A genetically engineered polio virus has activated animal immune systems like a vaccine, suggesting strategy for a safer polio vaccine and an immunization for hepatitis A, researchers say. The virus made the immune systems raise defenses against two different types of natural polio virus, according to a report in the British journal Nature.
The standard oral polio vaccine uses three types of live but weakened polio viruses. That stimulates the immune system to create proteins, called antibodies, to attack each type. The vaccine is considered safe, but in rare cases can produce polio, which is blamed on its "type 2" and "type 3" virus strains, the researchers said.