Identification of a murine CD4+ T-lymphocyte response site in hepatitis C virus core protein

Induction of multispecific Th-1 type immune response against HCV in mice by protein immunization using CpG and Montanide ISA 720 as adjuvants

Recent studies demonstrate that Th1-type immune responses against a broad spectrum of hepatitis C virus (HCV) gene products are crucial to the resolution of acute HCV infection. We investigated new vaccine approaches to augment the strength of HCV-specific Th1-type immune responses. ELISPOT assay revealed that single or multiple protein immunization using both CpG ODN and Montanide ISA 720 as adjuvants induced much stronger IFN-gamma-producing Th1 responses against core, NS3 and NS5b targets than did the formulation without these adjuvants. Protein vaccination using CpG ODN and Montanide ISA 720 as adjuvants also greatly enhanced humoral responses to HCV core, E1/E2 and NS3. When specific IgG isotypes were assayed, protein immunization using CpG ODN and Montanide ISA 720 as adjuvants produced higher titers of IgG2a dominant antibodies than did protein immunization alone, indicating a more Th1-biased pathway. This increase in IgG2a is consistent with the induction of Th1 cells secreting IFN-gamma demonstrated by ELISPOT assay. In conclusion, protein immunization using CpG ODN and Montanide ISA 720 as adjuvants greatly enhanced cellular (Th1 type) as well as humoral immune responses against HCV in Balb/c mice. The use of adjuvants appears critical to the induction of Th1 immune responses during HCV vaccination with recombinant proteins.

Comparison of antibody- and cell-mediated immune responses after intramuscular hepatitis C immunizations of BALB/c mice

Current treatments for hepatitis C infection have limited efficacy, and there is no vaccine available. The goal of this study was to compare the immune response to several immunization combinations against hepatitis C virus (HCV). Six groups of mice were immunized at weeks 0, 4, and 8 with different combinations of a candidate HCV vaccine consisting of 100 microg recombinant HCV core/E1/E2 (rHCV) DNA plasmid and/or 25 microg rHCV polyprotein and 50 microL Montanide ISA- 51. Four weeks after the last injection, all groups of mice were sacrificed and blood samples and spleens were collected for measuring the levels of specific HCV antibodies (total IgG, IgG1, and IgG2a). Cell proliferation and intracellular interferon-gamma were also measured. Among the groups of immunized mice, only the mice immunized with rHCV DNA plasmid, rHCV polyprotein, and montanide (group D) and mice immunized with rHCV polyprotein and montanide (group F) demonstrated a significant increase in the total IgG titer after immunization. IgG1 was the predominant antibody detected in both groups D and F. No IgG2a was detected in any of the groups. Proliferation assays demonstrated that splenocytes from group D and group C (rHCV DNA primed/rHCV polyprotein boost) developed significant anti-HCV proliferative responses. The combination of an rHCV DNA plasmid, rHCV polyprotein, and montanide induced a high antibody titer with a predominance of IgG1 antibodies and recognized the major neutralization epitopes in HVR1. In contrast, group C did not show an increase in anti-HCV antibodies, but did show a proliferative response.

Clinically Related Protein–Peptide Interactions Monitored in Real Time on Novel Peptide Chips by Surface Plasmon Resonance Imaging

Background: Developing rapid, high-throughput assays for detecting and characterizing protein–protein interactions is a great challenge in the postgenomic era. We have developed a new method that allows parallel analysis of multiple analytes in biological fluids and is suitable for biological and medical studies.

Methods: This technology for studying peptide–antibody interactions is based on polypyrrole-peptide chips and surface plasmon resonance imaging (SPRi). We generated a chip bearing a large panel of peptide probes by successive electro-directed copolymerizations of pyrrole–peptide conjugates on a gold surface.

Results: We provide evidence that (a) the signal produced by antibody binding is highly specific; (b) the detected signal specifically reflects the antibody concentration of the tested solution in a dose-dependent manner; (c) this technique is appropriate for analyzing complex media such as undiluted sera, a novelty with respect to previous techniques; and (d) correlation between classic ELISA results and the SPRi signal is good (P = 0.008). We also validated this system in a medical model by detecting anti-hepatitis C antibodies in patient-derived sera.

