Abstract
Clonally derived stocks of defective-interfering (DI) influenza virus prepared in chick embryo fibroblast (CEF) cells were all deficient in genomic RNAs 1, 2 and 3 but had different patterns of subgenomic RNAs. A single passage at high multiplicity in L cells altered the pattern of genomic RNAs independently of the subgenomic species, while in BHK cells the opposite situation prevailed. Therefore, there is no simple relationship in DI influenza virus between the loss of genomic RNA segments and the presence of subgenomic RNAs.