9). The lipid raft disrupting agent, Ivacaftor chemical structure methyl-β-cyclodextrin (MCD), reversed E2-mediated inhibition of IL-2 secretion (Fig. 6A). After treatment with the PKCβ-selective inhibitor Go6976, MCD could no longer reverse the inhibitory effect of E2 on IL-2 secretion (Fig. 6B). In

summary, these data suggest that HCV E2 diversion of PKCβ to lipid rafts offers a novel mechanism for HCV to perturb cytokine secretion and to indirectly modulate host immune responses. In resolving HCV infection, a potent CD4+ (Th1-oriented) response precedes the maturation of a protective memory CD8+ T cell response.25 In contrast, the proliferative capacity of both HCV-specific CD4+ and CD8+ effector T cells is weak or absent during persistent infection.26 Molecular mechanisms that may contribute to this reduced T cell response include the presence of IL-10, increased expression of the inhibitory molecule, programmed death-1, and loss of costimulatory molecules such as CD86.27-29 Studies in humans

and mice have reported that the reduced proliferative capacity of CD4+ T cells during viral infection is accompanied by decreased levels of IL-2 secretion.30-32 Semmo et al.33 reported on the reduced proliferation of HCV-specific CD4+ T cells isolated from patients with chronic disease in concert with reduced IL-2 secretion. These investigators had previously demonstrated loss of IL-2 secreting CD4+ T helper cells in selleck screening library chronic HCV infection.18 In this study, we demonstrate that both serum from HCV-infected patients and HCVcc reduced T cell IL-2 release and that this inhibitory effect was mediated via E2-CD81 ligation. HCV-presented E1/E2 glycoproteins are multivalent and likely to cross-link CD81. However, the Endonuclease virus is unlikely to saturate all available CD81 receptors. We found the effect of anti-CD81 on

IL-2 expression to be dose-dependent. The degree of cross-linking may also be influenced by the size of viral particles (45-60 nm) relative to lymphocytes (6-8 μm), which together with the affinity and avidity of E2 for CD81 will be factors in how ligation of CD81 (alone or in combination with CD3) can modulate levels of IL-2 expression/secretion. HCV E2-CD81 interaction stimulates the translocation of PKCβ from the cytosol to lipid raft subdomains of the cell membrane. Lipid rafts are specific membrane compartments composed of cholesterol, glycolipids, and protein, which host receptors and signaling molecules involved in different cellular events, including cell signaling, pathogen invasion, and immune responses.34 PKCβ sequestration in lipid rafts prevented its association with the centrosome and the cellular secretory machinery necessary for IL-2 secretion in a process reversible by lipid raft disruption.