Urea/DTT solubilization of a recombinant Taenia ovis antigen, 45W, expressed as a GST fusion protein results in enhanced protective immune response to the 45W moiety.

Vaccination and challenge infection experiments were conducted in sheep using different forms of a recombinant protein (45W) from the cestode parasite Taenia ovis. 45W was expressed in Escherichia coli as a fusion protein with glutathione-S-transferase (45W-GST) and was produced as both soluble protein and insoluble inclusion bodies. Vaccination of animals with either the soluble or inclusion body derived protein resulted in the immune response being predominantly directed to the GST moiety of 45W-GST. Conversely, vaccination with 45W-GST which had been solubilized/treated with urea and dithiothreitol (DTT), elicited enhanced responses to the 45W moiety and significantly reduced responses to GST. Vaccination with all forms of 45W-GST protected sheep against experimental T. ovis infection. However, protection was highly correlated with anti-45W antibody levels and these were significantly higher in animals vaccinated with the urea/DTT treated form of 45W-GST. It is suggested that recombinant proteins expressed either with or without fusion partners may stimulate enhanced immune responses when incorporated in vaccine formulations in a denatured/reduced state.