Protective response to Brucella infection

Brucella ovis causes an important disease characterized by decreased fertility in rams, sporadic abortions in ewes and increased lamb mortality. The live attenuated B. melitensis Rev.1 vaccine is considered the best vaccine available against this infection. However, this vaccine shows variable protective efficacy ranging from 40% to 100%.The objective of this study was to identify possible correlates of protective response to B. ovis infection through the characterization by microarray hybridization and real-time RT-PCR of inflammatory and immune response genes upregulated in rams previously immunized with the B. melitensis Rev 1 vaccine strain and experimentally challenged with B. ovis. Gene expression profiles were compared before and after challenge with B. ovis between rams protected and those vaccinated but found infected after challenge. The genes upregulated in vaccinated and protected rams provide possible correlates of protective response to B. ovis infection in rams immunized with the B. melitensis Rev 1 vaccine. Gene expression profiles were compared before and after vaccination and challenge with B. ovis between rams protected with the B. melitensis Rev 1 vaccine strain and those vaccinated but infected after challenge. Total RNA was isolated from buffy coat samples before vaccination (T0), after vaccination and before challenge (T1) and 60 days post challenge (T2) using TriReagent (Sigma, St. Louis, MO, USA)