IFNB1 and infection: (b) Upon interaction of a partially neutralized virion with a host target cell, the IFN-β domain anchored to the surface of the virion is predicted to trigger interferon-α/β receptor (IFNAR) signaling before host cell infection, such that the virion will only infect host cells with previously upregulated type I interferon (IFN-I) antiviral defenses.