Virii is not a real word.
This is simply life cycle architecture that has, like the Admiral says, come about through natural selection. It might seem exotic or intentional, but it's no different to viruses recognising which cells to infect.
You need to be careful about this sort of analysis, because whereas you have interpreted that rabies travels to the brain to do its work, it's more likely that it travels through the blood or lymph systems aimlessley, and only acts in the brain, where its target cells are.