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Several emerging pestiviruses have been reported lately, some of which have proved to cause disease. Recently, a new ovine pestivirus (OVPV), isolated from aborted lambs, with high genetic identity to classical swine fever virus (CSFV), has proved to induce reproductive disorders in pregnant ewes. OVPV also generated strong serological and molecular cross-reaction with CSFV. To assess the capacity of OVPV to infect swine, twelve piglets were infected either by intranasal or intramuscular route. Daily clinical evaluation and weekly samplings were performed to determine pathogenicity, viral replication and excretion and induction of immune response. Five weeks later, two pigs from each group were euthanized and tissue samples were collected to study viral replication and distribution. OVPV generated only mild clinical signs in the piglets, including wasting and polyarthritis. The virus was able to replicate, as shown by the RNA levels found in sera and swabs and persisted in tonsil for at least 5 weeks. Viral replication activated the innate and adaptive immunity, evidenced by the induction of interferon-alpha levels early after infection and cross-neutralizing antibodies against CSFV, including humoural response against CSFV E2 and Erns glycoproteins. Close antigenic relation between OVPV and CSFV genotype 2.3 was detected. To determine the OVPV protection against CSFV, the OVPV-infected pigs were challenged with a highly virulent strain. Strong clinical, virological and immunological protection was generated in the OVPV-infected pigs, in direct contrast with the infection control group. Our findings show, for the first time, the OVPV capacity to infect swine, activate immunity, and the robust protection conferred against CSFV. In addition, their genetic and antigenic similarities, the close relationship between both viruses, suggest their possible coevolution as two branches stemming from a shared origin at the same time in two different hosts. [ABSTRACT FROM AUTHOR]

Influenza D virus (IDV) was first reported in 2011 in swine in Oklahoma and consequently found in cattle, sheep, and goats across North America and Eurasia. Cattle have been proposed as the natural reservoir. In this study, we developed and validated a MAb‐based competitive ELISA for the detection of antibodies against IDV. Thirty‐one hybridomas specific to IDV were generated using Balb/C mice immunised with purified IDV/Swine/Italy/199724‐3/2015. The specificity of MAbs was determined by comparing their reactivity with the homologous and other influenza A viruses along with additional bovine and swine viruses. A solid‐phase competitive ELISA (IDV‐cELISA) was set up using the partially purified antigen coated to the plate and incubation of two serum dilutions (1/10 and 1/20) followed by addition of a peroxidase‐conjugated MAb as competitor, which had shown wide intratype cross‐reactivity and positivity in HI. To evaluate the diagnostic performances of IDV‐cELISA, we used 884 sera (414 negative and 470 positive) from different species. ROC analyses were performed to enable the selection of best cut‐off value and estimation of diagnostic specificity and sensitivity. The agreement between IDV‐cELISA and HI test was assessed by Cohen's kappa value (κ). The κ analysis showed an almost perfect agreement (κ = 0.93; 95%CI −0.899 to 0.961) between HI test and IDV‐cELISA. ROC analysis showed that IDV‐cELISA was accurate with an area under the curve (AUC) = 0.999, 95% CI 0.993–1.000). A cut‐off value of 65% was selected with Se and Sp values of 99.35 (95% CI 98.1–99.9) and 98.75 (95% CI 97.1–99.6). These results proved excellent diagnostic performances of IDV‐cELISA, which compared to HI presented major advantages, such as suitability for automation, low dependence on individual skills, spectrophotometric reading, and easy interpretation of the results. This assay can be exploited to detect anti‐IDV antibodies in different animal species. [ABSTRACT FROM AUTHOR]