  Many simple RNA viruses enclose their genetic material by a protein shell
called the capsid. While the capsid structures are well characterized for most
viruses, the structure of RNA inside the shells and the factors contributing to
it remain poorly understood. We study the impact of base pairing on the
conformations of RNA and find that it undergoes a swollen coil to globule
continuous transition as a function of the strength of the pairing interaction.
We also observe a first order transition and kink profile as a function of RNA
length. All these transitions could explain the different RNA profiles observed
inside viral shells.
