1.   The virus attacks the plant, the flower does not open, and consequently no seeds are produced.

2.   The Melissa virus exploited a known weakness, but if a virus attacked computers attached to the Internet utilizing an unknown weakness, the results could be overwhelming.

3.   Some viruses attack bacteria, others attack body cells.

4.   A virus had attacked his heart.

5.   Doctors believe a virus may have attacked his heart at some point in his life.

6.   Earlier in an HIV infection, before there are symptoms of disease, the virus attacks another group of immune system cells called macrophages.

7.   For example, influenza viruses attack only the lungs because only the lung cells have a particular enzyme that the influenza virus needs to replicate.

8.   Ordinarily their mucus-coated surfaces filter out dust and bacteria, but when a cold virus attacks, the mucus coating swells up and clogs the nose.

9.   Since Microsoft Word is available on Macs and PCs, the same Word macro virus will attack either machine.

10.   The AIDS virus directly attacks the human immune system.