Study tests ELISA approach to separate ovine pestivirus from CSF

A newly published study in Frontiers in Veterinary Science describes an E2-based indirect ELISA strategy aimed at a practical diagnostic blind spot in swine medicine: telling apart antibody responses to ovine Italy pestivirus, or ovIT PeV, from those to classical swine fever virus in pigs. The paper, published June 16, 2026, comes from investigators at IZSLER, IZSUM, and the WOAH Reference Laboratory for Classical Swine Fever at IRTA-CReSA, among others. (frontiersin.org)

The backdrop is a familiar one for veterinary diagnosticians. Classical swine fever remains a high-consequence, internationally reportable disease of pigs and wild boar, and serologic surveillance plays an important role, particularly at the herd level and in eradication settings. But CSF serology has long been limited by cross-reactivity with other pestiviruses. WOAH and EU guidance both note that antibodies generated by ruminant pestiviruses can produce misleading serologic results, which is why positive ELISA findings often require confirmatory testing, including comparative virus neutralization approaches. (oie.int)

That concern has become more relevant since ovIT PeV was identified in 2017 from aborted lamb fetuses and found to be genetically distinct, yet closely related phylogenetically to CSFV. The new Frontiers paper notes that experimental infections have shown pigs are susceptible to this ovine pestivirus and can mount a strong early immune response that cross-reacts in CSF serology. In other words, a pig can look seropositive for CSF without actually having been exposed to CSFV, a scenario with obvious implications for outbreak investigation, movement controls, and trade-sensitive surveillance programs. (frontiersin.org)

To tackle that, the researchers expressed recombinant E2 proteins from both ovIT PeV and CSFV and built two parallel indirect ELISAs. They evaluated 339 pestivirus-antibody-negative field sera, plus sera from experimentally infected pigs. Using a 1:50 serum dilution, they set an OD cut-off of 0.2 for both assays. The important finding was not that cross-reactivity disappeared, because it didn’t: sera from CSFV-infected pigs also reacted in the ovIT PeV assay, and vice versa. Instead, the discriminatory value came from comparing endpoint titers across the two assays. All samples with a titer ratio above 1 came from CSFV-infected pigs, while samples with a ratio below 1 came from ovIT PeV-infected pigs; homologous titers were significantly higher in each group, with p < 0.001. Virus neutralization results tracked in the same direction. (frontiersin.org)

The study fits with a broader diagnostic trend in pestivirus work: moving from simple binary serology toward differential platforms that use antigen selection, paired assays, or confirmatory neutralization to separate closely related infections. Prior literature has shown how E2-based assays can vary in cross-reactivity across CSFV genotypes and how confirmatory strategies are often needed when pestiviruses overlap serologically. This new work extends that logic to ovIT PeV, which is especially relevant because natural pig infections haven’t been reported so far, but experimental susceptibility means surveillance systems still need a way to interpret suspicious serology correctly. (frontiersin.org)

There doesn’t appear to be a separate institutional press release or broad public industry reaction yet, but the paper’s author list itself is notable. It includes scientists from national veterinary institutes in Italy, the WOAH CSF reference laboratory in Spain, and the Friedrich-Loeffler-Institut in Germany, suggesting the work is grounded in reference-lab diagnostic priorities rather than being purely academic. The authors are also measured about the result: they say the paired iELISAs can provide an initial indication of ovIT PeV infection, but should be followed by additional diagnostic testing, and they call for broader specificity testing against a wider range of porcine and ruminant pestiviruses. (frontiersin.org)

Why it matters: For veterinary professionals, especially diagnosticians, swine veterinarians, and animal health officials, this is less about a new commercial test and more about a smarter interpretation framework. In a disease like CSF, where a false signal can trigger major regulatory and economic consequences, better serologic discrimination matters. A paired-antigen, titer-comparison approach could help labs triage suspect sera more effectively, decide when to escalate to neutralization or molecular testing, and avoid over-calling CSF based on cross-reactive antibodies alone. It also reinforces a broader lesson for practice: serology remains useful for herd surveillance, but in pestivirus-heavy epidemiologic contexts, it works best as part of a layered diagnostic algorithm, not as a standalone answer. (oie.int)

What to watch: The next milestones are external validation, inclusion of additional pestiviruses such as BVDV and BDV in specificity panels, and any movement by reference laboratories or surveillance programs to test this approach alongside existing CSF confirmatory workflows. If those studies hold up, the method could become a useful niche tool for resolving ambiguous CSF serology before it turns into a bigger regulatory event. (frontiersin.org)