1.   The vaccine protects against Hepatitis B, a highly infectious virus.

2.   Also known as smallpox, the highly infectious virus is seen as an even bigger threat than anthrax because it is contagious and can infect with a single particle.

3.   But the American Red Cross does test blood for Hepatitis B, in addition to a number of other potentially infectious viruses, such as HIV.

4.   By mapping the genes of both human beings and infectious viruses and bacteria, she said, scientists can devise new methods for fighting these tiny but deadly enemies.

5.   Carriers of the highly infectious virus can infect other people even without having symptoms themselves.

6.   Fighting fire with fire, scientists are enlisting the help of other infectious viruses to seek and destroy cells harboring the AIDS virus.

7.   For others, the illness may have been preceded by a cold or flu, but there is no evidence that the infectious virus still lingers in any form.

8.   One theory is that the use of multiple drugs can block the production of new infectious virus particles and that the cells harboring the virus die.

9.   That infectious virus is loose in America.

10.   Who wanted to fool around with live infectious viruses when you could pop a few penicillin pills and be as good as new?