The Possible Protective Role of the Il6-174GC Genotype in Dengue Fever

Abstract

Dengue is the most important viral disease transmitted by arthropod vectors. At present, it is known four types of virus serotypes, DEN 1, 2, 3 and 4. Differences in the host susceptibility to infection as well as the severity of disease can not be due only to viral virulence. Variations in immune response as a consequence of polymorphisms in regulatory regions of cytokine genes may have influence on the disease outcome. The aim of this study was to verify the occurrence of associations between cytokine gene polymorphisms and Dengue Fever. Two hundred patients from Parana State and 313 control individuals from Southern and Southeastern Brazil were genotyped for single nucleotide polymorphisms (SNPs) of TNF -308 , IFNG +874 , IL6 -174 , IL10 -1082,-819,-592 and TGFB1 +869,+915 by PCR-SSP (kits One Lambda, CA, USA). Phenotype, genotype and allele frequencies were compared by chi-square test, with Yates' correction or Fisher's exact test. There was a negative association between IL6 -174 GC genotype and Dengue Fever (27.9% vs. 38.3%; P=0.015; OR=0.62; CI=0.42 - 0.91). Significant statistical differences with cytokine production phenotypes or alleles were not observed. These results suggest a protective role of IL6 -174 GC genotype for Dengue Fever.