HTLV-1 Proviral Load Absolute RT-qPCR Development for Assessing on Clinical Outcomes in HAM/TSP Patients

Background

The significance of HTLV-1 proviral load as a prognostic biomarker in HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) has been a subject of controversy. This study aims to assess the impact of HTLV-1 proviral load (PVL) on the clinical outcome in patients with HAM/TSP.

Methods

An absolute quantitative HTLV-1 PVL RT-qPCR, TaqMan method was developed with 100% sensitivity and specificity. Then, from 2005-2018, the HTLV-1 PVL of 90 eligible newly diagnosed HAM/TSP patients were assessed for demographic, clinical symptoms and their associations with HTLV-1-PVL.

Results

The quality control of the designed RT-qPCR showed a sensitivity and specificity of 100%. Spasticity in lower limbs in 58.9% and urinary symptoms in 17.8% of HAM/TSPs were observed. Using this designed RT-qPCR, the HTLV-1-PVL strongly affected spasticity and sphincter disturbance (p=0.05). The multivariate logistic test showed that only the beginning of lower limb weakness along with tremor was associated with PVL (OR: 2.78. 95% CI (0.99-1.02) and p=0.05). Urinary incontinence was prevalent among these patients; however, no association was identified with the HTLV-1 proviral load (PVL).

Conclusions

The absolute RT-qPCR developed for measuring HTLV-1 proviral load (PVL) demonstrated reliable results. Despite a high prevalence of urinary incontinence in these patients, no association was observed with the PVL. Consequently, it appears that HTLV-1 proviral load is specifically associated with developing spasticity in HAM/TSP.

Triple Therapy with Prednisolone, Pegylated Interferon and Sodium Valproate Improves Clinical Outcome and Reduces Human T-Cell Leukemia Virus Type 1 (HTLV-1) Proviral Load, Tax and HBZ mRNA Expression in Patients with HTLV-1-Associated Myelopathy/Tropical Spastic Paraparesis

Considering that there is no effective treatment for human T-cell leukemia virus type 1 (HTLV-1)-associated myelopathy/tropical spastic paraparesis, this study aimed to assess the impact of triple combination therapy-interferon-α, valproic acid, and prednisolone-on clinical outcomes, main HTLV-1 viral factors, and host anti-HTLV-1 antibody response. HTLV-1 proviral load (PVL), and HBZ and Tax mRNA expression levels were measured in peripheral blood mononuclear cells of 13 patients with HTLV-1-associated myelopathy/tropical spastic paraparesis before and after treatment with 180 μg pegylated interferon once a week, 10-20 mg/kg/day sodium valproate, and 5 mg/day prednisolone for 25 weeks using a TaqMan real-time polymerase chain reaction assay. Furthermore, anti-HTLV-1 titer, Osame Motor Disability Score, Ashworth spasticity scale, and urinary symptoms (through standard questionnaire and clinical monitoring) were assessed in patients before and after the treatment. HTLV-1 PVL and HBZ expression significantly decreased after the treatment [PVL from 1443 ± 282 to 660 ± 137 copies/10(4) peripheral blood mononuclear cells (p = 0.01); and HBZ from 8.0 ± 1.5 to 3.0 ± 0.66 (p < 0.01)]. Tax mRNA expression decreased after the treatment from 2.26 ± 0.45 to 1.44 ± 0.64, but this reduction was not statistically significant (p = 0.10). Furthermore, anti-HTLV-1 titer reduced dramatically after the treatment, from 3123 ± 395 to 815 ± 239 (p < 0.01). Clinical signs and symptoms, according to Osame Motor Disability Score and Ashworth score, improved significantly (both p < 0.01). Urinary symptoms and sensory disturbances with lower back pain were reduced, though not to a statistically significant degree. Although signs and symptoms of spasticity were improved, frequent urination and urinary incontinence were not significantly affected by the triple therapy. The results provide new insight into the complicated conditions underlying HTLV-1-associated diseases.