Neurotoxic effects of the HCV core protein are mediated by sustained activation of ERK via TLR2 signaling.

Hepatitis C virus (HCV) infection is a serious problem among those co-infected with human immunodeficiency virus; however, its impact in the central nervous system (CNS) remains unclear. This study aimed to investigate the mechanisms underlying HCV core protein-mediated neurodegeneration. Analysis of human HCV seropositive cases demonstrated widespread damage to neuronal dendritic processes and sustained activation of extracellular signal-related kinase (ERK); analogous pathologies were observed in wild type injected with HCV core protein into the hippocampus. In vitro analysis in neuronal cells exposed to HCV core demonstrated retraction of the neuronal processes in an ERK/Signal Transducer and Activator of Transcription 3 (STAT3)-dependent manner dependent on toll-like receptor 2 (TLR2) signaling activation. These results indicate that HCV core protein neurotoxicity may be mediated by the sustained activation of ERK/STAT3 via TLR2-IRAK1 signaling pathway. These pathways provide novel targets for development of neuroprotective treatments for HCV involvement of the CNS.

Attenuated Listeria monocytogenes vaccine vectors expressing influenza A nucleoprotein: preclinical evaluation and oral inoculation of volunteers.

Listeria monocytogenes vectors have shown promise for delivery of viral and tumor antigens in animals. We used two mutant vector strains deleted for actA/plcB (BMB72) and actA/inlB (BMB54), and engineered both strains to secrete a heterologous nucleoprotein antigen from the Influenza A virus. Strains were evaluated in vitro and in mice. Twenty-two healthy volunteers received single oral doses of either strain in a physiological study of safety, shedding, and immunogenicity. Volunteers were observed in the hospital for seven days and had daily blood cultures, routine safety blood tests (complete blood count with differential; hepatic and renal function), and fecal cultures; none had fever, positive blood cultures, prolonged shedding, or serious or unexpected events. Four of 12 volunteers who received the actA/plcB-deleted strain had minor, transient, asymptomatic serum transaminase elevations (maximum increase 1.4× upper normal). Six of six volunteers who received ≥4 × 10(9) colony forming units had detectable mucosal immune responses to listerial antigens, but not to the vectored influenza antigen. Approximately half the volunteers had modest interferon-γ ELISpot responses to a complex listerial antigen, but none had increases over their baseline responses to the influenza antigen. Comparison with prior work suggests that foreign antigen expression, and perhaps also freezing, may adversely affect the organisms' immunogenicity.

Priming of CD4+ and CD8+ T cell responses using a HCV core ISCOMATRIX vaccine: a phase I study in healthy volunteers.

The disease burden and public health impact of chronic HCV infection continues to be a major problem globally. Current treatment for chronic HCV infection is not effective in all patients and is frequently associated with unacceptable side effects. Clearly a need exists for improved treatments and one such strategy is the use of therapeutic vaccines. Although still not completely understood, emerging data indicate that the generation of CD4(+) and CD8(+) T cells are important for the clearance of HCV. We have developed a prototype vaccine with the HCV Core protein and ISCOMATRIX adjuvant (HCV Core ISCOMATRIX vaccine). ISCOMATRIX vaccines have been shown to induce CD4(+) and CD8(+) T cell responses to a range of antigens in both animal models and in human studies. Additionally, ISCOMATRIX vaccines have been shown to be safe and generally well tolerated in several clinical trials. Preliminary studies demonstrated that the prototype HCV Core ISCOMATRIX vaccine induced strong CD4(+) and CD8(+) T cell responses in monkeys following immunization. Here we show the results of a Phase I placebo controlled, dose escalation clinical study designed to evaluate the safety, tolerability and immunogenicity of the HCV Core ISCOMATRIX vaccine in healthy individuals. The 30 subjects received three immunizations of HCV Core ISCOMATRIX vaccines or placebo vaccine on days 0, 28 and 56. The HCV Core ISCOMATRIX vaccines contained 5, 20 or 50 microg HCV Core protein with 120 mug ISCOMATRIX adjuvant. The adverse events reported were generally mild to moderate in severity, of short duration and self-limiting. The most common adverse events were injection site reactions such as pain and redness as well as myalgia. Antibody responses were detected in all but one of the participants receiving the HCV Core ISCOMATRIX vaccine and there was no indication of a dose response. CD8(+) T cell responses were only detected in two of the eight participants receiving the highest dose. T cell cytokines were detected in 7 of the 8 participants in the highest dose group. The results of this study support the further evaluation of this prototype HCV Core ISCOMATRIX vaccine in HCV infected subjects.