The effect of HTLV-1 virulence factors (HBZ, Tax, proviral load), HLAclass I and plasma neopterin on manifestation of HTLV-1 associatedmyelopathy tropical spastic paraparesis

Hanieh Tarokhian, Mahdi Taghadosi, Hushang Rafatpanah, Taraneh Rajaee, Mahmoud Reza Azarpazhooh, Narges Valizadeh, S.A. Rahim Rezaee

Virus Research: 2017; 228:1-6.

Background: Previous studies have suggested debatable roles of Tax and HBZ gene expression in thepathogenesis of HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). In this study,HTLV-1 and host interactions in the manifestation of HAM/TSP were evaluated.

Methods: A cross-sectional study was conducted on 33 HAM/TSP patients and 38 HTLV-1 asymptomaticcarriers (ACs). HTLV-1-Tax, HBZ gene expression, and proviral load (PVL) were assessed using the quan-titative real-time PCR (TaqMan), host plasma neopterin level, and HLA-I, and the clinical manifestationwere evaluated.

Results: The HTLV-1 PVLs in HAM/TSP and ACs were 306 ± 360.741 copies/104PBMCs and 250.98 ± 629.94copies/104PBMCs, respectively; the PVL was higher in HAM/TSP than that in ACs (p = 0.004). HTLV-1Tax and HBZ expression in HAM/TSP was higher than that in ACs, wherein only the Tax expression wasstatistically significant (p = 0.039). In contrast to Japanese HTLV-1-infected subjects, HLA-A*02, HLA-A*24,HLA-Cw*08, and HLA-B*5401 did not exhibit preventive effects for HAM/TSP manifestation.The plasma neopterin level was significantly higher in HAM/TSPs than that in ACs; furthermore, therewas a strong significant correlation between plasma neopterin and PVL (R = 0.76, p = 0.001).Moreover, there were significant correlation between urinary disturbances and haematological indices,including the RBC count (R = −0.61, p = 0.01) and Hematocrit (Ht) index (R = −0.75, p = 0.002), and betweenmobility disturbances with Tax expression (R = −0.58, p = 0.02) and WBC counts (R = −0.54, p = 0.04), andfinally, a significant association was found between the sensory disturbances and PVL (p = 0.05).

Conclusion: Overall, HTLV-1 PVL and Tax may be the valid predictors of disease development, and theneopterin level may be a valid predictor of disease progression. In addition, Tax and neopterin are morehelpful than PVL for the monitoring of HTLV-1-infected patients.

 Keywords: HAM/TSP, Proviral load, HBZ, Tax, Neopterin, HLA