Researchers Found Animal Virus in Pig Heart Transplanted Into Man Who Later Died

Researchers may be one step closer to determining what killed David Bennett Sr.—the first-ever recipient of genetically modified pig heart.

The 57-year-old Maryland man underwent the experimental surgery back in January, after he was deemed a bad candidate for a human heart transplant or artificial heart pump. During the procedure, doctors noticed Bennett’s aorta was beginning to come apart, so they implanted a graft and stent to prevent further complications. Other than the artery incident, the surgery was initially deemed a success; however, Bennett began experiencing severe health problems just weeks after surgery.

According to USA Today, the man’s recovery was far from smooth. Doctors reportedly had to perform not one, but two surgeries on his abdomen to treat an intestinal infection. He was later prescribed a mix of antibiotics, antiviral medication, and an immune-boosting treatment, but he ultimately died in March after his pig heart became swollen with fluid and stopped functioning. 

On Thursday, researchers confirmed they had found an animal virus harbored inside the pig heart Bennett had been carrying for months. It’s unclear if the virus—called porcine cytomegalovirus—was the cause of Bennett’s death, as they found no signs that the organ had caused active infection in the patient. Doctors also said there were no signs that the pig organ was being rejected by Bennett’s body.

Researchers say the pig that provided the heart was considered healthy, and was subjected to a variety of tests ordered by the Food and Drug administration. Revivicor, the biotech company that raised the animal, has not commented.

“What was the virus doing, if anything, that might have caused the swelling in his heart?” said Dr. Bartley Griffith, the surgeon who performed the historic transplant. “Honestly we don’t know.”