Background: Nephropathia epidemica (NE) is a mild type of haemorrhagic fever with renal syndrome caused by Puumala (PUU) hantavirus. The clinical course of NE varies from asymptomatic to fatal. The aim of this study was to establish whether polymorphisms in the cytokine genes are associated with susceptibility to and outcome of NE.
Methods: The genotypes of the genes of tumour necrosis factor alpha (TNFalpha), interleukin-1alpha (IL-1alpha), IL-1beta and IL-1 receptor antagonist (IL-1RA) were analysed by polymerase chain reaction in 87 subjects, all hospital-treated for serologically confirmed acute NE. The control group comprised 400 healthy blood donors. Nineteen out of these 400 (5%) controls were PUU virus-seropositive.
Results: IL-1RA allele 2 and IL-1beta (base exchange polymorphism at position -511) allele 2 were strongly associated with each other in both groups. NE patients were more often IL-1RA-2 negative/IL-1beta-2 negative than PUU-seronegative blood donors (38 vs 27%, odds ratio 1.65, 95% confidence interval 1.0-2.7). However, there were no differences in the clinical severity of NE between the IL-1RA-2 negative/IL-1beta-2 negative and the other patients. The other allele frequencies studied evinced no statistically significant differences between the groups. Thirty-three out of 87 (38%) patients and 121 out of 381 (32%) seronegative controls were carriers of the high-producer genotype TNF2 allele. Several parameters showed the clinical course of NE to be more severe in TNF2 carriers than in non-carriers.
Conclusions: These data suggest that non-carriage of the IL-1RA allele 2 and IL-1beta (-511) allele 2 may contribute to susceptibility to NE. Furthermore, TNFalpha polymorphism seems to be associated with the outcome of NE.