In the late 1990s, a London-based research team confirmed that PERVs could infect human cells, at least in a laboratory setting.
The discovery “temporarily killed xenotransplantation,” said Björn Petersen, a xenotransplantation researcher at the Friedrich Loeffler Institute, the German government’s research center for animal diseases. “Pharmaceutical companies have withdrawn their money from research.”
Pigs that were as disease-free as possible were hunted worldwide.
1998 diatrance Partner Olga Garkavenko turned on her radio and caught wind of Invercargill’s newcomers. She decided to do some research.
The company received tissue samples from the quarantined pigs for analysis. The harsh conditions on the islands seemed to have added to the disease.
“They stayed isolated and therefore remained free from many common infections that you get in pigs,” Tan said. “The weak pigs were probably wiped out. Only the strongest survived.”
The pigs also have an unusually low number of retrovirus copies in their genome. Petersen noted that the population is also completely free of a type of PERV called PERV-C, which may pose the greatest risk to human transplant recipients. This is possible “because they were isolated for a long time and never had contact with other pigs”.
Joachim Denner, a xenotransplantation researcher at Freie Universität Berlin, said the Auckland Island pigs have another major advantage over other pig breeds – their small stature. Weighing around 90 pounds, he said, “they’re the right size for a transplant.” A domestic pig weighs 300 to 700 pounds, and its organs are oversized, he added.
In 2004, Elliott, Tan and others formed a company called Living Cell Technologies, or LCT, to take on diatranz and take care of the pigs, building an expensive facility near Invercargill to keep them in medical isolation while they selectively bred for xenotransplantation.
The quarantined animals suddenly gained a reputation for being worth hundreds of thousands of dollars each, much to then-Mayor Shadbolt’s barely concealed delight.
The project brought jobs and millions of dollars in investment to Invercargill. “It all came to fruition,” Shadbolt said in 2008 Otago Daily Times Article. “I rub it into people who haven’t supported me on every occasion.”
In the 2010s Concerns about PERVs eased as several cell transplant clinical trials suggested not only that pig cells might be effective in treating diabetes, but also that PERVs do not spread to humans. New gene-editing technology also meant that retrovirus genes could be rendered inoperable before an animal was born.
With these advances, the race to successfully implant pig organs in humans has accelerated. Groups around the world are now breeding pigs for this purpose. It’s big business – a recent report estimates that the global xenotransplantation market could be worth US$24.5 billion by 2029.
In January 2022, a group from the University of Maryland performed the first successful transplant of a pig heart into a living patient using a pig organ from the US company Revivicor. The patient survived two months. While the cause of death is still under investigation, an autopsy found evidence of a disease called porcine cytomegalovirus. The pig used for the transplant, Tan said, would have been rigorously screened for the virus, which, he added, shows the importance of breeding pigs truly free of such diseases.