Assessing the presence of tax and LTR genes in subjects infected with the Human T-cell lymphotropic virus type ۱ (HTLV-۱)

Background and Aim: Human T-cell lymphotropic virus type ۱ (HTLV-۱) is a retrovirus which is associated with adult T-cell leukemia/lymphoma (ATLL) and a neurologic disease called tropical spastic paraparesis/ HTLV-۱-associated myelopathy (HAM/TSP). While infection with this virus is reported globally, certain parts of the world such as Japan, Africa, Caribbean islands, South America and northeastern of Iran are endemic for it. Screening for HTLV-۱ infection in endemic regions is cost effective and prevents both mortality and serious morbidity. Diagnosis of HTLV-۱ infection is feasible, yet involves different steps. Suspected individuals are initially screened for HTLV-۱ specific antibodies by Enzyme linked immune sorbent assay (ELISA). Positive cases need to be confirmed with an alternative test. Polymerase chain reaction (PCR) is currently the most widely used technique to confirm serological assays. Amplification of the tax, pol or LTR regions are usually applied. It is not clearly documented what percentage of samples are positive for each region. We conducted this study to measure the percentage of positive results in PCR assay for the tax and LTR regions.Methods: The serum samples of ۱۶۷ samples which were positive in screening for HTLV-۱ specific antibodies by ELISA were assessed for the HTLV-۱ genome by PCR method using the tax and LTR specific primers to confirm the infection.Results: From the total ۱۶۷ samples, ۱۳۱ (۷۸.۴۴%) were positive for both tax and LTR, ۲۰ (۱۱.۹۸%) samples were positive for LTR but negative for tax, ۱۰ (۵.۹۹%) were positive for tax and negative for LTR and the remaining ۶ (۳.۵۹%) were negative for both regions.Conclusion: Given the fact that samples are considered positive for HTLV-۱ infection if either gene is amplified in PCR, ۹۶.۴۱% of positive cases in ELISA were confirmed with PCR. Cases which were negative for both need to be assessed with Western Blot.