September 30, 1999

Baboon Liver Passes Virus To Man

By Maggie Fox, Health and Science Correspondent

SAN FRANCISCO (Reuters) - A man who received a baboon liver in an experimental transplant became infected with a virus from the animal -- which throws another obstacle in the way of efforts to make animal-to-human transplants possible, researchers said Wednesday.

The man, a 35-year-old HIV patient, died of his liver disease just over two months after the transplant, which took place in 1992 amid great publicity.

But tests of his tissues in later years show he became infected with a virus from the baboon whose organ he received, Marian Michaels of the University of Pittsburgh said.

"This was the first time that a virus has actually been cultured from a person who received an animal transplant," Michaels told a meeting of infectious disease experts sponsored by the American Society for Microbiology.

The patient was suffering from liver damage caused by the hepatitis B virus, and had had his spleen removed after a car accident a few years before, so he was very ill.

He received the baboon liver in an experimental procedure. He was given a full load of antibiotics, plus the antiviral drug ganciclovir. He and the baboon were also infected with a herpes virus known as cytomegalovirus (CMV).

Baboons are known to carry CMV -- about 98 percent of all animals in the wild and in the laboratory are infected. It does them no harm.

But CMV, which also infects many humans, was believed to be species-specific. That is, the strain that infects one species such as baboons, was not believed to be able to infect humans.

"I think it is quite concerning that an animal virus thought to be species-specific could be transmitted," Michaels said.

The patient took ganciclovir for the first 18 days after the transplant, but had to stop it because of side-effects.

Samples taken 28 days after the transplant showed he was clearly infected with the baboon's CMV.

He had been put back on the ganciclovir and tests showed that the patient was clear of the virus after 35 days. Michaels said it is possible the drug killed the virus.

She said the finding strikes a blow to the idea that primates could be used for animal-to-human transplants, although she described the case of a 25-year-old AIDS patient who got a bone marrow transplant from a baboon who had been quarantined from birth and who was thus free of CMV.

Michaels said it would be possible to raise animals in totally sterile conditions for use in transplants, but doing this with primates would raise ethical issues.

Because of the risk of unknown infections, the U.S. Food and Drug Administration and the Centers for Disease Control and Prevention (CDC) have put a moratorium on animal-to-human transplants.

Dr. John Fung of Pittsburgh earlier told the meeting that the need for animal organs is dire.

He said 20,000 to 30,000 people are waiting for livers now in the United States alone . "That number will increase by 15 to 20 percent a year, while the number of (human organ) transplants available will increase by two to three percent," he said.

The government says least a million people are infected with hepatitis C, which can lead to irreversible liver damage.

Copyright Reuters Limited 1999

[A correction: the U.S. Food and Drug Administration (FDA) and Centers for Disease Control and Prevention (CDC) have NOT "put a moratorium on xenotransplants." On April 6, 1999, the FDA published guidelines that instituted a de facto ban on nonhuman primate xenografts because of "significant infectious disease risk." However, this is only a guideline and is NOT a true ban. Moreover, there is no official ban or moratorium on the use of cells, tissues or organs from pigs, transgenic or otherwise. In fact, limited clinical trials with porcine cells are on-going in the U.S. and elsewhere.]