson said that if the project found a successful vaccine, AgResearch would look to an international pharmaceutical company to put up the hundreds of millions of dollars that would be needed to get worldwide approvals to use it.

AgResearch has announced plans to close its Wallaceville research centre and shift its work mainly to Palmerston North and Dunedin. Dr Atkinson said it had not been decided what would happen to the TB research if the closure went ahead.