Evaluation of relation between mutant VirB۲ virulence factor in Brucella melitensis with immunogenicity and intracellular survival

Objective: The Brucella melitensis virB operon, encoding a type IV secretion system (T۴SS), is required for intracellular replication and persistent infection in the mouse model. The product of the second gene of the virB operon, virB۲, is predicted to be localized at the bacterial surface, where they could potentially interact with host cells. Studies to date have focused on characterization of transposon mutations in this gene, which is expected to exert polar effects on downstream genes. We researched on the evaluation of relation between virB۲ mutant with immunogenicity in mouse model and intracellular replication in macrophages J۷۷۴. Materials and Methods: In order to determine whether VirB۲ is required for the function of the T۴SS apparatus, we constructed and characterized deletion mutation of virB۲ and kanamycin resistance gene replaced instead of virB۲. For demonstration of intracellular replication, macrophages J۷۷۴ and BALB/c mices were infected with wild type Brucella melitensis and mutated. Results: After ۴۸ h, number of mutated Brucella severe decreased severly compaired to wild type in macrophages J۷۷۴, and Brucella with virB۲ deletion decreased from ۱×۱۰۶ CFU/spleen less than ۱۰۰۰ CFU/spleen during ۸ weeks, also total IgG increased in both but IL-۱۲ and IFN-γ increased only in wild type. Conclusion: VirB۲ was essential for intracellular replication in mouse models and J۷۷۴ macrophages. The virB۲ mutant was unable to cause persistent infection in the mouse model, demonstrating the essential role of VirB۲ in the function of the T۴SS apparatus

کلیدواژه ها:

T۴SS ، Brucella melitensis ، virB۲ mutation ، Intracellular replication ، Immunogenicity ، بروسلا ملی تنسیس ، جهش virB۲ ، تکثیر درون سلولی ، ایمنی زایی