An autoimmune domain-reduced HCV core gene remains effective in stimulating anti-core cytotoxic T lymphocyte activity

Abstract

Chronic hepatitis C virus (HCV) infection cases resistant to conventional therapies might be treated by immunotherapy as cytotoxic T lymphocytes (CTL) are the main mechanism through which viral infections are cleared. The HCV core gene, with the highest homology between HCV types, deleted of its autoimmune-stimulating regions (pseudo-GOR and pseudo-p450), may be an appropriate antigen for targeting HCV-infected cells. Two recombinant adeno-associated virus (rAAV) vectors, carrying either the full length (aa 1-190) or truncated (aa 49-180, deleted of the pseudo-GOR and pseudo-p450 sequences) versions of core, were generated. Both AAV/core (l-190) and AAV/core (49-180) were used to transduce/load dendritic cells (DC) at high levels (88-95%). These two genetically altered DC types then stimulated anti-core CTL. The DC and CTL were analyzed by FACS and for killing efficiency (percent target killing). The rAAV-altered DC displayed higher levels of CD80, CD83, CD86, and CD 1a than control DC. The truncated core (aa 49-180) gene stimulated equivalent and strong killing of synthetic core-positive autologous peripheral blood lymphocyte (PBL) targets to that stimulated by the full length core gene. However, the smaller core (49-180) antigen gene stimulated lower levels of killing of core-negative "self" PBL targets (GOR- and p450-positive) (p = 0.002). These AAV/core: DC-stimulated CTL displayed higher IFN-gamma expression, higher CD8:CD4 ratios, and lower CD56:CD8 ratios than controls. The rAAV-loading derived CD8+ T cells had more CD69+ cells and the CD4+ T populations had fewer CD25+ cells than controls. We conclude that the core (49-180) gene is an effect antigen, but has the advantage of stimulating less self-recognition. Thus, core (49-180) may be useful for further translational immunotherapy studies against HCV.