Sanaz Ahmadi Ghezeldasht - Blood Borne Infections Research Center, Academic Center for Education, Culture and Research (ACECR), Mashhad, Iran
Atefeh Yari - Department of Virology, Faculty of Public Health, Tehran University of Medical Sciences, Tehran, Iran
Arman Mosavat - Blood Borne Infections Research Center, Academic Center for Education, Culture and Research (ACECR), Mashhad, Iran
Seyyed Abdolrahim Rezaee - Immunology Research Center, Department of Inflammation and Inflammatory Diseases, Mashhad University of Medical Sciences, Mashhad, Iran

HTLV-1 is the first human retrovirus recognized and associated with the HAM / TSP and ATLL. Studies have shown that that approximatelyninety-five percent of carriers infected with HTLV-1 remain asymptomatic and less than five percent develop an inflammatory neurologic disease, mainly HTLV-1 Associated Myelopathy/Tropical Spastic Paraparesis (HAM / TSP). Therefore, proviral loading with Tax mayaffect cellular genes such as cytokines and oncogenes, while being implicated in pathogenicity. Materials and Methods: To measure HTLV-1 activity, thirty HAM/ TSP patients, thirty HTLV-1 healthy carriers, and MT-2 cell line were evaluated. PBMCs were isolated andactivated using PMA and ionomycine. Real-time PCR and TaqMan methods were carried out using specific primers and fluorescence probes for Tax expression and proviral load assessment. B2microglobulin (β2m) and albumin were used as controls in Tax expression andin proviral load, respectively. Results: An insignificant increase in Tax expression was observed in HAM/TSP patients compared to healthy carriers. However, after lymphocyte activation there was a significant increase in Tax expression in HAM/TSP patients (P=0.042). TheProviral load in patients was significantly higher than in carriers. Moreover, there was a significant correlation between Tax mRNA expression in activated PBMCs and proviral load (R=0.37, P=0.012). Conclusion: Even if proviral load was considered as a valuable index for monitoring HTLV-1 infected individuals, the results of this study demonstrated that Tax expression in activated PBMCs along with proviral load assessment in HAM/ TSP patients are a more reliable factor for determining the prognosis and monitoring healthy carriers and HAM/TSP patients.