Engineering pigs that are genetically resistant to the Porcine reproductive and respiratory syndrome (PRRS)

Background

Porcine reproductive and respiratory syndrome (PRRS) is considered the most costly infectious disease affecting pigs worldwide. It has a major economic and welfare impact on pig farming.

PRRS is estimated to cause annual losses of over £1.2 billion to pig industries in Europe and the United States of America.

Young piglets and pregnant sows are especially affected. 

When piglets become infected after birth, up to 80% may die as a result of PRRS virus infection. 

Infected pregnant sows often abort or give birth to stillborn piglets. Piglets that survive pregnancy frequently develop severe respiratory problems, and many die within the first weeks of life.

Because of its high mortality rates and economic cost, PRRS remains a top priority for pig health research and disease control. Improving prevention, management, and vaccination strategies is critical to reducing its global impact on pig farming.

At LARIF

This project showcases the advanced research supported by the Large Animal Research and Imaging Facility (LARIF). It combines cutting-edge laboratory science with specialist large animal facilities to tackle major livestock diseases.

At the Roslin Institute, researchers develop and refine advanced genome-editing techniques in the laboratory. Edited embryos are then implanted into female livestock at LARIF, where expert farm staff and scientists work together to support pregnancies and deliver healthy offspring in specialist facilities.

Using this approach, researchers have successfully produced pigs that are resistant to PRRS.

The syndrome is caused by a virus that infects pigs by attaching to a receptor on the surface of their cells called CD163. The research team precisely edited the pig genome at a single point so that animals no longer produce the specific part of the CD163 protein that the virus needs to establish infection.

The gene-edited pigs show no detectable differences in:

• health
• wellbeing
• production performance.

This demonstrates how precise gene editing can improve disease resistance while maintaining normal animal welfare and productivity.

The work highlights the potential of gene editing to protect livestock from major diseases, reduce economic losses, and improve animal welfare - offering a promising direction for the future of sustainable farming.

Impact

Porcine reproductive and respiratory syndrome (PRRS) is the costliest disease affecting pig industries in Europe and North America. 

This work has the potential to support:

• pig breeders
• farmers
• the full supply chain of pig products
• consumers, through more stable pricing and supply.

A direct outcome of the research is a patent for PRRS-resistant gene-edited pigs, which has been licensed to a major pig breeding company.

Regulatory approval for the sale of meat from these pigs has already been granted in:

• Colombia
• Brazil
• Dominican Republic
• United States

Applications in other regions are still in progress.

By preventing a highly damaging disease, this innovation can:

• improve the sustainability of pig farming
• lower production costs and potentially reduce prices
• significantly enhance the welfare of pigs and piglets by avoiding severe illness and mortality

The gene-editing methods developed through this work open the door to tackling other major diseases in livestock. 

The underlying techniques provide a foundation for future advances in large-animal health and sustainable agriculture.

Publications