Antiviral effect of recombinant equine interferon-γ on several equine viruses

Recombinant equine interferon-γ (reIFN-γ) was prepared using a baculovirus expression system and its antiviral activity was investigated using several equine viruses. The reIFN-γ suppressed the replication of all equine viruses used in the present experiment in horse cell cultures, but did not affect the growth of host cells at concentrations of less than 1000 u/ml. A strong antiviral effect was observed, especially against RNA viruses. Equine picornavirus, equine rhinovirus and equine arteritis virus could not be propagated at all in 100 u/ml reIFN-γ when 100 TCID50 of infective viruses was inoculated to cultivated horse cells. DNA viruses, equine herpesvirus types 1, 2, 3 and 4 and equine adenovirus, were less sensitive to reIFN-γ but their growth became less than 1/100 in the cells treated with 100 u/ml reIFN-γ compared to untreated cells. The antiviral effects were decreased in the cells of heterologous species and more than 1000 u/ml reIFN-γ was required to induce an antiviral effect.