No Evidence of HTLV-II Infection Among Immonoblot Indeterminate Samples Using Nested PCR in Mashhad, Northeast of Iran

Objective(s): Although HTLV-I infection is endemic in different geographical parts of the world including Northeast of Iran, there have been no documents of HTLV-II infection in this region. It is reported that one possible reason for seroindeterminate state in HTLV western blot is HTLV-II virus. This study aimed to investigate the presence of HTLV-II among blood donors with seroindeterminate western blot results. Materials and Methods: Three ml whole blood obtained from 50 blood donors referring to Mashhad Blood Transfusion Organization who had reactive Elisa for HTLV-I and seroindeterminate HTLV western blot state. A conventional PCR was applied to detect HTLV-I provirus using specific primers while a nested PCR was designed with specific external and internal primers for the detection of HTLV-II. Results: The average age of participants, 39 males and 11 females, was 37.12± 14.36 years. The average OD of the Elisa assay was 1.767± 1.195. The most common indeterminate patterns were Rgp46-II alone (n=12, 27.3%), Rgp46-I alone (n=7, 15.9%), and Rgp46-I with GD21 (n=7, 15.9%).After introducing the DNA to the PCR tests, results revealed 10 (20%) HTLV-I PCR positive samples while no HTLV-II positive sample was detected by nested PCR. There were no significant age, blood group, Optical Density of the Elisa assay, and western blot indeterminate pattern differences between HTLV-I PCR positive and negative samples. Conclusion: No HTLV-II positive sample was detected in this study which confirms the absence of HTLV-II infection in this region. However, high frequency of HTLV-I PCR positive samples among the seroindeterminate cases implies on the important role of molecular techniques for further confirmation of the infection.