DNAJC14 Gene-Edited Pigs: Engineering Resistance to Classical Swine Fever

Classical Swine Fever virus (CSFV) is a highly contagious pestivirus of pigs that can cause severe outbreaks with high mortality, leading to trade restrictions and major economic losses. Although currently absent from the UK, CSFV remains endemic in several regions worldwide and continues to threaten global pig production and food security. While vaccines are available, eradication remains challenging due to limitations in disease surveillance and continued transmission within wild pig populations. Consequently, novel strategies such as precision genome editing could help reduce the substantial animal welfare and economic impacts associated with CSFV outbreaks.

The Breakthrough: Targeting a Host Dependency

Many viruses have a clever way of packing a lot of information into a small genetic blueprint. They produce large proteins called polyproteins, which can be cut into several smaller proteins that perform different functions. To function properly, these polyproteins rely on host-cell "molecular helpers" known as chaperones, which enable viruses to replicate and spread efficiently. The DNAJC14 gene encodes a chaperone protein involved in regulating protein complexes at cellular membranes. Originally identified as a host factor for replication of the pestivirus bovine viral diarrhoea virus (BVDV), DNAJC14 was subsequently shown in cultured cells to be essential for replication of both CSFV and BVDV, as knockout or substitution of a single amino acid prevented viral replication. These findings suggested that DNAJC14 editing could confer resistance to CSFV by disrupting a host factor essential for viral replication, highlighting the potential of host-directed gene editing to enhance disease resistance.

The Challenge: Producing CSFV-Resistant Pigs

The next step was to investigate whether this host factor could be safely edited in pigs and whether this would confer resistance to the virus. Researchers showed that a targeted edit to the pig DNAJC14 gene, both by introducing a specific amino acid substitution or knockout did not affect pig health. Furthermore, both editing options of DNAJC14 provided complete resistance to CSFV under controlled challenge conditions. In this study, CRISPR/Cas9 editing with a homology directed repair template was used in zygotes to generate pigs carrying the edited DNAJC14 allele. The effectiveness of the edit was first assessed in vitro, where primary cells derived from edited pigs did not support CSFV replication. This was followed by an in vivo CSFV challenge, in which edited adult pigs showed complete resistance with no detectable signs of infection, unlike wild-type control animals.

Engineering Biology DBTL Loop in action

This case study shows how engineering biology can support livestock health by identifying a host factor required for viral replication, engineering a precise genetic edit, and validating disease resistance in pigs.

• Design: Host genetic targets associated with CSFV susceptibility are identified using in vitro gene–function analyses, identifying a testable genome-editing strategy.
• Build: Genome-editing approaches and reproductive technologies are used to generate precisely edited porcine cells and pigs.
• Test: Edited pigs are evaluated using in vitro infection models and in vivo phenotyping to assess viral resistance and host immune responses.
• Learn: Experimental data are integrated to assess editing precision, scalability, and translational potential, while identifying potential effects on fitness for future refinement.

Impact and next steps

As related pestiviruses also affect cattle and sheep, the work raises the possibility that similar host-directed editing strategies could provide protection across livestock species. Supporting earlier findings, primary cells from the edited pigs also showed resistance BVDV. In a next step, scientists at the Roslin Institute, with funding from the BBSRC, are now exploring how editing the DNAJC14 gene affects sheep's resistance to Border Disease Virus (BDV), which causes the debilitating "hairy shaker syndrome" in infected animals.

Identifying host factors as editable targets for disease resistance for other diseases and species could help address the global challenge of livestock disease. Achieving this will require continued development of advanced genome-engineering tools and discovery pipelines to identify editable candidate genes in livestock. The Roslin Engineering Biology Hub supports these goals through integrated capabilities in target discovery, genome engineering, and livestock reproductive technologies.

A collaborative effort and advanced infrastructure

This research was carried out in collaboration with animal genetics company Genus Plc, alongside colleagues at the Animal and Plant Health Agency (APHA) and the University of Lübeck. The APHA pestivirus research team provided technical expertise, while the APHA animal sciences team supported the in vivo CSFV challenge studies and sample collection. The project was also supported by the Large Animal and Imaging Facility (LARIF) at the Roslin Institute, which provided:

• Precision embryo editing and founder generation
• Production and husbandry of gene-edited pigs
• Primary cell isolation and infection assays
• High-health animal facilities and monitoring

Animal welfare was central throughout the project, with all procedures conducted to the highest ethical and care standards in close collaboration with trained animal technicians and the Named Veterinary Surgeon.

Key publications

• Crooke et al. Trends in Biotechnology (2025) https://doi.org/10.1016/j.tibtech.2025.09.008
• Isken et al. Journal of Virology (2019) https://doi.org/10.1128/jvi.01714-18