  The infection pathway of virus in living cell is of interest from the
viewpoint of the physics of diffusion. Here, recent developments about a
diffusion theory for the infection pathway of an adeno-associated virus in
cytoplasm of a living HeLa cell are reported. Generalizing fractional kinetics
successfully modeling anomalous diffusion, a theory for describing the
infection pathway of the virus over the cytoplasm is presented. The statistical
property of the fluctuations of the anomalous-diffusion exponent is also
discussed based on a maximum-entropy-principle approach. In addition, an issue
regarding the continuum limit of the entropy introduced in the approach is
carefully examined. The theory is found to imply that the motion of the virus
may obey a scaling law.
