Brucella is a gram negative bacteria causing a zoonotic disease.It is  intracellular buge located specially in chronic stage in reticuloendocthelial systen,spleen,bones and joints.Till now they do believe it causes a disease in the form of hypersenstivity delayed type.the question is what is the mechanism of its pathogenecity?

intracellular protein Brucellergene use in delayed type hypersensitivity reaction for diagnosis of Brucellosis which induce this type of reaction. if we returned to pathogenesis of brucellosis majority of phagocytosed bacteria can be destroyed by phagocytic cell which that have been opsonized in contrast to non-opsonized. the reaction of phagocytes with t cells which known cell mediated immunity and known as defensive mechanism against brucella is responsible  for DTH reaction which appears as granulomatous reaction and can be tested by intradermal injection and thickening observation.

Here is a study according to which B. abortus

is harboured by immune cells.

https://www.ucdmc.ucdavis.edu/publish/news/newsroom/8114

https://www.researchgate.net/publication/255974354_PPAR-Mediated_Increase_in_Glucose_Availability_Sustains_Chronic_Brucella_abortus_Infection_in_Alternatively_Activated_Macrophages

Regards,

Joachim

Article PPARγ-Mediated Increase in Glucose Availability Sustains Chr...

Brucellea causes delayed type hypersensitivity can detect that by gamma interferone.

I worked about that by using brucellin in skin test