"GenB" is short for "generic boot sector infector" and "GenP" for "generic partition sector infector". There are no such viruses at all. These are simply a "shorthand" that McAfee SCAN uses to tell you that it is sure there is something suspicious in your diskette's boot sector (GenB) or your hard disk's MBR (GenP) but it doesn't know precisely what.
Disinfection & Removal
F-Secure anti-virus products detect the viruses known to McAfee as "GenB" or "GenP" by their CARO names.
The last time we looked, SCAN detected the following viruses as "GenB" or "GenP": Abs-3, AntiCMOS, B2, Boot-Y, BootEXE, Crazy_Eddie, Den_Zuko, Digress, Eko_Terror, Exe_Bug, Flip, Frankenstein, Gena, Hex, Ibex, JKTK, Joshi, KeyDrop, Malaga, MPHTI, MZ_Boot, Peanut, Pilgrim, Pretty, Revolution, Rm, SBP, Sciagura, Screaming_Fist, Silly, Smile, Stakkabo, Strange, Tequila, Tiso, Tony_Boot, Verify, VVM.B, X-Boot and Yeah.