Improved dendritic cell-based immunization against hepatitis C virus using peptide inhibitors of interleukin 10

A new standardization for the use of chicken embryo: selection of target from the phage display library and infection

The filamentous bacteriophage M13KO7 (M13) is the most used in phage display (PD) technology and, like other phages, has been applied in several areas of medicine, agriculture, and in the food industry. One of the advantages is that they can modulate the immune response in the presence of pathogenic microorganisms, such as bacteria and viruses. This study evaluated the use of phage M13 in the chicken embryos model. We inoculated 13-day-old chicken embryos with Salmonella Pullorum (SP) and then evaluated survival for the presence of phage M13 or E. coli ER2738 (ECR) infected with M13. We found that the ECR bacterium inhibits SP multiplication in 0.32 (M13-infected ECR) or 0.44 log UFC/mL (M13-uninfected ECR) and that the ECR-free phage M13 from the PD library can be used in chicken embryo models. This work provides the use of the chicken embryo as a model to study systemic infection and can be employed as an analysis tool for various peptides that M13 can express from PD selection. KEY POINTS: • SP-infected chicken embryo can be a helpful model of systemic infection for different tests. • Phage M13 does not lead to embryonic mortality or cause serious injury to embryos. • Phage M13 from the PD library can be used in chicken embryo model tests.

Umifenovir Epigenetically Targets the IL-10 Pathway in Therapy against Coxsackievirus B4 Infection

Umifenovir, a broad-spectrum nonnucleoside antiviral drug, has a promising efficacy against coxsackievirus B4 (CVB4) infection, but its mechanism remains unclear. CVB4 is a common human single-stranded RNA virus that belongs to the Picornaviridae family and the Enterovirus genus. Enterovirus can cause severe diseases, such as meningitis, myocarditis, pancreatitis, insulin-dependent diabetes, and several other diseases, in both adults and children. We have previously demonstrated the critical role of interleukin 10 (IL-10) in promoting CVB4 infection and the downregulation of IL-10 by umifenovir. To further explore the underlying mechanisms of umifenovir, we characterized the epigenetic regulation of IL-10 in IL-10 knockout RAW264.7 cells and a BALB/c mouse splenocyte model. Mechanistically, we found that umifenovir inhibited CVB4-activated IL-10 by enhancing the methylation level of the repressive histones H3K9me3 and H3K27me3 while reducing the acetylation level of the activating histone H3K9ac in the promoter region of the IL-10 gene. Furthermore, using a chromosome conformation capture approach, we discovered that CVB4 infection activated the IL-10 gene by forming an intrachromosomal interaction between the IL-10 gene promoter and an intronic enhancer of the downstream MK2 (mitogen-activated protein kinase [MAPK]-activated protein kinase 2 [MAPKAPK2]) gene, a critical component of the p38-MAPK signaling pathway, which is required for IL-10 gene expression. However, umifenovir treatment abolished this spatial conformation and chromatin interaction, thus reducing the continuous expression of IL-10 and subsequent CVB4 replication. In conclusion, this study reveals a novel epigenetic mechanism by which umifenovir controls CVB4 infections, thus laying a theoretical foundation for therapeutic use of umifenovir. IMPORTANCE Viral infections are major threats to human health because of their strong association with a variety of inflammation-related diseases, especially cancer. Many antiviral drugs are performing poorly in treating viral infections. This is probably due to the immunosuppressive effect of highly expressed IL-10, which is caused by viral infection. Umifenovir is a broad-spectrum antiviral drug. Our recent studies showed that umifenovir has a significant inhibitory effect on CVB4 infection and can reduce IL-10 expression caused by CVB4. However, another antiviral drug, rupintrivir, showed good antiviral activity but had no effect on the expression of IL-10. This suggests that the regulation of IL-10 expression is a key part of the antiviral mechanism of umifenovir. Therefore, due to the dual function of the inhibition of CVB4 replication and the regulation of immune antiviral pathway, the mechanism of umifenovir is of great value to study.

Alternative use of phage display: phage M13 can remain viable in the intestines of poultry without causing damage

Phage display (PD) is a tool for developing new molecules to control pathogens. Peptides selected by PD are commonly synthesised and tested, but the use of phage M13 displaying the selected peptides as a direct biding in the intestinal tract has not yet been tested. This study evaluated whether phage M13 can remain viable in the chicken gastrointestinal tract and whether it causes injury or humoral immune response. We inoculated phage M13 or E. coli ER2738 (ECR) infected with M13 into birds at different ages. We found the virus in faeces at 5 or 13 days after inoculation, just when it infected the ECR. The presence of phage M13 or ECR did not result in gut injuries and had no impacts on weight gain and bird health. Furthermore, the levels of IgY were similar in all treatments, which indicates that the virus can be used in chicken until 42 days without being recognised by the immune system. This work provides a scientific basis for the use of PD as a tool in numerous applications to control different pathogens.

Phage M13 remains viable in the bird's intestine if inoculated with E. coli ER2738.

Bacteriophage M13 does not damage the chicken gut.

Phage M13 remains in the gut without leading to a humoral response up to 42 days.

