the rna of virus strains capable of transforming chick embryo fibroblasts in vitro always contained a subunits : the rna of pr-rsv of subgroups a , b or c was composed only of a subunits , even after prolonged passage in chick cells , whereas the rna of sr-rsv-a , sr-rsv-b , sr-rsv-d ( h ) and b77 also contained b subunits in varying amounts , even when examined as early as possible ( 8-10 days ) after cloning .
C0016030
fibroblasts
C0007634
cells