Rapid On-Farm Diagnostic Technologies for African Swine Fever

African swine fever (ASF) remains one of the most significant transboundary diseases affecting pig populations, making rapid diagnosis essential for timely disease control and surveillance. While laboratory-based diagnostic methods provide high analytical sensitivity, they often require specialized equipment and trained personnel. In field settings, veterinarians frequently need diagnostic tools that can deliver reliable results quickly without depending on sophisticated laboratory infrastructure. 

Recent advances in rapid on-farm diagnostic technologies have expanded the options available for point-of-care detection. These methods are designed to shorten the time between sample collection and diagnosis, supporting faster decision-making during suspected outbreaks, routine surveillance, and animal movement screening. 

Isothermal Amplification: Bringing Molecular Detection to the Field 

Unlike conventional molecular techniques that require thermal cycling, isothermal amplification methods operate at a constant temperature, making them more suitable for field deployment. 

Recombinase Polymerase Amplification (RPA) and Recombinase-Aided Amplification (RAA) are among the most widely explored rapid molecular techniques for ASF detection. Several assays targeting the B646L gene have demonstrated detection within 10–15 minutes, with high analytical sensitivity^1,2,3. Portable real-time RAA has also been developed to target the EP402R gene, allowing detection of as few as 10 copies/reaction while simultaneously differentiating CD2V gene deletions, an important feature for specific diagnostic applications¹. 

To further simplify field testing, RPA has been combined with lateral flow dipsticks, nucleic acid test strips, and quantum dot microspheres, enabling rapid visual interpretation while maintaining satisfactory detection performance^1,4. 

Another important platform is Loop-Mediated Isothermal Amplification (LAMP), which amplifies viral nucleic acids using multiple primers under constant temperature conditions. LAMP assays targeting K78R, B646L, 9GL, and TPII genes have demonstrated low detection limits suitable for ASF diagnosis^1,5,6,7. Additional innovations, including ladder-shaped melting temperature isothermal amplification, carbon nanodot-based fluorescent biosensors, and Hive-Chip visual detection systems, have further enhanced the practicality of LAMP for field applications^1,8,9. 

Emerging Technologies Enhance Point-of-Care Testing 

The integration of CRISPR/Cas technology with RPA and LAMP has further strengthened rapid ASF diagnosis. These systems detect target sequences through Cas12a or Cas13a-mediated cleavage, allowing results to be visualized using fluorescence or lateral flow strips. Depending on the platform, detection limits range from 1–7 copies/μL for LAMP-based assays and 10–20 copies/μL for RPA/RAA-based assays^1,10. Compact fluorescence-based point-of-care devices have also been developed to provide automated, portable, and relatively inexpensive on-site detection¹¹. 

Other promising technologies continue to expand the diagnostic toolbox. Strand Recombinase Catalytic Amplification (SRCA) has demonstrated suitability for on-site testing of clinical samples (67), while Cross-Priming Amplification (CPA) has been successfully applied to blood and serum samples for rapid detection. Optical detection methods, sandwich colloidal gold test strips targeting the P30 protein, and biosensor-based platforms further contribute to rapid visual diagnosis under field conditions. 

Rapid On-Farm Technologies at a Glance 

Key Takeaway 

Rapid on-farm diagnostic technologies are expanding the diagnostic options available to veterinarians managing African swine fever in the field. Isothermal amplification methods, CRISPR-based assays, and biosensor platforms provide practical alternatives when rapid decision-making is required and laboratory access is limited. Each technology offers distinct operational advantages, and selecting the most appropriate method depends on the testing objective, available resources, and field conditions. Used appropriately, these rapid diagnostic tools can strengthen surveillance, support outbreak investigations, and complement laboratory confirmation as part of an effective ASF control strategy. 

