Viral ssRNAs are indeed compact.

DNA is the genetic material of all living things, except for viruses, most of which have genomes that are RNA – not DNA. Further, the majority of viral RNA genomes are single stranded (ss) rather than duplex chains. The simplest of these ssRNA viruses, whether infecting bacteria, plants, or animals, involve a single copy of their genome, protected (“packaged”) by a single-molecule-thick spherical shell (“capsid”) of protein, which is typically smaller than 25 nanometers (nm) in radius. The small size is advantageous for minimizing the amount of viral protein needed for each viral particle (virion) and for maximizing the number of these infectious units that can be made by each host cell. Finally, and perhaps most remarkably, many ssRNA viruses can be spontaneously self-assembled by simply mixing their genome and capsid protein. These facts suggest that a ssRNA viral genome should be as compact a 3D object as possible.