This is a not dangerous memory resident parasitic polymorphic virus. It hooks INT 21h, 27h and writes itself to the end of EXE files and to the beginnings of COM files, some "Pcflu" infects only EXE files. While executing it checks the system and sometimes displays the message:
Incorrect DOS version
Then it returns to DOS.
The virus contains the text string:
PC-FLU Mk II by Wizard 1991
Some of the viruses from this family hooks INT 8 (timer) and 9 (keyboard) sometimes. Then they periodically 'skip' the keys that are entered.
