HCV-specific Immune Responses Research Articles

Immunization with hepatitis C virus-like particles protects mice from recombinant hepatitis C virus-vaccinia infection.

We have recently demonstrated that immunization with hepatitis C virus-like particles (HCV-LPs) generated in insect cells can elicit both humoral and cellular immune responses in BALB/c mice. Here, we evaluate the immunogenicity of HCV-LPs in HLA2.1 transgenic (AAD) mice in comparison to DNA immunization. HCV-LP immunization elicited a significantly stronger humoral immune response than DNA immunization. HCV-LP-immunized mice also developed stronger HCV-specific cellular immune responses than DNA-immunized mice as determined by using quantitative enzyme-linked immunospot (ELISpot) assay and intracellular cytokine staining. In BALB/c mice, immunization with HCV-LPs resulted in a >5 log10 reduction in vaccinia titer when challenged with a recombinant vaccinia expressing the HCV structural proteins (vvHCV.S), as compared to 1 log10 decrease in DNA immunization. In HLA2.1 transgenic mice, a 1-2 log10 reduction resulted from HCV-LP immunization, whereas no reduction was seen from DNA immunization. Adoptive transfer of lymphocytes from HCV-LP-immunized mice to naive mice provided protection against vvHCV.S challenge, and this transferred immunity can be abrogated by either CD4 or CD8 depletion. Our results suggest that HCV-LPs can induce humoral and cellular immune responses that are protective in a surrogate HCV challenge model and that a strong cellular immunity provided by both CD4 and CD8 effector lymphocytes may be important for protection from HCV infection.

The clearance of hepatitis C virus infection in chimpanzees may not necessarily correlate with the appearance of acquired immunity.

Clearance of hepatitis C virus (HCV) infection in humans and chimpanzees is thought to be associated with the induction of strong T-cell responses. We studied four chimpanzees infected with HCV derived from an infectious full-length HCV genotype 1b cDNA. Two of the chimpanzees cleared the infection to undetectable levels for more than 12 months of follow-up; the other two became persistently infected. Detailed analyses of HCV-specific immune responses were performed during the courses of infection in these chimpanzees. Only weak and transient T helper responses were detected during the acute phase in all four chimpanzees. A comparison of the frequency of gamma interferon (IFN-gamma)-producing CD4(+) and CD8(+) T cells in peripheral blood by ELISpot assay did not reveal any correlation between viral clearance and T-cell responses. In addition, analyses of IFN-gamma, IFN-alpha, and interleukin-4 mRNA levels in liver biopsies, presumably indicative of intrahepatic T-cell responses, revealed no distinct pattern in these chimpanzees with respect to infection outcome. The present study suggests that the outcome of HCV infection in chimpanzees is not necessarily attributable to HCV sequence variation and that chimpanzees may recover from HCV infection by mechanisms other than the induction of readily detectable HCV-specific T-cell responses.

111 HCV-specific cellular immune responses in subjects who are antiHCV-negative, HCV RNA-negative despite longterm (>15 years) injection drug use

111 HCV-specific cellular immune responses in subjects who are antiHCV-negative, HCV RNA-negative despite longterm (>15 years) injection drug use

221 HCV-specific immune responses at baseline do not predict virologic response to antiviral therapy in advanced hepatitis C

221 HCV-specific immune responses at baseline do not predict virologic response to antiviral therapy in advanced hepatitis C

65 Induction of HCV-specific immune responses by hepatitis C virus-like particles in non-human primates: implications for prevention and therapy of hepatitis C

65 Induction of HCV-specific immune responses by hepatitis C virus-like particles in non-human primates: implications for prevention and therapy of hepatitis C

Oral lichen planus pathogenesis: A role for the HCV-specific cellular immune response

