Porcine interferon-gamma protects swine from foot-and-mouth disease virus (FMDV)

Porcine interferon-gamma (PoIFN-γ) fused with glutathione S-transferase (GST) was expressed in Escherichia coli BL₂₁. Twenty 6-week-old piglets were randomly assigned to four groups. Pigs in groups 1-3 were pretreated with 30 mg, 20 mg, and 10 mg recombinant PoIFN-γ (rPoIFN-γ), respectively. Pigs in group 4 (control) were pretreated with GST expressed by the empty plasmid. At 48 h postinoculation (hpi), all swine were challenged with FMDV (serotype O). Pigs pretreated with 30 mg rPoIFN-γ were completely protected from virulent FMDV attack. Pigs given 20 mg rPoIFN-γ achieved partial protection, and the unprotected piglets showed clinical signs from 68 h postchallenge (hpc). Although 10 mg rPoIFN-γ did not confer protection against FMDV, the pigs pretreated with this dose of rPoIFN-γ presented clinical signs from 35 hpc, which was later than the control group (14 hpc). These results indicate that PoIFN-γ can protect swine against attack from FMDV or delay the appearance of clinical signs; the effect is dose dependent.