Engineering PRRS-Resistant Pigs

Harnessing Genetic Innovation to Improve Pig Health, Welfare, and Sustainability

Porcine Reproductive and Respiratory Syndrome (PRRS) virus is one of the most economically devastating diseases affecting the global pig industry, causing respiratory illness in piglets and reproductive failure in breeding sows. Endemic in over 60 countries, the disease costs producers approximately £1.75 billion globally every year.

Despite rigorous vaccination programs and stringent biosecurity measures, the virus remains persistent and difficult to control. PRRS virus gains entry into pig immune cells by binding to a receptor protein called CD163 on the cell surface. Addressing this molecular vulnerability presented an opportunity for a transformative solution.

 

The Breakthrough: Precision Gene Editing for Resistance

Researchers at the Roslin Institute, part of the Engineering Biology Hub, hypothesised that by precisely removing a small, non-essential section of the CD163 protein, they could block the virus’s entry without compromising the pig’s health. This theory was put to the test using cutting-edge gene-editing technologies applied at the zygote stage, the single-cell phase immediately after fertilisation.

Highly trained specialists used micromanipulation under a microscope to inject gene-editing components into zygotes, which were then transferred into surrogate sows. The resulting pigs were born and raised in high-health-status facilities at the Large Animal Research and Imaging Facility (LARIF) part of the Roslin Institute.

The gene-edited pigs lacked the specific portion of CD163 used by the PRRS virus to infect cells. Importantly, these pigs remained completely resistant to PRRSV and showed no adverse health effects from the gene modification. Meat quality and nutritional value were equivalent to that of non-edited pigs.

 

Scaling Impact: From Research to Market

The project attracted over £1.2 million in funding from the BBSRC, Medical Research Council, and Genus, the global animal genetics company that collaborated to commercialise the innovation through its subsidiary, PIC (Pig Improvement Company).

In April 2025, the U.S. Food and Drug Administration (FDA) approved the gene-editing approach, confirming both the safety and efficacy of the PRRS-resistant pigs. This was a landmark moment: one of the first regulatory approvals for gene-edited livestock in the U.S., setting a precedent for future innovations in sustainable animal agriculture. PIC is now actively pursuing regulatory approvals in other major markets, including Canada, Mexico, Japan, China, Colombia, and Brazil..

 

A Showcase of Engineering Biology in Action

This case study exemplifies how engineering biology can solve complex, real-world challenges in agriculture. The PRRS-resistant pig is more than a scientific milestone, it’s a scalable, sustainable, and ethical solution that offers lasting benefits for animal health, farmer livelihoods, and the global food system.

By bridging cutting-edge science with real-world application, the Engineering Biology Hub and its partners are leading the way toward a more resilient and responsible future for livestock farming.

This work and the fundamental techniques underlying it pave the way for targeting other diseases affecting large animals.

 

A Collaborative Effort and Advanced Infrastructure

This complex project brought together specialists in developmental biology, immunology, virology, veterinary medicine, and animal welfare. Research was supported by the Large Animal and Imaging Facility (LARIF) at the Roslin Institute, that provides:

  • Animal Holding and Handling Units
  • Surgical and Clinical Care Units
  • Imaging Technologies

Animal welfare was a central pillar throughout the project. All procedures were carried out under the highest standards of ethical care, in close partnership with trained animal technicians and the Named Veterinary Surgeon.

 

Key publications 

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