Immune responses associated with protection in sheep vaccinated with a recombinant antigen from Taenia ovis

This paper describes the evaluation of the protective antibody response of sheep to vaccination against Taenia ovis infection with a defined recombinant antigen (45W). Sera from 181 vaccinated sheep, collected prior to experimental challenge with T.ovis , were assessed for 45W specific IgA, IgG, IgG₁, IgG₂ and IgM levels and these results correlated with protection data. There were significant relationships (P < 0.001) between IgG, IgG₁ and IgG₂ titres and protection. Serum IgA levels did not correlate with protection and there were no significant levels of 45W specific IgM detected. Killing of several other taeniid cestodes has been shown to be complement mediated and the findings in this study are consistent with the involvement of this immune mechanism in 45W vaccinated sheep. A comparison of the adjuvants used in this study (saponin and oil in water) demonstrated that whereas both adjuvants stimulated the production of similar levels of 45W specific IgG₁, the IgG₂ response was significantly higher in sheep vaccinated with oil adjuvant.