Conserved Motifs within Hepatitis C Virus Envelope (E2) RNA and Protein Independently Inhibit T Cell Activation

T cell receptor (tcr) signaling is required for t-cell activation,proliferation,differentiation,and effector function. hepatitis c virus (hcv) infection is associated with impaired t-cell function leading to persistent viremia,delayed and inconsistent antibody responses,and mild immune dysfunction. although multiple factors appear to contribute to t-cell dysfunction,a role for hcv particles in this process has not been identified. here,we show that incubation of primary human cd4+ and cd8+ t-cells with hcv rna-containing serum,hcv-rna containing extracellular vesicles (evs),cell culture derived hcv particles (hcvcc) and hcv envelope pseudotyped retrovirus particles (hcvpp) inhibited tcr-mediated signaling. since hcvpp’s contain only e1 and e2,we examined the effect of hcv e2 on tcr signaling pathways. hcv e2 expression recapitulated hcv particle-induced tcr inhibition. a highly conserved,51 nucleotide (nt) rna sequence was sufficient to inhibit tcr signaling. cells expressing the hcv e2 coding rna contained a short,virus-derived rna predicted to be a dicer substrate,which targeted a phosphatase involved in src-kinase signaling (ptpre). t-cells and hepatocytes containing hcv e2 rna had reduced ptpre protein levels. mutation of 6 nts abolished the predicted dicer interactions and restored ptpre expression and proximal tcr signaling. hcv rna did not inhibit distal tcr signaling induced by pma and ionomycin; however,hcv e2 protein inhibited distal tcr signaling. this inhibition required lymphocyte-specific tyrosine kinase (lck). lck phosphorylated hcv e2 at a conserved tyrosine (y613),and phospho-e2 inhibited nuclear translocation of nfat. mutation of y613 restored distal tcr signaling,even in the context of hcvpps. thus,hcv particles delivered viral rna and e2 protein to t-cells,and these inhibited proximal and distal tcr signaling respectively. these effects of hcv particles likely aid in establishing infection and contribute to viral persistence. © 2015 zaika et al.