For Wine, if you have a virus in there, I'm doubtfull it will go far into the Linux side.
Still, I found the idea interesting. If the file system is available to Wine and not sandboxed, It could damage files...
In the Linux viruses departement, I have seen a few, they were mainly on servers. Most dealt with email services.
Note that these systems needed some "updates love" and could've been better armored with that.
But I digress, if you have important data, backup (or I should say BACKUUUUP!!!!) and keep copies elsewhere NOT on your computer/network.
I have most of my important stuff in my daily backpack, so if the house burns down, I have a (semi)up-to-date backup
.
I almost lost everything "data" once (years of school/work, personal photos,etc.) from an electrical problem.
I still bless the Silicon Deities to this day that I worked in a computer shop at the time because because of the six circuit boards I found that physicaly fitted my harddrive ONE was compatible with the physical drive and made my data available. If I lost my data to a CryptoVirus... I would have lost everything.
Bonus : Since then, I have my data on my computer/replicated every few days to my network drive which is in RAID 1 (two hard drives, if one fails you don't lose data) and a USB hard drive that follow me around. Uh yeeeah... I'm not a fan of cloud backups.