Evaluation of the humoral immune response in adult dairy cattle three years after vaccination with a bluetongue serotype 8 inactivated vaccine.

Despite the widespread use of bluetongue serotype 8 (BTV-8) inactivated vaccines across Europe from 2008 to 2011, two very practical questions remain unanswered about the length of persistence of group-specific antibodies in milk and serum post-vaccination and the duration of protection beyond one year post-vaccination. This study has firstly revealed that group-specific antibodies persist at high levels in milk and serum in the majority of cattle for at least 3 years post-vaccination, thus removing the option of using these animals in ELISA-based surveillance programmes. Secondly neutralising antibodies have been shown to persist in the majority of cattle for at least 3 years post-vaccination, indicating that the cattle are likely to be protected for this time period. This extended duration of protection may have contributed towards the rapid and efficient eradication of BTV-8 from many European countries, despite reducing levels of vaccine coverage.