Induction of IgA and sustained deficiency of cell proliferative response in chronic hepatitis C

Protective T Cell and Antibody Immune Responses against Hepatitis C Virus Achieved Using a Biopolyester-Bead-Based Vaccine Delivery System

Hepatitis C virus (HCV) infection is a major worldwide problem. Chronic hepatitis C is recognized as one of the major causes of cirrhosis, hepatocellular carcinoma, and liver failure. Although new, directly acting antiviral therapies are suggested to overcome the low efficacy and adverse effects observed for the current standard of treatment, an effective vaccine would be the only way to certainly eradicate HCV infection. Recently, polyhydroxybutyrate beads produced by engineered Escherichia coli showed efficacy as a vaccine delivery system. Here, an endotoxin-free E. coli strain (ClearColi) was engineered to produce polyhydroxybutyrate beads displaying the core antigen on their surface (Beads-Core) and their immunogenicity was evaluated in BALB/c mice. Immunization with Beads-Core induced gamma interferon (IFN-γ) secretion and a functional T cell immune response against the HCV Core protein. With the aim to target broad T and B cell determinants described for HCV, Beads-Core mixed with HCV E1, E2, and NS3 recombinant proteins was also evaluated in BALB/c mice. Remarkably, only three immunization with Beads-Core+CoE1E2NS3/Alum (a mixture of 0.1 μg Co.120, 16.7 μg E1.340, 16.7 μg E2.680, and 10 μg NS3 adjuvanted in aluminum hydroxide [Alum]) induced a potent antibody response against E1 and E2 and a broad IFN-γ secretion and T cell response against Core and all coadministered antigens. This immunological response mediated protective immunity to viremia as assessed in a viral surrogate challenge model. Overall, it was shown that engineered biopolyester beads displaying foreign antigens are immunogenic and might present a particulate delivery system suitable for vaccination against HCV.

Neutralizing antibodies and broad, functional T cell immune response following immunization with hepatitis C virus proteins-based vaccine formulation

HCV is a worldwide health problem despite the recent advances in the development of more effective therapies. No preventive vaccine is available against this pathogen. However, non-sterilizing immunity has been demonstrated and supports the potential success of HCV vaccines. Induction of cross-neutralizing antibodies and T cell responses targeting several conserved epitopes, have been related to hepatitis C virus (HCV) clearance. Therefore, in this work, the immunogenicity of a preparation (MixprotHC) based on protein variants of HCV Core, E1, E2 and NS3 was evaluated in mice and monkeys. IgG from MixprotHC immunized mice and monkeys neutralized the infectivity of heterologous HCVcc. Moreover, strong CD4+ and CD8+ T cells proliferative and IFN-γ secretion responses were elicited against HCV proteins. Remarkably, immunization with MixprotHC induced control of viremia in a surrogate challenge model in mice. These results suggest that MixprotHC might constitute an effective immunogen against HCV in humans with potential for reducing the likelihood of immune escape and viral persistence.

HCV-specific immune responses induced by CIGB-230 in combination with IFN-α plus ribavirin

AIM: To analyze hepatitis C virus (HCV)-specific immune responses in chronically infected patients under triple therapy with interferon-α (IFN-α) plus ribavirin and CIGB-230.

METHODS: CIGB-230 was administered in different schedules with respect to IFN-α plus ribavirin therapy. Paired serum and peripheral blood mononuclear cells (PBMC) samples from baseline and end of treatment were analyzed. The HCV-specific humoral response was tested by enzyme-linked immunosorbent assay, neutralizing antibodies were evaluated by cell culture HCV neutralization assays, PBMC proliferation was assayed by carboxyfluorescein succinimidyl ester staining and IFN-γ secretion was assessed by enzyme-linked immunospot. Data on virological and histological response and their association with immune variables are also provided.

RESULTS: From week 12 to week 48, all groups of patients showed a significant reduction in mean leukocyte counts. Statistically significant reductions in antibody titers were frequent, but only individuals immunized with CIGB-230 as early add-on treatment sustained the core-IgG response, and the neutralizing antibody response was enhanced only in patients receiving CIGB-230. Cell-mediated immune responses also tended to decline, but significant reductions in IFN-γ secretion and total absence of core-specific lymphoproliferation were exclusive of the control group. Only CIGB-230-immunized individuals showed de novo induced lymphoproliferative responses against the structural antigens. Importantly, it was demonstrated that the quality of the CIGB-230-induced immune response depended on the number of doses and timing of administration in relation to the antiviral therapy. Specifically, the administration of 6 doses of CIGB-230 as late add-on to therapy increased the neutralizing antibody activity and the de novo core-specific IFN-γ secretion, both of which were associated with the sustained virological response.

CONCLUSION: CIGB-230, combined with IFN-α-based therapy, modifies the immune response in chronic patients. The study provides evidence for the design of more effective therapeutic vaccine interventions against HCV.

Serum cytokine profile in hepatitis C virus carriers presenting cryoglobulinaemia and non-organ-specific autoantibodies

This work investigated the serum cytokine profile (IL-2, IL-4, IL-5, IL-10, IFN-gamma and BAFF) of hepatitis C virus (HCV) carriers with autoimmunity. Forty-seven HCV carriers and 28 healthy controls were evaluated. Cytokine levels were measured by ELISA. Patients and controls presented similar levels of IL-2, IL-4, IL-5, IL-10, IFN-gamma and BAFF (p>0.05). Cryoglobulinaemic HCV carriers had increased IL-2 (p=0.013), IL-5 (p=0.018) and BAFF (p=0.050). IFN-gamma level was decreased in HCV carriers with rheumatoid factor in comparison with those that were RF-seronegative (p=0.035). Patients with beta2GPI IgA antibodies when were compared with those without this autoantibody, had more serum IL-2 (p=0.009), IL-5 (p=0.018) and BAFF (p=0.039). Interleukin-2 was increased in HCV carriers with positive ANA when they were compared with ANA-seronegative carriers (p=0.044). Interleukins IL-4 and IL-10 were not associated with autoimmunity (P>0.05). In HCV carriers, IL-2 was correlated with IL-5 (p<0.0001) and IFN-gamma (p=0.015), and IL-5 with IFN-gamma (p=0.015). We concluded that the serum profile of cytokines in HCV carriers presenting autoimmune markers may be mainly represented by increased IL-2, IL-5 and BAFF.