The IFN-alpha-inducing capacity of Sendai Virus in human leukocytes is indipendent 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 ind uce natural human interferon alpha from fresh human leukocytes (Le-IFN-alph a) of healthy donors, were characterized for hemagglutinating (HA) and hemo lytic (HemA) activities and for SDS-PAGE proteic pattern. The SV preparatio ns were produced by a single passage or by serial propagations through eggs in different conditions of multeplicity of infection (m.o.i.). The produce d SV subpopulations showed variable IFN-inducing capacity, the values of wh ich are distributed over a 6-fold range resembling a Gaussian distribution. No detectable difference was observed comparing the SV preparation obtaine d by serial propagations with those obtained by a single passage. The varia bility 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 ind uced amount of IFN per cell. In the same experimental conditions to produce Le-IFN-alpha, u.v.-treated SV preparations were unable to induce interfero n 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 associ ated with divergent compositions of the viral RNAs rather than with a diffe rent contents of viral proteins, among those detectable in SDS-PAGE and tho se responsible for HA activity and for HemA activity.