11.   Jonas Salk grew polio virus in live animal cells, separated out the virus, then killed the virus with formaldehyde.

12.   Laboratories around the world are being asked to destroy or lock up remaining stocks of polio virus.

13.   The new test showed evidence that the polio virus also had affected the ones in her arms.

14.   The oral polio vaccine, also made from a live but weakened strain of the polio virus, has practically eliminated that paralyzing disease.

15.   The research showed unequivocally that a vaccine would have to include three distinct types of polio virus, but no more.

16.   The researchers were pleased to find that the samples did not contain live polio viruses.

17.   These viruses, like the polio virus, are packed inside a tough protein shell that protects them.

18.   These immunization drives rely on the Sabin vaccine, which is given orally and uses a live but weakened form of the polio virus to stimulate immunity.

19.   Unlike the Salk vaccine, the oral version contained a live but weakened form of polio virus and promised lifelong immunity.

20.   Vaccines eliminated the dreaded polio virus.