31.   Wilson uses the virus on one of the computers in front of the class.

32.   But rather than using a virus to shuttle the gene into the animals, the new work involved injections of DNA in solution.

33.   Salk became a hero to millions of Americans when he ignored scientific doubters and used killed virus to develop the first polio vaccine.

34.   Researchers had previously used viruses to deliver genes, but some scientists say bubbles may prove to work better.

35.   Researchers used a virus to shuttle the gene into cells.

36.   The gene therapy technique used a virus that had been linked to a gene that prompts production in the brain of dopamine, a chemical neurotransmitter.

37.   The HIV-mimic virus is used because monkeys cannot be lethally infected by HIV itself.

38.   The researchers said the non-viral technique has potential advantages over gene therapy that uses viruses.

39.   The therapies usually use a virus to carry genes into the tumor, an approach that has two problems.

40.   U.S. scientists are developing a pill for smallpox in case the deadly virus is used in a bioterrorist attack, and report promising results in tests on mice.