Resumo

The human T-cell lymphotropic virus 2 (HTLV-2) is a member of the Retroviridae family and share some biological and molecular properties with HTLV-1. HTLV-2 is mainly found among Indians from the Americas and intravenous drug users (IDU) from US, Europe, and Brazil. There are some limitations of employing the present commercial serological assays for both diagnostic and epidemiological purposes in different geographical areas of the country, such as the Amazon Region, where the HTLV-2c is a unique molecular subtype occurring among several native Indians. With the phage display method, previously unknown conformational and linear epitopes of high affinity monoclonal and polyclonal antibodies have been successfully identified. In this study, IgG from patients with HTLV-2 and negative controls were covalently coupled to protein G-magnetic beads. After coupling, beads were washed and incubated with a PhD-12 library of random hepta-peptides expressed at the amino terminal of pIII coat protein of the filamentous bacteriophage M13, which has a diversity of 109 peptides ( New England BioLabs, Inc) for biopanning. Our goal was to obtain specific peptide ligands to IgG that mimic HTLV-2 epitopes. After selection, 48 clones were tested in ELISA assays against sera from HTLV-2-infected patients and negative controls, and the highly reactive clones had their DNA sequenced and translated. Additional immunoassays were performed for those clones with valid sequences, which showed significant differences between patients and controls. We have further performed an in silico analysis and found relevant linear and structural alignments to viral antigens, such as the envelope glycoprotein and Gag-Pro-Pol polyprotein. The direct use of selected phage-fused mimotopes present a significant improvement in HTLV-2 diagnosis, and may become readily use for screening purposes in many different immunoassays.