The Potential Advantage of Targeting Both PD-L1/PD-L2/PD-1 and IL-10-IL-10R Pathways in Acute Myeloid Leukemia

Tumor cells promote the suppression of host anti-tumor type 1 T cell responses by various mechanisms, including the upregulation of surface inhibitory molecules such as programmed death ligand (PD-L)-1, and the production of immunosuppressive cytokines such as interleukin-10 (IL-10). There are over 2000 trials investigating PD-L1 and/or its receptor programmed-death 1 (PD-1) blockade in cancer, leading to the approval of PD-1 or PD-L1 inhibitors in several types of solid cancers and in hematological malignancies. The available data suggest that the molecule PD-L1 on antigen-presenting cells suppresses type 1 T cell immune responses such as cytotoxicity, and that the cytokine IL-10, in addition to downregulating immune responses, increases the expression of inhibitory molecule PD-L1. We hypothesize that the manipulation of both the co-inhibitory network (with anti-PD-L1 blocking antibodies) and suppressor network (with anti-IL-10 blocking antibodies) is an attractive immunotherapeutic intervention for acute myeloid leukemia (AML) patients ineligible for standard treatment with chemotherapy and hematopoietic stem cell transplantation, and with less severe adverse reactions. The proposed combination of these two immunotherapies represents a new approach that can be readily translated into the clinic to improve the therapeutic efficacy of AML disease treatment.

Blocking IL-10 signaling with soluble IL-10 receptor restores in vitro specific lymphoproliferative response in dogs with leishmaniasis caused by Leishmania infantum

rIL-10 plays a major role in restricting exaggerated inflammatory and immune responses, thus preventing tissue damage. However, the restriction of inflammatory and immune responses by IL-10 can also favor the development and/or persistence of chronic infections or neoplasms. Dogs that succumb to canine leishmaniasis (CanL) caused by L. infantum develop exhaustion of T lymphocytes and are unable to mount appropriate cellular immune responses to control the infection. These animals fail to mount specific lymphoproliferative responses and produce interferon gamma and TNF-alpha that would activate macrophages and promote destruction of intracellular parasites. Blocking IL-10 signaling may contribute to the treatment of CanL. In order to obtain a tool for this blockage, the present work endeavored to identify the canine casIL-10R1 amino acid sequence, generate a recombinant baculovirus chromosome encoding this molecule, which was expressed in insect cells and subsequently purified to obtain rcasIL-10R1. In addition, rcasIL-10R1 was able to bind to homologous IL-10 and block IL-10 signaling pathway, as well as to promote lymphoproliferation in dogs with leishmaniasis caused by L. infantum.

Intratumoral Delivery of Immunotherapy-Act Locally, Think Globally

Immune mechanisms have evolved to cope with local entry of microbes acting in a confined fashion but eventually inducing systemic immune memory. Indeed, in situ delivery of a number of agents into tumors can mimic in the malignant tissue the phenomena that control intracellular infection leading to the killing of infected cells. Vascular endothelium activation and lymphocyte attraction, together with dendritic cell-mediated cross-priming, are the key elements. Intratumoral therapy with pathogen-associated molecular patterns or recombinant viruses is being tested in the clinic. Cell therapies can be also delivered intratumorally, including infusion of autologous dendritic cells and even tumor-reactive T lymphocytes. Intralesional virotherapy with an HSV vector expressing GM-CSF has been recently approved by the Food and Drug Administration for the treatment of unresectable melanoma. Immunomodulatory monoclonal Abs have also been successfully applied intratumorally in animal models. Local delivery means less systemic toxicity while focusing the immune response on the malignancy and the affected draining lymph nodes.

Investigation the Possibility of Using Peptides with a Helical Repeating Pattern of Hydro-Phobic and Hydrophilic Residues to Inhibit IL-10

Blockade of IL-10 signalling clears chronic viral and bacterial infections. Immunization together with blockade of IL-10 signalling or relatively low level of IL-10 further enhances viral and bacterial clearance. IL-10 functions through binding to interleukin 10 receptor (IL-10R). Here we showed that peptides P1 and P2 with the hydrophobic and hydrophilic pattern of the IL10R-binding helix in IL-10 could bind with either IL-10R1 or IL-10, and inhibit inflammatory signals with long duration and negligible cytotoxicity in vitro. Furthermore, P2 can enhance antigen specific CD8+ T cell responses in mice induced by the vaccine based on a long peptide of protein E7 in a human papillomavirus type 16.

Clinical testing of a dendritic cell targeted therapeutic vaccine in patients with chronic hepatitis C virus infection

The lack of antiviral cellular immune responses in patients with chronic hepatitis C virus (HCV) infection suggests that T-cell vaccines may provide therapeutic benefit. Due to the central role that dendritic cells (DC) play in the activation of T-cell responses, our aim was to carry out a therapeutic vaccination clinical trial in HCV patients using DC. Five patients with chronic HCV infection were vaccinated with three doses of 5 × 10⁶ or 10⁷ autologous DC transduced with a recombinant adenovirus encoding NS3 using the adapter protein CFh40L, which facilitates DC transduction and maturation. No significant adverse effects were recorded after vaccination. Treatment caused no changes in serum liver enzymes nor in viral load. Vaccination induced weak but consistent expansion of T-cell responses against NS3 and adenoviral antigens. Patients’ DC, as opposed to murine DC or DC from healthy subjects, secreted high IL-10 levels after transduction, inducing the activation of IL-10–producing T cells. IL-10 blockade during vaccine preparation restored its ability to stimulate anti-NS3 Th1 responses. Thus, vaccination with adenovirus-transduced DC is safe and induces weak antiviral immune responses. IL-10 associated with vaccine preparation may be partly responsible for these effects, suggesting that future vaccines should consider concomitant inhibition of this cytokine.

