Immune response strategies of Brucella melitensis and their antigens in rats

Brucella melitensis is an intracellular bacterium and is the main brucella species that cause abortion and placenta retention in sheep and goats. It has many mechanisms to evade the immune response. The current study aimed to investigate Brucella melitensis strategies for producing immune responses in rats after challenging the bacterium. For this purpose, live and killed Brucella melitensis REV1 strain was given to rats subcutaneously, and immunological markers like TLR2, TLR4, IFN- γ, and anti-brucella antibodies were determined. The results showed that the level of immunological markers like TLR2 and TLR4 did not significantly increase in rat groups inoculated with live Brucella melitensis, while it increased in the rats’ groups vaccinated with the sonicated Brucella melitensis; also, the results showed an increase in the level of IFN-γ and anti-brucella antibody titers in all animal groups. The study concluded that the inoculation with killed bacteria and REV1 could protect the animals against challenging doses, as seen when the groups were inoculated with challenge dose of the bacterium.