11.   The early boot sector and file viruses attacked MS-DOS, the text-based operating system from Microsoft.

12.   The virus also attacks horses.

13.   The virus attacked and quickly destroyed the immune systems of the doomed monkeys.

14.   The survey, the Agriculture Department claimed, proved that wild populations of the squash are not attacked by viruses.

15.   The virus attacks cloven-hoofed animals, leaving them underweight, weak and unable to produce milk.

16.   This virus attacks the liver and can be fatal.

17.   Viruses attack a specific weakness in an operating system or software that uses that system.

18.   When a virus attacks a bacterium, it can do one of two things.

19.   Young needed a new heart because an unknown virus attacked his heart, causing it to become so weak it was unable to pump blood adequately.

20.   Abdalla said the virus can attack people who slaughter infected animals, or they can catch it by eating infected meat.