Conclusion: Because of its characteristics (easy preparation of the peptide chip; high-throughput, label-free, real-time detection; high specificity; and low background), this technology is suitable for screening biological samples and for large-scale studies.

Quantitative analysis of anti-hepatitis C virus antibody-secreting B cells in patients with chronic hepatitis C

To investigate the quantitative characteristics of humoral immunity in patients with hepatitis C, we established an enzyme-linked immunosorbent spot (ELISpot) assay for detection of anti-hepatitis C virus (HCV)-secreting B cells. Receiver operating characteristic curve analysis demonstrated 100% specificity and 58% to 92% sensitivity for detecting B-cell responses to NS5b, NS3, E2, and core antigens. The median sum of anti-HCV-secreting B cells to all HCV antigens tested was significantly higher in 39 patients with chronic hepatitis C (47.3 spot forming cells [SFCs]/10(6) peripheral blood mononuclear cells [PBMCs]) than in 9 recovered subjects (15.3 SFCs/10(6) PBMCs; P = .05) or 11 uninfected controls (5.3 SFCs/10(6) PBMCs; P < .001); the significant difference (P = .018) in chronic versus recovered patients was in reactivity to nonstructural antigens NS3 and NS5b. Anti-HCV immunoglubulin M (IgM)-secreting B cells were also readily detected and persisted decades into HCV infection; there was no difference in IgM-positive cells between chronic and recovered patients. ELISpot reactivity to genotype 1-derived antigens was equivalent in patients of genotypes 1, 2, and 3. There was significant correlation between the numbers of anti-HCV IgG-secreting B cells and serum aminotransferase and to the level of circulating antibody. In conclusion, ELISpot assays can be adapted to study B-cell as well as T-cell responses to HCV. Measurement at the single-cell level suggests that humoral immunity plays a minor role in recovery from HCV infection and that B-cell immunity is strongest in those with persistent infection.

Effects of Distinct Adjuvant on HCV DNA Vaccine at Different Dosages

AIM: To explore the effects of different adjuvants on different dosages of hepatitis C virus (HCV) DNA vaccine.

METHODS: Female Balb/c mice were primed by HCV DNA vaccine composed of HCV structure gene DNA, HCV nonstructure gene 3 (NS3) and NS5b at the dosages of either 100 mg/each or 50mg/each with liposome DDAB/EPC or aluminum hydroxide and boosted twice accordingly. The cytokine profiles induced by various HCV antigens on splenocytes from the immunized mice were assessed by ELISPOT assay using in vitro splenocyte culture stimulated with recombinant HCV core, E2, E1/E2, NS3 or NS5b protein.

RESULTS: The frequency of IFN-g or IL-4 secreting cells found in splenocytes stimulated with HCV core, E2, or E1/E2 from the mice vaccinated with HCV recombinant DNA in DDAB/EPC adjuvant was significantly higher (P<0.05) than that from mice immunized with either naked DNA or DNA formulated in aluminum hydroxide. The frequency of IL-4 secreting cells from mice immunized with HCV DNA at a dosage of 100 mg/each mixed with aluminum hydroxide was significantly higher than that from naked DNA when the splenocytes were stimulated with all the antigens tested except E2 (P<0.05). At many cases, lymphocytes from mice received 100 mg/each DNA have more IFN-g or IL-4 productions compared with those from mice with 50 mg/each (P<0.05). The lymphocytes from mice primed and boosted with HCV DNA plus aluminum hydroxide can produce more IL-4 than IFN-g in contrast with the cytokine profile of mice immunized with naked DNA or DDAB/EPC adjuvant.

CONCLUSION: Liposome DDAB/EPC has strong adjuvant effects on HCV DNA vaccine. Aluminum hydroxide is a Th2 adjuvant and can convert the Th1 nature of DNA vaccine to Th2-biased immunity. It seems that the dosage of 50 mg of HCV DNA vaccine is not adequate to elicit efficient immunity in mice.