TAX gene expression is associated with western blot patterns and high viral loadin HTLV-1 infected individuals

Western blot (WB) is a conventional confirmatory test for evaluating infection with HTLV-1; however, indeterminate WB patterns remain a significant concern. TAX is a key regulatory protein of the HTLV-1 virus that increases the expression of viral gene products. This study aimed to compare the TAX expression profile in individuals with WB-positive and WB-indeterminate and evaluate its association with HTLV-1 proviral load MATERIALS AND METHODS: This study was conducted on individuals with WB-positive and WB-indeterminate HTLV-1 who had been referred to the Iranian Blood Transfusion Organization (IBTO) between 2021 and 2023. A total of 60 WB-positive and WB-indeterminate individuals were included. To confirm the presence of the HTLV virus in samples, peripheral blood mononuclear cells (PBMCs) were separated using a Ficoll gradient, and nested PCR (nPCR) was performed on the extracted DNA. The expression of the TAX gene was determined using quantitative Real-Time PCR. Moreover, the proviral load was measured using a TaqMan™ based qRT-PCR assay.

According to nPCR, TAX and LTR regions were detected in all samples (100%) with WB-positive patterns. In WB-indeterminate samples, 50% (15 out of 30) and 60% (18 out of 30) contained the TAX and LTR regions, respectively. The TAX expression in WB-indeterminate samples was significantly lower than in donors with positive WB results (p = 0.01). Furthermore, the median proviral load of HTLV-1 in WB-positive samples (28.55 Copies/106 PBMCs (IQR:9.18-78.57) was significantly higher than WB-indeterminate samples 0.46 Copies/106 PBMCs (IQR:0.15- 0.73).

This study revealed that TAX expression may influence indeterminate WB patterns, highlighting the importance of employing molecular testing along with serological assays.