The role of DNA/RNA core on free vibration characteristics of viral capsids

A three-dimensional free-vibration model of core–shell structural spherical viruses submerged in non-Newtonian fluids is investigated to study the effect of the DNA/RNA core (Young's modulus and volume) on vibration characteristics (frequencies, damping time, and quality factor) of viral capsids. With this model and physically realistic parameters, the existence of DNA/RNA core is studied and compared with the empty shell model and the solid sphere model. Our results show that actual natural frequencies of spheroidal and torsional modes of a capsid can be much higher than those predicted by the empty shell model and lower than those predicted by the solid sphere model, which is contrary to the damping time and quality factor. In addition, the role of the stiffness transition and volume change of cores occurring in the maturation process on the vibration characteristics of capsids is further investigated. Our results estimate a longer damping time for mature viruses with a relatively smaller Young's modulus and larger volume of core, leading to the conclusion that mature viruses maybe more easier than immature viruses to be destroyed by acoustic resonance. With physically realistic parameters for some typical spherical viruses submerged in body fluid such as the blood, the present model predicts that the natural frequencies are in the GHz region and the damping time are in the ps region, which is qualitatively consistent with some simulation and experimental results. The present model provides a theoretical foundation and guidance for destroying sphere viruses in human body fluid by exciting the mechanical vibrations of viruses.