Polymorphism in the First Intron of Interferon-Gamma Gene (+874T→A) in Iranian Patients with Brucellosis

Background: Brucella is a gram-negative bacterium, causing acute and chronic infection in humans and animals. Cell-mediated immunity is the main protective immune response against Brucella spp. Activation of macrophages by IFN-γ and generation of reactive oxygen intermediates and nitric oxide are the main immunologic mechanisms responsible for control of Brucella infection. Objective: To investigate the correlation between IFN-γ gene polymorphism and brucellosis. Methods: 195 patients with brucellosis, 186 healthy patients' family members and 82 healthy farmers who kept infected animals and consumed their contaminated dairy products were selected to take part in the study. IFN-γ genotyping at position +874 (T→A) was carried out by allele specific polymerase chain reaction (AS-PCR) method. Results: The frequency of AT and TT genotypes significantly increased in farmers compared to patients with brucellosis (P=0.03) while there was no significant difference in genotype distribution between patients and their healthy family members. Conclusion: IFN-γ (+874) AA genotype is probably a genetic factor that contributes to the susceptibility of the individuals to brucellosis.