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Association of interleukin - 18 gene polymorphism with susceptibility or protective effect to HTLV-1 infection

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Polymorphisms in promoter region of IL-18 genes have been studied in many chronic inflammatory and infectious disorders. For instance, the IL-18 -137 GG and -607CC polymorphisms have been associated with elevated expression of IL-18, which could contribute for the inflammatory process and favor the antiviral effects of this cytokine. In this study, we evaluated the IL-18 promoter region -137C/G and -607A/C polymorphisms in HTLV-infected patients exhibiting (HAM) or not (HAC) symptomatic disease and in healthy controls.


The promoter region polymorphic sites (-137C/G and -607A/C) were evaluated by polymerase chain reaction - sequence specific primers (PCR-SSP) analysis using peripheral blood DNA obtained from HAC (54), HAM (44) and healthy control (150) individuals. Proviral load of infected patients (HAC and HAM) was determined by real-time PCR.


The -607CC genotype was less frequent for HAC group (p=0.0501; OR=0.4890; CI=0.2480 to 0.9643), and infected patients (p=0.0232; OR=0.5207; CI=0.3033 to 0.8937) compared to healthy controls. The -607AC genotype was more frequent for HAC group (p=0.0387; OR=1.991; CI=1.043 to 3.801), and infected patients (p=0.0376; OR=1.757; CI=1.047 to 2.948) compared to healthy controls. No significant difference was observed for allelic and genotypic frequencies of the -137C/G among deferments groups. No significant difference was observed for allelic and genotypic frequencies of the -137C/G and -607A/C polymorphisms when correlated with proviral load.


The -607CC (high producer of IL-18) genotype exhibited protective effect against the infection, whereas the -607AC genotype conferred susceptibility to HTLV-1 infection.


Financial Support: FAPESP, CNPq, CTC/FUNDHERP and INCTC.

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Correspondence to Virgínia M D Wagatsuma.

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This article is published under license to BioMed Central Ltd. This is an open access article distributed under the terms of the Creative Commons Attribution License (, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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  • Promoter Region
  • Gene Polymorphism
  • Genotypic Frequency
  • Infected Patient
  • Polymorphic Site