IMMUNOLOGICAL INVESTIGATIONS OF HHV-6 U12 AND U51 ENCODED PROTEINS INVOLVEMENT IN AUTOIMMUNE THYROIDITIS DEVELOPMENT

Human herpesvirus 6 (HHV-6) is a human pathogen with a wide cell tropism and many immunomodulating properties. HHV-6 has been linked to the development of multiple diseases, among them – autoimmune. Conflicting evidence implicates HHV-6 in autoimmune thyroiditis (AIT). HHV-6 contains two genes (U12 and U51) that encode putative homologues of human G-protein-coupled receptors (GPCR) like CCR1, CCR3 and CCR5. It has been shown that proteins encoded by HHV-6 U12 and U51 genes can be expressed on the surface of epithelial and some peripheral blood mononuclear cells populations, which makes them a potential cause for evoking autoimmunity. The aim of this study was to identify potentially immunogenic synthetic peptides derived from HHV-6 U12 and U51 amino acid sequences and to find evidences of the possible involvement of these proteins in AIT development. 62 AIT patients positive for HHV-6 infection were enrolled in this study. 30 different synthetic peptides designed from HHV-6 U12 and U51 proteins’ amino acid sequences, as well as, recombinant human CCR1, CCR3 and CCR5 proteins were used for suspension multiplex immunological assay (SMIA) to detect specific IgG, and IgM antibodies. HHV-6 peptide specific IgG and IgM antibodies were found in patient’s samples, with higher signals for IgM antibodies, which is indicative of reactivation and active HHV-6 infection. As well recombinant CCR1 and CCR5 showed high signals on IgM antibodies which is indicating on the presence of potential auto-antibodies against human G protein-coupled receptors. No cross reactivity between HHV-6 peptide specific antibodies and human recombinant CCR1, CCR3 and CCR5 was found, however, the possibility of cross-reactive autoantibodies specific for structural epitopes cannot be excluded.