References 

1. Hu Z, Tian X, Lai R, Wang X, Li X. Current detection methods of African swine fever virus. Frontiers in Veterinary Science. 2023 Dec 8;10:1289676. https://www.frontiersin.org/journals/veterinary-science/articles/10.3389/fvets.2023.1289676/full 

2. Wang J, Wang J, Geng Y, Yuan W. A recombinase polymerase amplification-based assay for rapid detection of African swine fever virus. Canadian Journal of Veterinary Research. 2017 Oct 1;81(4):308-12. https://pmc.ncbi.nlm.nih.gov/articles/PMC5644446/pdf/cjvr_04_308.pdf 

3. Fan X, Li L, Zhao Y, Liu Y, Liu C, Wang Q, Dong Y, Wang S, Chi T, Song F, Sun C. Clinical validation of two recombinase-based isothermal amplification assays (RPA/RAA) for the rapid detection of African swine fever virus. Frontiers in Microbiology. 2020 Jul 21;11:1696. https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2020.01696/pdf 

4. Li JS, Hao YZ, Hou ML, Zhang X, Zhang XG, Cao YX, Li JM, Ma J, Zhou ZX. Development of a recombinase-aided amplification combined with lateral flow dipstick assay for the rapid detection of the African swine fever virus. Biomedical and Environmental Sciences. 2022 Feb 1;35(2):133-40. https://www.besjournal.com/fileSWYXYHJKX/journal/article/swyxyhjkx/2022/2/PDF/21067.pdf 

5. Wang Y, Dai J, Liu Y, Yang J, Hou Q, Ou Y, Ding Y, Ma B, Chen H, Li M, Sun Y. Development of a potential penside colorimetric LAMP assay using neutral red for detection of African swine fever virus. Frontiers in microbiology. 2021 Apr 23;12:609821. https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2021.609821/pdf 

6. Wang S, Shen H, Lin Q, Huang J, Zhang C, Liu Z, Sun M, Zhang J, Liao M, Li Y, Zhang J. Development of a cleaved probe-based loop-mediated isothermal amplification assay for rapid detection of African swine fever virus. Frontiers in Cellular and Infection Microbiology. 2022 May 26;12:884430. https://www.frontiersin.org/journals/cellular-and-infection-microbiology/articles/10.3389/fcimb.2022.884430/pdf 

7. Mee PT, Wong S, O’Riley KJ, da Conceição F, Bendita da Costa Jong J, Phillips DE, Rodoni BC, Rawlin GT, Lynch SE. Field verification of an African swine fever virus loop-mediated isothermal amplification (LAMP) assay during an outbreak in timor-leste. Viruses. 2020 Dec 15;12(12):1444. https://www.mdpi.com/1999-4915/12/12/1444 

8. Cao G, Qiu Y, Long K, Xiong Y, MeimeiShi, JunYang, Li Y, Nie F, Huo D, Hou C. Carbon nanodots combined with loop-mediated isothermal amplification (LAMP) for detection of African swine fever virus (ASFV). Microchimica Acta. 2022 Sep;189(9):342. https://pmc.ncbi.nlm.nih.gov/articles/PMC9396581/pdf/604_2022_Article_5390.pdf 

9. Zhu YS, Shao N, Chen JW, Qi WB, Li Y, Liu P, Chen YJ, Bian SY, Zhang Y, Tao SC. Multiplex and visual detection of African Swine Fever Virus (ASFV) based on Hive-Chip and direct loop-mediated isothermal amplification. Analytica Chimica Acta. 2020 Dec 15;1140:30-40. https://pmc.ncbi.nlm.nih.gov/articles/PMC7542229/pdf/main.pdf 

10. Qian S, Chen Y, Peng C, Wang X, Wu H, Che Y, Wang H, Xu J, Wu J. Dipstick-based rapid nucleic acids purification and CRISPR/Cas12a-mediated isothermal amplification for visual detection of African swine fever virus. Talanta. 2022 May 15;242:123294. https://papers.ssrn.com/sol3/Delivery.cfm?abstractid=3981309 

11. He Q, Yu D, Bao M, Korensky G, Chen J, Shin M, Kim J, Park M, Qin P, Du K. High-throughput and all-solution phase African Swine Fever Virus (ASFV) detection using CRISPR-Cas12a and fluorescence based point-of-care system. Biosensors and Bioelectronics. 2020 Apr 15;154:112068. https://www.biorxiv.org/content/biorxiv/early/2019/10/01/788489.full.pdf