Flu Shot Made From Caterpillars May Win U.S. Vote

Armyworn Cells

Protein Sciences extracts genes from the dead flu virus and inserts it in a virus that feeds on a tropical caterpillar known as an armyworm. The virus is then exposed to ovary cells harvested from a single caterpillar and reproduced in large quantities. Ovary cells are used because they remain stable as they are cultured in a laboratory.

The caterpillar virus feeds on the ovary cells in vessels similar to those used to ferment beer, and there isn’t the variability of trying to grow a live flu virus that isn’t well adapted for chicken eggs, he said. The consistency of the caterpillar virus growth cuts down on the manufacturing time.

The end result is a vaccine made of protein and salt water, Adams said. Because the vaccine is pure, preservatives such as thimerosal aren’t necessary.