There will be several ways to accomplish this. After some tinkering I was able get it by making my Virus slightly larger than my tiles allowing me to check tiles that my current Virus is overlapping to potentially move to the next square. I added in a tracker for Virus life which drops down as time goes and eventually turns back into a healthy square.
Check out my Video for details:
youtu.be/BIoVQBCXtI4