Functional measurement of hepatitis C virus core-specific CD8(+) T-cell responses in the livers or peripheral blood of patients by using autologous peripheral blood mononuclear cells as targets or stimulators

The evaluation of hepatitis C virus core antigen in immunized BALB/c mice

BACKGROUND

Hepatitis infection represents one of the important causes of morbidity and mortality in developing countries, however there is not any effective vaccine against hepatitis C which is one of the significant problems in vaccine project.

OBJECTIVES

The aim of the present study is to evaluate the role of HCV core protein in inducing IFN-Gamma secretion and TCL activities as a vaccine in Balb/C mice.

MATERIAL AND METHODS

Our previous cloned plasmid (HCV Core gene into pETDuet-1) applied for protein expression in bacteria. The expressed and purified recombinant protein together with Freund's adjuvant was injected to 15 Balb/c mice. The total IgG and IgG2a of immunized mice sera were evaluated after a week. Two weeks after booster injection, we studied the proliferation and IFNγ secretion of spleens, inguinal and popliteal lymph nodes lymphocytes by ELISA and ELISPOT.

RESULTS

The FSFC (Frequency of spot forming cells) of secreting cells of immunized mice with HCV/Core protein and sera IgG2a were considerably higher than the control groups.

CONCLUSIONS

The core protein together with proper adjuvant can be a candidate vaccine against of HCV infection.

Hepatitis C lipo-Viro-particle from chronically infected patients interferes with TLR4 signaling in dendritic cell

Background

Hepatitis C virus (HCV) can be purified from serum of chronically-infected patients in the form of Lipo-Viro-Particles (LVP), which are triglycerid-rich lipoprotein-like particles containing viral RNA and proteins. Since LVP is a constant feature of chronically infected patients, we asked whether purified LVP could interfere with the immune response by acting directly on dendritic cell (DC) function.

Methods and Findings

We have analyzed the impact of LVP on the maturation monocyte-derived DC induced by TLR3 or TLR4 ligands. Following incubation with LVP, immature DC supported weak transient HCV-RNA replication and type I IFN synthesis. This, however, did not lead to viral particle production nor to maturation of DC. LVP-treatment prior to TLR3 stimulation by polyI:C only enhanced the secretion of IL-12, IL-6 and TNFα yielding typical mature DC. In contrast, LVP-treated DC activated by the TLR4 ligand LPS yielded phenotypically mature DC with reduced capacity to secrete both pro- and anti-inflammatory cytokines. Their ability to stimulate allogeneic T lymphocytes was strongly affected since activated T cells produced IL-5 and IL-13 instead of IFNγ. Addition of IFNα prevented the effect of LVP on DC function. Restoration of IFNγ secretion by T cells was obtained by blocking ERK activation in DC, while induction of IL-5 and IL-13 secretion was inhibited by blocking the p38-MAPK pathway in DC.

Conclusions

LVP can interfere with TLR4-triggered maturation of DC, inducing a shift in DC function that stimulates Th2 cells instead of Th1, by a mechanism that is ERK- and p38-MAPK-dependent. The effect of LVP on DC polarization was reversed by IFNα, providing an additional rationale for the interferon therapy of chronically-infected patients. By acting on TLR4 pathway with LVP, HCV may thus exploit a natural protective mechanism of the liver and the intestine normally used to control inflammation and immunity to commensal microorganisms.

Differential effects of synthesized 2′-oxygenated chalcone derivatives: modulation of human cell cycle phase distribution

Ten structurally related 2'-oxygenated chalcone derivatives, bearing either hydroxy and/or methoxy substituents on the A and B rings, were synthesized through Claisen-Schmidt condensation. The synthesis procedure was relatively easy and had an acceptable yield. The in vitro cytotoxicities of these compounds against the human tumor cells such as Jurkat, U937 cells, and normal cells PHA stimulated PBMCs were investigated. Among those, compounds 1 (IC50 = 2.5 microM), 2 (1.7 microM), and 8 (3.2 microM) showed potent inhibitory activity toward Jurkat cell line. In parallel, compounds 1 (6.7 microM), 2 (1.5 microM), and 10 (5.3 microM) showed the highest activity against U937 cell line. However, the chalcones also inhibit the PHA stimulated PBMCs cells, but the IC50 values were relatively high when compared to the tumor cell line values. Studies were also on the effect of synthesized chalcones on the cell cycle phase distribution. In Jurkat cell line, compounds 7 and 9 showed the highest activity and the most striking effect in reduction of the percentage of cells in the S phase, which was associated with an increase of cells in G2/M phase. In U937 cell line, compound 3 increased the proportion of cells in the G0/G1 phase and reduced the proportion in S phase. In contrast, compounds 1, 9, and 10 showed a decrease effect on the percentage of cells in S phase and an increase effect on the percentage of cells in the G2/M phase of the cell cycle. Whereas in the case of PHA stimulated PBMCs, compounds 1, 4, 8, and 10 increased the percentage of cells in G2/M phase, which was associated with a decrease effect in the S phase of the cell cycle.

