Is there any risk of installing Windows operating systems on my MacBook Pro using VirtualBox?

Q: I would like to know if there is any risk of installing windows operating systems on my MacBook Pro using VirtualBox. My understanding is, yes the virtual windows machine could get a virus but would it also transfer that virus to my mac operating system. For instance some viruses that make copies of everything as .exe would I have that happen on my mac files as well or just on the virtual machine? My idea was if I had windows installed on virtualbox and backed it up I could then delete it if I got a virus and then just start up a new machine. I hope this all makes some sense.