 Solution

The cytoplasmic viral signal stays predominantly at high molecular size despite longer nuclease treatment. The viral DNA is protected from digestion, plausibly inside viral capsids or assembled particles. This differs from a nucleosomal ladder: a capsid can shield a whole genome instead of producing repeated small protected units. Release into the cytoplasm during productive infection makes particle-associated DNA a reasonable interpretation.

The virus-negative lane argues against nonspecific hybridization. Protection alone nevertheless does not prove that all detected particles are mature or infectious; an inaccessible compartment or another protective assembly could also shield DNA. Comparing intact material with material whose protective envelope or capsid has been disrupted would distinguish enclosure from intrinsic nuclease resistance of the DNA. Fractionation controls would address nuclear contamination. The result is about physical accessibility of viral DNA, not a quantitative infectivity assay.