The new emerging ovine pestivirus can infect pigs and confers strong protection against classical swine fever virus

Abstract

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.

Development of a new loop-mediated isothermal amplification test for the sensitive, rapid, and economic detection of different genotypes of Classical swine fever virus

“…It is worth highlighting the capacity of this virus to rapidly generate antibodies in swine after infection ( Wang et al., 2020b ), which in any case would favor reducing the circulating viral load and in turn reducing the possibility of OVPV cross-reactivity with test developed here. In addition, it’s unlikely that the cross-reaction of the LAMP test with OVPV would translate to a field setting, since the only study regarding experimental infection of pigs with OVPV showed that the viral RNA load detected in pigs after infection is much lower than that used for testing of the LAMP assay in the present study ( Bohórquez et al., 2021 ).…”

Proposed Update to the Taxonomy of Pestiviruses: Eight Additional Species within the Genus Pestivirus, Family Flaviviridae

“…The genetic and antigenic similarity of CSFV, TSV, and ovIT isolates complicates the demarcation of species in the genus Pestivirus. A close genetic and antigenic relationship between the ovIT isolates (Pestivirus O) and CSFV (Pestivirus C) has been recently reported and may cause problems in CSF molecular and serological diagnosis if the ovine pestiviruses are ever shown to be able to infect porcine hosts under natural conditions [50,51]. Genetic analysis based on p-distances was not suited to demarcate the species Pestivirus N and Pestivirus O, which are closely related to each other and to CSFV (Pestivirus C) as calculated distances lie in a range that do not show a clear affiliation.…”

“…Furthermore, a clear discrimination to CSFV (Pestivirus C) might become challenging if viruses similar to TSV (Pestivirus N) and ovIT PeV (Pestivirus O) are found to cross the species barrier and efficiently infect and replicate in porcine hosts under natural conditions. In this context, it is important to emphasize that, despite close genetic and antigenic relatedness of CSFV (Pestivirus C), TSV (Pestivirus N), and ovIT PeV (Pestivirus O), clear differences exist in host specificity and clinical disease induced by both ruminant pestiviruses in comparison to CSFV (Pestivirus C) [39,51]. TSV (Pestivirus N) was discovered in 1995 and since that time, no natural infections have been reported in porcine hosts.…”

“…In addition, replication of TSV (Pestivirus N) on porcine cells was demonstrated to be rather inefficient in vitro. Moreover, these ruminant pestiviruses were either not able to induce disease (in the case of TSV) or induced only mild, unspecific clinical signs and pathological alterations (in the case of ovIT isolates) that resemble the outcome of horizontal infections of pigs with other ruminant pestiviruses, e.g., BVDV-1 (Pestivirus A) and BDV (Pestivirus D) [39,51].…”

Removal of the E rns RNase Activity and of the 3′ Untranslated Region Polyuridine Insertion in a Low-Virulence Classical Swine Fever Virus Triggers a Cytokine Storm and Lethal Disease

“…In addition, the virulence of the double mutant virus was also evaluated in six 3-week-old pigs from Pestivirus -free sows (numbered 20 to 25), as in previous studies ( 43 , 44 ). The six pigs were inoculated intranasally with 2.5 × 10 4 TCID 50 s of vPdR-H 30 K-5U.…”