Hepatitis C virus infection can be associated with different extrahepatic manifestations, including lichen planus; however, no clear role for HCV in their pathogenesis has been established. T cells were isolated from lichen biopsy specimens of 7 HCV positive patients with oral lichen planus. HCV-specific CD4+ T-cell lines were obtained in 4 patients from lichen lesions but only in 2 of them from the peripheral blood. Different clonal populations were found in oral tissue and peripheral blood of individual patients, as shown by TCR-Vβ analysis of antigen-specific T cells. Frequency of HCV-specific CD8+ cells tested with 4 different HCV tetramers was significantly higher in the lichen tissue than in the circulation; moreover, lichen-derived HCV-specific CD8+ T cells showed the phenotype of recently activated T cells because most of them were CD69+ and produced interferon gamma (IFN-γ) but expanded poorly in vitro upon antigen stimulation. The specificity of HCV-reactive T-cell recruitment into the lichen tissue was further confirmed by the absence of HBV-specific T cells within lichen lesions in 3 additional patients with lichen planus associated with HBV infection. Our study shows HCV-specific T-cell responses at the site of the lesions of an HCV-associated dermatologic disease, sustained by HCV-specific T cells with phenotypic and functional characteristics of terminally differentiated effector cells. In conclusion, this finding and the detection of HCV RNA strands in the lichen tissue strongly suggest a role for HCV-specific T-cell responses in the pathogenesis of oral lichen planus associated with HCV infection. (HEPATOLOGY2002;36:1446–1452).

Oral lichen planus pathogenesis: A role for the HCV-specific cellular immune response

Hepatitis C virus infection can be associated with different extrahepatic manifestations, including lichen planus; however, no clear role for HCV in their pathogenesis has been established. T cells were isolated from lichen biopsy specimens of 7 HCV positive patients with oral lichen planus. HCV-specific CD4 + T-cell lines were obtained in 4 patients from lichen lesions but only in 2 of them from the peripheral blood. Different clonal populations were found in oral tissue and peripheral blood of individual patients, as shown by TCR-Vβ analysis of antigen-specific T cells. Frequency of HCV-specific CD8 + cells tested with 4 different HCV tetramers was significantly higher in the lichen tissue than in the circulation; moreover, lichen-derived HCV-specific CD8 + T cells showed the phenotype of recently activated T cells because most of them were CD69 + and produced interferon gamma (IFN-γ) but expanded poorly in vitro upon antigen stimulation. The specificity of HCV-reactive T-cell recruitment into the lichen tissue was further confirmed by the absence of HBV-specific T cells within lichen lesions in 3 additional patients with lichen planus associated with HBV infection. Our study shows HCV-specific T-cell responses at the site of the lesions of an HCV-associated dermatologic disease, sustained by HCV-specific T cells with phenotypic and functional characteristics of terminally differentiated effector cells. In conclusion, this finding and the detection of HCV RNA strands in the lichen tissue strongly suggest a role for HCV-specific T-cell responses in the pathogenesis of oral lichen planus associated with HCV infection. (H EPATOLOGY 2002;36:1446-1452.)

Association of increased hepatitis C virus (HCV)-specific IgG and soluble CD26 dipeptidyl peptidase IV enzyme activity with hepatotoxicity after highly active antiretroviral therapy in human immunodeficiency virus-HCV-coinfected patients.

Hepatotoxicity was investigated, using plasma collected before and during treatment, in 16 human immunodeficiency virus (HIV)-hepatitis C virus (HCV)-coinfected patients who responded to highly active antiretroviral therapy (HAART), during a retrospective longitudinal study. Eleven patients experienced hepatotoxicity (i.e., a >3-fold increase in alanine aminotransferase level) while receiving HAART, including 4 patients with clinical hepatitis. Control subjects were 5 patients without hepatotoxicity. Markers of HCV-specific immune responses (HCV core-specific immunoglobulin G [IgG] antibody), T cell activation (soluble [s] CD26 dipeptidyl peptidase IV [DPP IV] enzyme activity), and inflammation (nitrate/nitrite and soluble tumor necrosis factor receptor I [sTNFRI] levels) were correlated with liver damage and immune reconstitution. All patients with hepatotoxicity had increased HCV core-specific IgG antibody and sCD26 (DPP IV) activity but did not have increased nitrate/nitrite or sTNFRI levels. Hepatotoxicity without clinical hepatitis was associated with increased CD8 T cell counts. Thus, hepatotoxicity in HIV-HCV-coinfected patients who respond to HAART is associated with increased HCV-specific immune responses and T cell activation.

Priming of hepatitis C virus-specific cytotoxic T lymphocytes in mice following portal vein injection of a liver-specific plasmid DNA.

