The IFN-alpha-inducing capacity of Sendai Virus in human leukocytes is independent from the hemagglutinating and hemolytic activities and from the viral proteins of the Sendai Virus preparations

About 30 Sendai Virus (SV) preparations, examined for their capacity to induce natural human interferon alpha from fresh human leukocytes (Le-IFN-alpha) of healthy donors, were characterized for hemagglutinating (HA) and hemolytic (HemA) activities and for SDS-PAGE proteic pattern. The SV preparations were produced by a single passage or by serial propagations through eggs in different conditions of multiplicity of infection (m.o.i.).The produced SV subpopulations showed variable IFN-inducing capacity, the values of which are distributed over a 6-fold range resembling a Gaussian distribution. No detectable difference was observed comparing the SV preparation obtained by serial propagations with those obtained by a single passage. The variability of the measured HA activity and HemA activity and as well as the SDS-PAGE proteic pattern of the SV preparations did not correlate with the induced amount of IFN per cell. In the same experimental conditions to produce Le-IFN-alpha, u.v.-treated SV preparations were unable to induce interferon depending on the u.v.-treatment. So it can be concluded that the distinct nHu-IFN-alpha-inducing capacity of SV subpopulation could be mainly associated with divergent compositions of the viral RNAs rather than with a different contents of viral proteins, among those detectable in SDS-PAGE and those responsible for HA activity and for HemA activity.