[Genome of defective interfering influenza virus particles: multiple reactivation of "incomplete" virus detectable by counting hemadsorbing cells].

: Gel electrophoresis reveals additional segments of low molecular mass in RNA preparations of "incomplete" (produced by passages of undiluted material according to von Magnus) influenza virus which are lacking in RNA of the standard virus. When MDCK cells are inoculated with the "incomplete" virus, synthesis of virus-specific proteins is observed but the pattern of relationships between the intensity of the synthesis and multiplicity of infection is different from that of the standard virus. Quantitative determination of infectivity by counting of haemadsorbing cells demonston the dilution of the "incomplete" virus in contrast to the linear dependence in infection with the standard virus. Neither the virus-specific protein synthesis nor cell conversion into the haemadsorbing state can be due to the admixture of infectious particles in "incomplete" virus preparations and indicate an effect of the type of multiple activation of virus genome expression.