The immunology of hepatitis C virus (HCV) infection should be studied in the context of HCV antigen expression in the liver, because HCV primarily infects this organ. Indeed, the nature, function, and fate of T cells primed after antigen expression in the liver might differ from those primed when antigens are expressed systemically or in other organs, because the nature of the antigen-presenting cells (APCs) involved may be different. In addition, the normal liver contains a resident population of lymphocytes that differ from those present at other sites. Thus, we investigated whether HCV-specific CD8(+) cytotoxic T cells (CTLs) could be elicited following portal vein (PV) injection of plasmid DNA in mice whose hepatic veins were transiently occluded. We show that PV injection of mice with "naked" DNA expressing the HCV-NS5a protein, under the control of a liver-specific enhancer/promoter, resulted in NS5a expression in the liver and the priming of HCV-specific CTLs. These results suggested that such a model might be relevant to the study of HCV-specific immune responses primed during natural infection.

Characterization of HCV-specific cellular and humoral immune responses referred to virus elimination

Characterization of HCV-specific cellular and humoral immune responses referred to virus elimination

The antiviral compound ribavirin modulates the T helper (Th) 1/Th2 subset balance in hepatitis B and C virus-specific immune responses.

Ribavirin is effective in combination therapies against chronic hepatitis C virus (HCV) infection, although its direct antiviral properties are unclear. We therefore studied the immune-modulatory effects of ribavirin on hepatitis B virus (HBV)- and HCV-specific immune responses. During a 24 week placebo-controlled ribavirin trial in ten patients with chronic HCV infection, HCV antibodies and alanine aminotransferase (ALT) levels decreased transiently whereas the serum levels of HCV RNA remained stable. Effects of ribavirin on human and murine phytohaemagglutinin (PHA)-activated T cells included inhibition of in vitro proliferation and modulation of IL-2, IL-4, IFN-gamma and TNF-alpha levels. HBcAg- and HBeAg-specific IL-2 and IFN-gamma levels were > or = 25-fold higher in mice immunized with HBV core- or e-antigens (HBcAg, HBeAg) while receiving ribavirin compared to untreated mice, but IL-4 and IL-6 remained constant. Concordantly, a slight shift was observed in the IgG subclass distribution of the humoral responses of ribavirin-treated mice to HBeAg and HCV NS3 protein. Ribavirin treatment of HBeAg-transgenic (HBeAg-Tg) mice induced a dose-dependent down-regulation of T helper (Th)2-mediated antibody production to HBeAg. In ribavirin-treated HBeAg-Tg mice anti-HBe IgG1 (positively regulated by Th2 cytokines) decreased simultaneously as both anti-HBe IgG2a (positively regulated by Th1 cytokines) levels and in vitro T-cell IFN-gamma production increased, indicating a change in the Th1/Th2 balance. Thus, the present data suggest that ribavirin is not strictly an antiviral compound, but rather it alters the T-cell balance in the immune system.

Enhancement of cellular and humoral immune responses to hepatitis C virus core protein using DNA-based vaccines augmented with cytokine-expressing plasmids.

Development of a broad based cellular and humoral immune response to hepatitis C virus (HCV) structural proteins may be important for irradication of infection. DNA-based immunization is a promising approach to generate HCV-specific immune responses. Previous studies of DNA-based immunizations in mice using an HCV core DNA expression plasmid (pHCV2-2) demonstrated an efficient CTL response against HCV core epitopes; however, the humoral and Th cell proliferative responses were found to be weak. To enhance the immunogenicity of this nonsecreted viral structural protein at the B and T cell level, we coimmunized mice with pHCV2-2 and DNA expression constructs encoding for mouse IL-2, IL-4, and granulocyte-macrophage CSF proteins. Under these experimental conditions, a seroconversion frequency to anti-HCV core increased from 40 to 80% in immunized mice. The CD4+ inflammatory T cell proliferative responses as well as CD8+ CTL activity to HCV core protein were enhanced substantially after coimmunization with the IL-2 and granulocyte-macrophage CSF DNA expression constructs. In contrast, coimmunization with an IL-4-producing construct induced differentiation of Th cells toward a Th0 subtype and suppressed HCV core-specific CTL activity. Taken together, these studies emphasize that generation of antiviral immune responses using DNA-based immunization may be modified by local cytokine production at the site of Ag presentation.