1.   First, how many types of polio virus existed?

2.   So, a polio vaccine tricks our body into making antibodies to the polio virus.

3.   The polio virus first invades the intestines, where it lives, replicates, and usually establishes harmless infection.

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

5.   Because the polio virus enters the bodies of those it infects through the intestinal tract, the vaccine can be taken orally.

6.   Every year, about eight children contract paralytic polio from the oral vaccine, which is made from a live, weakened polio virus.

7.   His team showed that the polio virus was transmitted among people chiefly by fecal contamination, usually through soiled hands.

8.   In their experiments, the researchers inserted two specific genes from the core of the AIDS virus into the weakened polio virus.

9.   It is not a recurrence of the polio virus itself, but a further weakening of muscles and deterioration of nerves that were previously injured by the polio virus.

10.   Intestinal immunity is of great value because the polio virus enters the body through the digestive tract and is shed in stools, which can infect others.