Ribavirin and interferon is effective for hepatitis C virus clearance in hepatitis B and C dually infected patients

Ribavirin and interferon (IFN) are an effective treatment in 30% to 60% of patients with chronic hepatitis C. Whether they are also effective in dually infected patients with hepatitis B and C is unknown. Twenty-four patients with chronic hepatitis seropositive for both hepatitis B surface antigen and antibody to HCV received ribavirin 1,200 mg daily for 6 months, together with 6 million units (MU) IFN-alpha 2a thrice weekly for 12 weeks and then 3 MU for another 12 weeks. Serum HCV RNA was positive in 21 patients (group I, serum HBV DNA positive in 17 patients) and negative in 3 patients (group II, all HBV DNA positive) by Amplicor (Cobas Amplicor Monitor, Roche Diagnostics, Branchburg, NJ). Serum alanine aminotransferase (ALT), HCV RNA, and hepatitis B virus (HBV) DNA were monitored regularly for 12 months. Another 30 patients with chronic hepatitis C alone receiving the same regimen, served as controls. The serum HCV clearance rate in group I patients (43%) was comparable with that in controls (60%, P =.63) 24 weeks posttreatment. The serum ALT normalization rate in group I and group II patients was 43% and 0%, respectively, 24 weeks posttreatment. After treatment, resurgence of HBV and HCV was encountered in 4 group I patients and 1 group II patient, respectively. In conclusion, in hepatitis B and C dually infected patients, combination of IFN with ribavirin can achieve a sustained HCV clearance rate comparable with hepatitis C alone. In dually infected patients, the treatment may alter the dominant, ruling hepatitis virus.

SWI/SNF chromatin remodelling complex and retroviral gene silencing

Because of the unique infectious cycle of retroviruses which involves the integration of the retroviral genome into the host chromosome, many cellular chromosomal proteins are used by the virus to maintain its gene expression. At the same time, cellular mechanisms for the surveillance and exclusion of non-self expression by such intragenomic parasites operate as an important host defence system in the cellular nuclei. Retroviruses have strategies for escaping from host defence systems, such as by maintaining or reactivating viral expression in specific host cell types. Understanding such epigenetical regulation would be essential for progress in retroviral virology. In this review, we emphasise the importance of the chromatin remodelling factor SWI/SNF complex as one of the key players in epigenetic regulation of host and viral gene expression. An understanding of these mechanisms will surely lead to new ideas on the pathogenicity of this virus, on the latent infection observed in many other viruses, and further forward the design of unique retroviral vectors for long-term transgene expression, providing strong tools for human gene therapy and regenerative medicine.

Characterization of CD8(+) effector T cell responses in volunteers immunized with Salmonella enterica serovar Typhi strain Ty21a typhoid vaccine

Salmonella enterica serovar Typhi (S. typhi) strain Ty21a remains the only licensed attenuated typhoid vaccine. Despite years of research, the identity of the protective immunological mechanisms elicited by immunization with the Ty21a typhoid vaccine remains elusive. The present study was designed to characterize effector T cell responses in volunteers immunized with S. typhi strain Ty21a typhoid vaccine. We determined whether immunization with Ty21a induced specific CTL able to lyse S. typhi-infected cells and secrete IFN-gamma, a key effector molecule against intracellular pathogens. We measured the functional activity of these CTL by a (51)Cr-release assay using 8-day restimulated PBMC from Ty21a vaccinees as effector cells and S. Typhi-infected autologous PHA-activated PBMC as target cells. Most vaccinees exhibited consistently increased CD8-mediated lysis of targets by postimmunization PBMC when compared with preimmunization levels. We also developed an IFN-gamma ELISPOT assay to quantify the frequency of IFN-gamma spot-forming cells (SFC) in PBMC from Ty21a vaccinees using an ex vivo system. Significant increases in the frequency of IFN-gamma SFC following immunization (mean +/- SD, 393 +/- 172; range 185-548 SFC/10(6) PBMC; p = 0.010), as compared with preimmunization levels, were observed. IFN-gamma was secreted predominantly by CD8(+) T cells. A strong correlation was recorded between the cytolytic activity of CTL lines and the frequency of IFN-gamma SFC (r(2) = 0.910, p < 0.001). In conclusion, this work constitutes the first evidence that immunization of volunteers with Ty21a elicits specific CD8(+) CTL and provides an estimate of the frequency of CD8(+) IFN-gamma-secreting cells induced by vaccination.