A viral infection may explain why a pig’s heart failed a few months after a transplant as a result of groundbreaking surgery
May 6, 2022
The swine virus may have caused the death of the first person to have a heart transplant from an animal.
David Bennett died in March at the age of 57, two months after a transplant operation. Bennett, who had severe heart failure, was found too sick to get a human heart, and received a pork organ based on compassion. Ten genetic changes were made in the pig-donor to prevent rejection of her organ, four pig genes were removed and six human genes were added.
Bennett at first it seemed that all was wellhowever, doctors behind the transplant have now revealed that they tried to treat the swine cytomegalovirus infection a few weeks before his death.
Transplant Surgeon Bartley Griffith at the University of Maryland announced the presence of cytomegalovirus in Fr. talk to the American Society of Transplantology on April 20th. “We’re starting to find out why he passed away,” he said MIT Technology Review.
MIT Technology Review Griffith reports that the pig’s heart failure may have been caused by a viral infection rather than Bennett’s immune system, which rejects the organ. “There is no evidence that the virus has infected the patient or infected any tissues or organs outside the heart,” said a spokesman for the University of Maryland.
Cytomegaloviruses are herpes viruses that cause cold sores and shingles. After infecting animals, viral DNA remains inside some cells. Their immune system usually keeps the virus under control, but if the animal is weakened, the virus can reactivate and cause further infections.
Bennett would not have been immune to the swine cytomegalovirus, which allowed the virus to reactivate and infect the transplanted heart. The virus does not infect human cells, says Joachim Denner of the Free University of Berlin in Germany. Bennett was also taking immunosuppressive drugs that may have prevented his immune system from fully responding.
The virus was first detected in blood taken 20 days after Bennett’s transplant. The team tried various treatments, including a drug used to treat a human cytomegalovirus infection called cidofovir, and Bennett seemed to have recovered from the rapid deterioration of his condition. When Bennett’s immune system began to respond to the virus, it may have caused an inflammatory reaction known as cytokines, damaging the heart, Griffith says.
In 2020, Denner and his colleagues discovered this baboons do not live that long if they develop swine cytomegaloviruses after a pig heart transplant. But no one can say exactly to what extent the virus contributed to Bennett’s death, Denner says. “He was very, very sick.”
Pigs bred for organs are raised in special clean rooms so that they do not have pathogenic microorganisms. The inability to detect the virus before transplantation could be due to a lack of sensitivity tests, Denner says. He developed sensitivity swine cytomegalovirus testswhich his lab used in 2016 detect the virus in pigs raised for biomedical research. These tests were positive even on samples that were negative when tested in U.S. laboratories.
“The testing that the researcher refers to in your article is experimental [and] was inaccessible to our scientific surgeons during this transplant, ”said a Maryland spokesman when asked if these tests were used by Griffith’s team.
Detecting latent infections – if the viral DNA is in several cells and no viruses are produced – is harder than identifying active infections, but there are two ways to do it. The first is the search for viral DNA in blood or tissue samples. The second is to look for antibodies to the virus. Both methods are used in Denner’s laboratory. It is unclear what tests were performed before Bennett’s transplant.
“A healthy donor pig used for xenotransplantation has been screened for pathogens several times. It was tested just before being sent to Maryland and just before the transplant a few days later. The testing was conducted according to protocols adopted by the U.S. Food and Drug Administration (FDA). Better testing methods are being developed and tested in future clinical trial plans to ensure that the virus does not go unnoticed, ”said a Maryland spokeswoman.
If the virus contributed to Bennett’s death rather than because his immune system rejected that organ, the results of a study by Dener’s baboons suggest that other transplant recipients may live longer if they are given hearts without the virus. Pigs can be guaranteed free of swine cytomegalovirus by weaning the animals 24 hours after birthsays Denner.
Revivicor, a subsidiary of United Therapeutics, developed the pig for Bennett’s transplant and did not comment on the virus’s detection. There is no evidence of violations by companies. None of the firms responded The new scientistrequests comments before publication.
Subscribe to our free Health check a newsletter that gives you health, diet and fitness news every Saturday you can trust
More on these topics:
This article is first published on Source link