Background and purpose: Brucellosis is a systemic infection caused by gram-negative coccobacilli and facultative intracellular bacteria of the genus Brucella. Interleukin-17 is one of the important cytokines that plays a role in controlling host immune response in patients with brucellosis. The aim of this study was to investigate polymorphism of the genes encoding IL-17 in patients with brucellosis compared to healthy subjects.
Materials and methods: This case-control study included 86 patients with brucellosis who were selected based on clinical symptoms, serology, culture and PCR results. The control group composed of 86 healthy people. The polymorphism gene encoding Interleukin-17 was evaluated in both groups by PCR-RELP method.
Results: Current study showed that the frequencies of AA [OR=0.047 (95%CI: 0.01-0.12)] and GG [OR=337.20 (95%CI: 20.49-5541.39] were significant at position -1998 (G/A) in both cases and controls [P-values (AA) and (GG) = 0.001]. But, the frequency of AA genotypes in the control group was greater than the frequency of GG genotype in patients. The odds ratio for catching brucellosis in people who have genotype GG was 41 times higher than those who have genotype AA.
Conclusion: Findings showed that, AA and AG genotypes at -1998 (A/G) position are more important. So, the risk of brucellosis in people with GG genotype at position -1998 was higher than that in people with AA genotype. In other words, people with AA genotype are more protected against brucellosis at this position.