I will mainly review two works, one on spherical protein "cages'' and topological defects, one on quantum effects on filamentous molecules that can model, for example, DNA-DNA interactions. The protein "cage" (capsid) and the genetic material (DNA or RNA) are the two essential components of a virus. This will be taken as an excuse to point to mayor challenges for theoretical physics in the arena of biological problems, a story that is as old as Schroedinger's lectures on physics and life (1943) but still unsolved.