Finnbogi, the F-Prot's dev, has uploaded an updated (and the last for DOS) version 3.16f with the latest and LAST 2009 definitions. Download it from:

https://ozgur.kazancci.com/down/fprot_dos_316f.zip

But there is a problem! We're in 2020 and running F-PROT.exe gives the following message;

"The SIGN.DEF file is too old to be of use. It will probably only detect a fraction of the viruses that exist today. Please obtain and install an up-to-date version. Press any key to continue."

then it quits to the DOS prompt.

LUCKILY, using the /OLD switch disables the date check of the definitions!

So the command would be: 

F-PROT.exe /OLD


Here's the original post from the dev:

"
The last definition files we created that were compatible with F-Prot for DOS 3.16f are from beginning of February 2009.
Here's a download link to the LAST F-Prot for DOS
Best regards,
Finnbogi"