Test developed in Spain simultaneously detects African swine fever and classical swine fever viruses

Classical swine fever (CSF), one of the most important animal diseases, remains a challenge for disease control. it is caused by the CSF virus (CSF), a (+) single-stranded RNA virus and a member of the genus Pestivirus. CSF control strategies are based on rapid diagnostics, primarily CSF antibody ELISA tests, and molecular detection of viral RNA using real-time RT-PCR (RT-qPCR).

African swine fever ( ASF ) is a contagious infectious disease of domestic pigs and wild boars with significant impact on animal welfare and pig production. Infected animals may exhibit a wide range of clinical syndromes depending on the virulence of the virus strain and host characteristics.

Clinically, several forms of the disease are distinguished: an acute form, which correlates with hemorrhagic fever and typical symptoms of ASF, with a high mortality rate (up to 95–100%); a subacute form, which manifests itself with similar, although less pronounced, signs with those in acute forms, and has a mortality rate of 30–70%; and a chronic form of the disease with nonspecific symptoms that last for months and do not resemble typical symptoms of ASF.

Access to highly sensitive diagnostic tests is therefore critical for disease control. A combination of direct antigen detection and specific antibody methods is particularly relevant for ASF monitoring. Virus detection can be performed by virus isolation, fluorescent antibody testing, PCR or ELISA.

Simultaneous detection of African swine fever and classical swine fever viruses

The increasing prevalence of African swine fever in recent years and the presence of subclinical forms of classical swine fever in endemic countries suggest that the possibility of coinfection with ASFV and CSFV in pigs cannot be excluded in areas where both diseases are common. 

Therefore, rapid and reliable diagnosis using molecular testing is critical to timely control measures to prevent the spread of these devastating swine diseases. 

A study by Lilianna Ganges, Liani Coronado, Adriana Muñoz-Aguilera, Miao Miao Wang, Ivan Muñoz, Cristina Riquelme, Saray Heredia from IRTA-CReSA and Carmina Gallardo from the National Institute of Agricultural and Food Research and Technology (INIA) examined the simultaneous detection of classical and African swine fever viruses by real-time PCR in pigs infected with both diseases.

"We combined the two most validated PCR assays for the detection of CSFV and ASFV in a single reaction tube. Combining two tests for the detection of two target nucleic acids did not affect the analytical sensitivity, and the duplex RT-PCR assay was comparable to standard molecular methods." 

The test demonstrated high repeatability and reproducibility with a coefficient of variation of less than 2% and excellent performance in clinical samples. The duplex assay "has great potential to become a reliable diagnostic tool for the rapid and reliable detection and differentiation of classical swine fever virus and African swine fever virus in areas where both viruses may circulate."