Warning over animal organs

In the week that the Department of Health was expected to publish a report supporting animal to human organ transplantation, a leading scientist warned that such transplants could result in the spread of deadly viruses.

The inquiry on xenotransplantation, chaired by Ian Kennedy, professor of medical law and ethics at King's College, London, is understood to have concluded that the benefits of animal to human tranplants are so great, and the shortage of human donors so serious, that the procedure is ethically acceptable.

But Robin Weiss, professor of virology at the Institute of Cancer Research in London, warned that Britain might still be years away from carrying out the first safe organ transplant from animals to humans.

Years of work may still be needed to clean up and screen donor pigs before such a transplant went ahead safely, he said.

Professor Weiss's laboratory has been studying whether tranplantation of organs such as hearts from animals to humans could lead to virus transfer. It has found that at least one strain of pig retrovirus, when transferred to human cells in the lab, can take and grow.

"We don't know if the virus could do harm to humans," said Professor Weiss.

He added that a transplant patient, whose body had already been immuno-suppressed so it was more likely to accept the transplant, was less likely to be able to reject the virus. Attempts to modify pigs genetically so that their cells are more acceptable to humans also meant that foreign viruses were less likely to be destroyed immediately.

"I am worried that they will go ahead with transplants at once," said Professor Weiss. "What I am concerned about is that it might set off something that runs and runs and becomes an epidemic. It's better to be wise before the event."