  The problem of RNA genomes packaged inside spherical viruses is studied. The
viral capsid is modeled as a hollowed sphere. The attraction between RNA
molecules and the inner viral capsid is assumed to be non-specific and occurs
at the inner capsid surface only. For small capsid attraction, it is found that
monomer concentration of RNA molecules is maximum at the center of the capsid
to maximize their configurational entropy. For stronger capsid attraction, RNA
concentration peaks at some distance near the capsid. In the latter case, the
competition between the branching of RNA secondary struture and its adsorption
to the inner capsid results in the formation of a dense layer of RNA near
capsid surface. The layer thickness is a slowly varying (logarithmic) function
of the capsid inner radius. Consequently, for immediate strength of RNA-capsid
interaction, the amount of RNA packaged inside a virus is proportional to the
capsid {\em area} (or the number of proteins) instead of its volume. The
numerical profiles describe reasonably well the experimentally observed RNA
nucleotide concentration profiles of various viruses.
