1.   Although Jenner had used cowpox virus, a third virus, vaccinia, became the standard vaccine against smallpox.

2.   And in genetic medicine experiments, harmless viruses are used to carry desirable genes into cells.

3.   Because the Sabin vaccine is most effective in children, Mathieson noted, the engineered polio virus may be used on youngsters rather than adults.

4.   A later analysis of the viruses in both labs showed that both teams had ended up using this virus to make their blood tests.

5.   A young volunteer died in a gene therapy experiment using viruses in Pennsylvania last year, and there have been several other adverse reactions to viruses.

6.   Disabled viruses have been used to make vaccines against many diseases.

7.   For example, research using the virus might yield drugs against the disease, or improved vaccines to prevent it.

8.   For openers, most gene therapy companies use various viruses as carrier mechanisms when injecting DNA into cells.

9.   Gene therapy commonly uses viruses as vectors to carry DNA into cells, and a vector called adenovirus was implicated in the Pennsylvania death.

10.   If a lentivirus is needed because of its ability to infect nondividing cells, then animal viruses could be used instead of HIV.