Recipient of the First-Ever Pig Heart Transplant Died Possibly Because of the Animal’s Virus

The plausibility that a pig virus could adapt to cause infection in humans as an outcome of a transplant has worried scientists who hope interspecies transplants could eventually help address the dire shortage of human donors.

A Forbes report specified that the Maryland man who died of unclear cause two months following receipt of the first-ever transplant of a genetically altered pig heart may have been the "victim of a pig virus" associated with transplant failure, the doctor of the patient found.

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Due to the risk of hazardous cross-species disease transmission, recipients of animal transplants and their contacts, which include pets, need to be checked at regular intervals, a team of transplant researchers reported in a 2013 paper published by the National Center of Biotechnology Information.

Nonetheless, porcine cytomegalovirus is not believed to be able to cause infections in humans, Jay Fishman, a transplant infection specialist at Massachusetts General Hospital, said.

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(Photo: Ulet Ifansasti/Getty Images)
This pig virus is present anywhere in the world and exists in the majority, if not all, of swine populations.

Testing Approaches for Pig-to-Human Transplants

As indicated in an MIT Technology Review, Baboons have been used to test approaches for pig-to-human transplants and have exhibited the danger posed by the said pig virus.

A study published in 2015 showed that pig-to-baboon kidney grafts were unsuccessful almost four times more rapidly when the virus was present. A study published in the Nature journal in 2020 showed that pig-to-baboon heart transplants with the virus failed fast while virus-free transplants could last longer than six months.

Authors of this Nature study said infected hearts exhibited extremely high levels of the virus, probably because of the intentional inhibition of the immune system of the baboon during transplantation or because of the absence of the immune system of the pig, which might have been more appropriate to stop a pig-specific virus.

A human who received a heart infected with porcine cytomegalovirus would likely suffer the same shortened survival time, said the researchers.

Porcine Cytomegalovirus

Pig333.com describes porcine cytomegalovirus as herpes found in all body tissue, including newborn piglets' snouts, which particularly produce inflammation or rhinitis.

This pig virus is present anywhere in the world and exists in the majority, if not all, of swine populations.

Essentially, rhinitis resulting from this virus is infrequent and takes place mostly in newborn piglets and the nursery. It is not associated with atrophic rhinitis caused by Toxigenic Pasteurella multocida and Bordetella bronchiseptica.

In most farms, the level of infection is extremely low. It's causing sporadic, mild sneezes without any major impact on the pig's health.

Symptoms and Prevention of the Pig Virus

Newborn piglets infected with rhinitis can be serious enough to cause nasal hemorrhage. In addition, in farms where the virus is endemic, the only symptom includes mild sneezes in nursing and weaned piglets.

Since the virus is rarely recognized as a cause of severe loss, control measures are frequently ignored.

Furthermore, growing pigs are typically protected from large losses by antibodies given by their immune dams. As piglets grow, they become exposed to the virus in the environment and respond by generating their antibodies.

Environmental conditions are poor; they need some improvements. Herd immunity through acclimatization of breeding stock is usually practiced.

There is no identified effective medication or treatment for this pig virus. Antibiotics may help control concurrent diseases or secondary bacterial infections.

A report about the first-ever pig-to-human heart transplant is shown on NBC News's YouTube video below: