Effects of recombinant interferon-tau on ovine lentivirus replication

As a pregnancy recognition signal, sheep trophoblast cells secrete a type I interferon, ovine interferon-tau (OvIFN-tau), which has potent antiviral activity. We studied the effects of a recombinant protein (rOv-IFN-tau) on the replication of ovine lentivirus (OvLV) in goat synovial membrane cells. The amount of provirus DNA, as measured by polymerase chain reaction (PCR), the virus titers, and the number of OvLV-induced syncytia were 76.5%, 82%, and 95%, respectively, lower in cultures treated with rOv-IFN-tau than in placebo-treated controls (p < 0.01). rOv-IFN-tau also reduced OvLV reverse transcriptase activity and protected cells from OvLV-induced cell lysis, but the effect was less dramatic. The antiviral activity increased with the concentration up to a maximum with 256 antiviral units of rOv-IFN-tau per ml.