Comparative Analysis of Tunisian Sheep-like Virus, Bungowannah Virus and Border Disease Virus Infection in the Porcine Host

Abstract

Apart from the established pestivirus species Pestivirus A to Pestivirus K novel species emerged. Pigs represent not only hosts for porcine pestiviruses, but are also susceptible to bovine viral diarrhea virus, border disease virus (BDV) and other ruminant pestiviruses. The present study focused on the characterization of the ovine Tunisian sheep-like virus (TSV) as well as Bungowannah virus (BuPV) and BDV strain Frijters, which were isolated from pigs. For this purpose, we performed genetic characterization based on complete coding sequences, studies on virus replication in cell culture and in domestic pigs, and cross-neutralization assays using experimentally derived sera. TSV forms a distinct phylogenetic group more closely related to Pestivirus C (classical swine fever virus, CSFV) than to Pestivirus D (BDV). In contrast to BDV and BuPV, TSV replicates by far more efficiently on ovine than on porcine cells. Nevertheless, pigs were susceptible to TSV. As a consequence of close antigenic relatedness of TSV to CSFV, cross-reactivity was detected in CSFV-specific antibody assays. In conclusion, TSV is genetically closely related to CSFV and can replicate in domestic pigs. Due to close antigenic relatedness, field infections of pigs with TSV and other ruminant pestiviruses can interfere with serological diagnosis of classical swine fever.

Isolation and Molecular Evidence of Tunisian Sheep-like Pestivirus (Pestivirus N) in Persistently Infected Sheep in Northern Italy, 2023

“…This study confirmed that TSV replicates efficiently in LKi cells, as previously demonstrated by the fact that this virus is well adapted to ovine cells [ 8 ]. Although less efficient, TSV was also grown on porcine ST and bovine MDBK cells (only for serum samples obtained in November 2023).…”

“…Phylogenetic analysis showed that these strains had 100% nucleotide identity with the 124910/77-2023 strain. The three TSV isolates, Aydin-like pestivirus strains, and novel ovIT PeVs formed three distinct groups located between CSFV and BDV [ 8 ]. In addition, the phylogenetic analysis showed that TSV forms two distinct groups and is more closely related to CSFV than BDV or other ruminant pestiviruses [ 6 , 7 , 8 ].…”

“…Although TSV is related to CSFV, Meyer et al, 2021 [ 8 ] showed that experimental infection in pigs did not result in clinical signs. However, the TSV genome was detected in the blood at 5, 7, and 14 dpi, confirming that TSV could replicate in domestic pigs under experimental conditions.…”

“…The Tunisian sheep-like pestivirus (TSV, Pestivirus N ) was first isolated from batches of a contaminated sheep pox vaccine in Tunisia and represents an additional ovine pestivirus that is genetically and antigenically more closely related to CSFV than to the border disease virus (BDV, Pestivirus ovis ) [ 6 , 7 , 8 ]. Subsequently, TSV was detected in sheep in France and goats and sheep in Italy [ 9 , 10 ].…”

“…Infection of pregnant ewes with TSV resulted in clinical signs typically associated with border disease, including high rates of abortion, stillbirth, and birth of weak and hairy-shaker lambs [ 6 ]. Recently, considering the close relationship between TSV and CSFV, pigs were found to be susceptible to TSV; however, they did not show any clinical sign after horizontal transmission [ 8 ].…”