Process of Infection with ϕX174: Effect of Exonucleases on the Replicative Form

When a preparation containing the DNA of the bacteriophage øX174 in its replicative form together with DNA from Escherichia coli is treated with exonucleases, the replicative form retains its characteristic physical properties, while the bacterial DNA is degraded. The evidence suggests that the mature replicative form exists as a closed ring.