Recombinant ovine interferon-tau (roIFN-τ) modulates lymphocyte subsets, and ovine lentivirus (OvLV)-induced lung pathology

We evaluated the role of roIFN-τ, a type I IFN, as a modulator of blood mononuclear cell (BMC) phenotypes and lung pathology in non-infected, and OvLV-infected lambs. IFN-τ, the ovine pregnancy recognition signal, has antiviral activity against OvLV and HIV and is less toxic. Similar to HJV, OvLV induces lymphoid interstitial pneumonia. 24 lambs were divided into 4 groups: i) Control; ii) Non-infected+10⁶ antiviral units (AVU) roIFN-τ/kg/day s.c.; iii) 10⁶ TCID₅₀ OvLV intratracheal + placebo; iv) 10⁶ TCID₅₀ OvLV intratracheal +10⁶ AVU roIFN-τ/kg/day s.c. BMCs were labeled every week (0-12) with monoclonal antibodies against CD45, CD4, CD8, γδ, MHC II, CD44 and L-selectin (LS) for flow cytometry. The results were compared within (P≤0.001), and between the groups (P≤0.01) with the Student-Newman-Keuls test. Individually, roIFN-τ and OvLV significantly increased the proportions of all the cell markers except MHC II⁺ cells in the later. OvLV-infected, roIFN-τ-treated lambs showed higher numbers of CD8⁺, CD4⁺ and γδ⁺ cells than the non-treated, infected lambs. No significant increase was noticed in the infected, treated group for CD44⁺ and LS⁺ cells, Histopathology showed lack of lesions in the lungs of roIFN-τ-treated, OvLV-infected as compared to non-treated, infected group. Enhanced cytotoxic cell numbers and a lack of increase in CD44⁺ and LS⁺ cells explain the lack of lung pathology in the roIFN-τ-treated, OvLV-infected lambs.