viral complementary dna ( cdna ) sequences corresponding to the gag , pol , env , src , and c regions of the rous sarcoma virus genome were selected by hybridizing viral cdna to rna from viruses that lack the env or src gene or to polyadenylic acid [ poly ( a ) ] -containing rna fragments of different lengths and isolating either hybridized or unhybridized dna .
C0012939
viral
C0012854
dna