Association of the p75 NTR Ser205Leu Polymorphism with Asymptomatic HTLV-1 Infection.

Genetic variations in components of the immune response seem to be an important factor that contributes to the manifestation of symptoms of some diseases related to HTLV-1 infection. Nerve growth factor (NGF) and the p75 neurotrophin receptor (p75 NTR ) are related to the maintenance of neurons and the activation of the immune response. In this study, we evaluated the association of the NGF -198C/T, NGF Ala35Val , and p75 NTR Ser205Leu polymorphisms with HTLV-1 infection and plasma cytokine levels in 166 samples from individuals infected with HTLV-1 (59 symptomatic and 107 asymptomatic). The genotyping and quantification of the proviral load were performed by real-time PCR, and cytokine levels were measured by ELISA. The NGF -198C/T and NGF Ala35Val polymorphisms were not associated with HTLV-1 infection. The frequency of the Ser/Leu genotype of p75 NTR Ser205Leu was more frequent in the control group ( p = 0.0385), and the Ser/Leu genotype and allele Leu were more frequent among the asymptomatic ( p < 0.05), especially with respect to the HTLV-1-associated myelopathy (HAM) group ( p < 0.05). The symptomatic showed a higher proviral load and higher TNF-α and IL-10 levels ( p < 0.05). Asymptomatic carriers of the Ser/Leu genotype ( p = 0.0797) had lower levels of proviral load and higher levels of TNF-α ( p = 0.0507). Based on the results obtained, we conclude that the p75 NTR Ser205Leu polymorphism may be associated with reduced susceptibility to HTLV-1 infection, a lower risk of developing symptoms, including HAM, and better infection control.