Parasite vaccine development: large-scale recovery of immunogenic Taenia ovis fusion protein GST-45W(B/X) from Escherichia coli inclusion bodies.

Genetically modified Escherichia coli expressing the Taenia ovis fusion protein GST-45W(B/X) as inclusion bodies were grown in volumes ranging up to 1000 l. Bacteria were inactivated by heat or chemical treatment without affecting immunogenicity. The fusion protein was recovered in a highly immunogenic form from washed inclusion bodies and from urea-solubilised inclusion bodies. The fusion protein was found to be stable in solution after storage at 4 degrees C for up to 2 years. Vaccines formulated with fusion protein from urea-soluble inclusion bodies gave consistently high protection (89-100%) against challenge infection. The methods described enabled the production of sufficient vaccine for large field trials. These trials generated the data required for product registration and manufacture of a vaccine to prevent T. ovis infection in sheep.