Role of Infection in Viral Interference: I. Inhibition of Lethal Infections in Chick Embryos Preinfected with Influenza Viruses

Introduction  The use of both infective and inactivated viruses as interfering agents¹ and their use in the production of interferons is well known.² Since the discovery of interferon³ and the postulation that it is the chemical intermediary of interference,^4,5,2 the problem as to whether it can quantitatively account for all the interfering activity even in situations in which it is admittedly operative remains.² One such situation is viral interference produced by infective virus in cell cultures or in the intact host.In studies employing continuous cell lines, it has been found that while cultures of such cells become remarkably resistant to the destructive effects of a cell-killing virus if they are preinfected with a sublethal virus, they are not susceptible to the protective effect of interferons.^6,7,2 Such studies suggest that interferon may not be the sole mediary of this type of viral resistance.Henderson