Anti-Virus Tools
From CIAC, a listing of mainly DOS anti-virus tools, though it does include some Windows utilities.

AVP Lite
While no longer free but still inexpensive, AVP Lite from Kaspersky is one of the easiest and most effective antivirus products for DOS.

Command AntiVirus for DOS
Portable and configurable, Command AntiVirus for DOS even defends against macro virus infections. Run via command-line or with the graphical interface. Includes logging capabilities.

DOS File Viruses
From Kaspersky, a list of file viruses and their accompanying descriptions infected DOS-related files.

F-Prot
Frisk offers solid antivirus protection free for single, home use and incredibly cheap for enterprises.

Protector Plus
Proland's DOS version checks the boot sector and the partition table when the computer is re-booted. If an infection is detected, the boot sector and the partition table are rebuilt.

Sophos Anti-Virus
Sophos provides antivirus protection for DOS 5.0 users. Supports both FAT and FAT32 file systems.

VSUM
For obvious reasons, this resource on DOS viruses hasn't been updated since Sept. 98. Still, a good source for DOS virus information.