Interferon cures cells lytically and persistently infected with African swine fever virus in vitro

Human interferon alpha (IFN-alpha) and interferon gamma (IFN-gamma) inhibit African swine fever (ASF) virus replication in Vero cells. IFN-alpha and IFN-gamma exert a synergistic inhibition. Human tumor necrosis factor (TNF) does not inhibit ASF virus replication in this cell line, but in combination with IFNs it has antiviral enhancing activity. Analysis of the mechanism of inhibition suggests that the action of these cytokines blocks a step that comes prior to DNA replication. The 2'-5' A synthetase activity is induced in Vero cells by treatment with these cytokines and is activated after ASF virus infection. More interesting is the finding that continuous treatment with IFN-alpha cures Vero cells from lytic and persistent infections with ASF virus. A potential application of IFN for the treatment of animals carrying the virus is suggested.