How Recombinant Proteins Are Unlocking the Secrets of African Swine Fever
In the high-stakes battle against one of the most devastating animal diseases, scientists are wielding a powerful tool that's invisible to the naked eye.
African Swine Fever (ASF) is a highly contagious viral disease that causes near-100% mortality in domestic pigs and wild boar, triggering enormous economic losses and threatening global food security. Since its arrival in Georgia in 2007, the virus has swept across Europe and Asia, reaching the Dominican Republic and Haiti in 2021 and placing the entire American continent on high alert.
Mortality Rate in Domestic Pigs
Countries Affected Worldwide
Commercial Treatments Available
With no commercially available treatment and traditional vaccine approaches falling short, researchers have turned to advanced genetic engineering for solutions. At the forefront of this fight are recombinant proteins – artificially created viral proteins that serve as both precision diagnostics and promising vaccine candidates, offering new hope in controlling this relentless disease.
Recombinant proteins are molecular replicas of viral components produced not by the virus itself, but by engineered microorganisms in laboratory settings. Scientists isolate the gene that codes for a specific viral protein and insert it into host cells like E. coli bacteria or insect cells. These cellular factories then mass-produce the protein, providing researchers with a pure, safe, and consistent supply without ever handling the dangerous live virus.
The ASF virus (ASFV) is remarkably complex – a large, double-stranded DNA virus with a genome encoding 150-200 proteins. This complexity has hindered traditional vaccine development and made accurate diagnosis challenging. Recombinant proteins allow scientists to:
Scientists identify and isolate the gene coding for a specific ASFV protein.
The gene is inserted into a plasmid vector for delivery into host cells.
The engineered plasmid is introduced into host cells like E. coli or insect cells.
Host cells are induced to produce the recombinant protein in large quantities.
The recombinant protein is extracted and purified from the host cells.
The purified protein is used for diagnostics, vaccine development, or research.
| Protein Name | Gene | Function & Application | Expression System |
|---|---|---|---|
| p30 | CP204L | Early expressed, highly antigenic; used in serological diagnostics and subunit vaccines 6 8 | E. coli, insect larvae 2 6 |
| p72 | B646L | Major capsid protein; used for genotyping and antibody detection 3 7 | E. coli 3 |
| p54 | E183L | Involved in virus entry; often combined with p30 in vaccine candidates 8 | E. coli 8 |
| pEP153R | EP153R | C-type lectin; potential DIVA (Differentiation of Infected from Vaccinated Animals) antigen | E. coli, mammalian cells |
| eGFP | - | Reporter gene; inserted into vaccine strains for tracking and DIVA purposes | E. coli, mammalian cells |
A 2025 study exemplifies the recombinant protein approach, developing an indirect ELISA (enzyme-linked immunosorbent assay) using recombinant p30 as the sole antigen 6 . The research followed these key steps:
Researchers synthesized the gene sequence (CP204L) coding for the p30 protein and inserted it into a specialized plasmid vector.
The engineered plasmid was introduced into E. coli bacteria, which were induced to produce the recombinant p30 protein.
The bacterial cells were broken open, and the recombinant p30 protein was purified using affinity chromatography.
The purified p30 was used to coat ELISA plates and validated using 69 well-characterized swine serum samples 6 .
The p30-based ELISA demonstrated outstanding performance, offering a rapid, cost-effective method for large-scale ASF surveillance 6 :
| Performance Metric | Result |
|---|---|
| Sensitivity | 95.6% |
| Specificity | 92.3% |
| Kappa Index (κ) | 0.836 (near-perfect agreement) |
| Inter-assay Variability | 4.27% |
| Intra-assay Variability | 4.85% |
This experiment confirmed that p30 alone could serve as a highly effective antigen for ASF detection, simplifying test production while maintaining accuracy. The excellent detection capability – identifying antibodies even in sera diluted up to 1:100 – highlights the test's potential for sensitive surveillance programs in ASF-free regions and outbreak zones alike 6 .
The promising immunogenic properties of proteins like p30 and p54 have propelled them into vaccine research. Scientists are exploring creative ways to enhance their ability to stimulate protective immunity:
Researchers have engineered recombinant proteins that combine p30 and p54 with molecular adjuvants like flagellin (a TLR5 activator) to boost immune responses 4 . One such construct, p30-FliCΔD2D3, elicited strong p30-specific antibody and T-cell responses in mice 4 .
Another innovative approach fuses p30 and modified p54 with the bacterial lipoprotein OprI, which activates TLR2 signaling. When tested in mice, these fusion proteins (OPM and OPMT) stimulated dendritic cell maturation and elicited antigen-specific IgG antibodies and proinflammatory cytokines crucial for antiviral defense. Importantly, sera from vaccinated mice neutralized more than 86% of ASFV in vitro, a promising result for a subunit vaccine candidate 8 .
Despite these advances, significant challenges remain in the application of recombinant proteins for ASF control. The complexity of the virus – with its numerous proteins and sophisticated immune evasion strategies – means that single-protein subunit vaccines often provide only partial protection 7 8 . Researchers are addressing this by:
Exploring combinations of several immunogenic proteins to enhance protection.
Developing better delivery mechanisms and more potent adjuvants.
Creating tests that distinguish vaccinated animals from infected ones .
The recent emergence of novel recombinant genotype I/II strains in China and Vietnam, along with vaccine-like variants detected in the field, further underscores the need for vigilant surveillance and adaptable tools 1 9 . Recombinant protein-based tests will be essential for monitoring these evolving viral populations.
Recombinant proteins have revolutionized our approach to African Swine Fever, transforming once-risky virus research into a precise, controlled science conducted in test tubes and bioreactors. From enabling rapid diagnosis through tests like the p30-based ELISA to forming the foundation of next-generation subunit vaccines, these molecular tools have become indispensable in the global effort to control this devastating disease.
While there is no silver bullet yet, the continuous refinement of recombinant protein technology represents our best hope for eventually conquering ASF. Our ability to manipulate these viral building blocks brings us closer than ever to developing the comprehensive control strategies needed to protect global swine populations and ensure food security for future generations.