Relationships between interleukin-12B and interleukin-10 gene polymorphisms and hepatitis C in Chinese Han hemodialysis patients

BACKGROUND AND AIMS

Hepatitis C virus (HCV) commonly causes a chronic infection but portion of hemodialysis patients are able to resistant to HCV infection, even clear the virus naturally. Interleukin-10 (IL-10) and interleukin-12 (IL-12) are crucial regulators of the immune response to T-helper 1 (Th1) or T-helper 2 (Th2) categories and play a role in autoimmune and infectious diseases. This study was undertaken to investigate the possible association of genetic polymorphisms of 3' untranslated region (3'UTR) of the IL-12B (-1188) and IL-10 (-592 and -819) and hepatitis C in Chinese Han hemodialysis (HD) patients.

METHODS

The genotyping of IL-12B 3'UTR and IL-10 -592 and -819 were performed by polymerase chain reaction (PCR) restriction fragment length polymorphism (RFLP) method.

RESULTS

Compared with the IL-12B-AA genotype, CC and combined CC/AC genotypes were associated with a significant decreased risk of HCV infection in Chinese hemodialysis patients (p < 0.001). However, the IL-10-592 and -819 genotypes were not found significant difference both between the anti-HCV (+) and anti-HCV (-) patients (p > 0.05) and the persistent infection and viral clearance HD patients (p > 0.05).

CONCLUSIONS

The present study indicated that the polymorphisms of IL-12B 3'UTR might contribute to the susceptibility of HCV infection in Chinese HD population.

Manipulating IL-10 signalling blockade for better immunotherapy

Interleukin 10 is a cytokine with the ability to reduce or terminate inflammation. Chronic viral infection, such as infection of chronic hepatitis B, hepatitis C and HIV, has increased levels of interleukin 10 in peripheral blood. Serum IL-10 levels are also high in certain cancers. Blocking IL-10 signalling at the time of immunisation clears chronic viral infection and prevents tumour growth in animal models. We review recent advances in this area, with the emphasis on potential use of this novel strategy to treat chronic viral infection and cancer in human.

An insight into the diagnosis and pathogenesis of hepatitis C virus infection

This review focuses on research findings in the area of diagnosis and pathogenesis of hepatitis C virus (HCV) infection over the last few decades. The information based on published literature provides an update on these two aspects of HCV. HCV infection, previously called blood transmitted non-A, non-B infection, is prevalent globally and poses a serious public health problem worldwide. The diagnosis of HCV infection has evolved from serodetection of non-specific and low avidity anti-HCV antibodies to detection of viral nucleic acid in serum using the polymerase chain reaction (PCR) technique. Current PCR assays detect viral nucleic acid with high accuracy and the exact copy number of viral particles. Moreover, multiplex assays using real-time PCR are available for identification of HCV-genotypes and their isotypes. In contrast to previous methods, the newly developed assays are not only fast and economic, but also resolve the problem of the window period as well as differentiate present from past infection. HCV is a non-cytopathic virus, thus, its pathogenesis is regulated by host immunity and metabolic changes including oxidative stress, insulin resistance and hepatic steatosis. Both innate and adaptive immunity play an important role in HCV pathogenesis. Cytotoxic lymphocytes demonstrate crucial activity during viral eradication or viral persistence and are influenced by viral proteins, HCV-quasispecies and several metabolic factors regulating liver metabolism. HCV pathogenesis is a very complex phenomenon and requires further study to determine the other factors involved.

Dendritic cell co-stimulatory and co-inhibitory markers in chronic HCV: an Egyptian study

AIM

To assess co-stimulatory and co-inhibitory markers of dendritic cells (DCs) in hepatitis C virus (HCV) infected subjects with and without uremia.

METHODS

Three subject groups were included in the study: group 1 involved 50 control subjects, group 2 involved 50 patients with chronic HCV infection and group 3 involved 50 HCV uremic subjects undergoing hemodialysis. CD83, CD86 and CD40 as co-stimulatory markers and PD-L1 as a co-inhibitory marker were assessed in peripheral blood mononuclear cells by real-time polymerase chain reaction. Interleukin-10 (IL-10) and hyaluronic acid (HA) levels were also assessed. All findings were correlated with disease activity, viral load and fibrogenesis.

RESULTS

There was a significant decrease in co-stimulatory markers; CD83, CD86 and CD40 in groups 2 and 3 vs the control group. Co-stimulatory markers were significantly higher in group 3 vs group 2. There was a significant elevation in PD-L1 in both HCV groups vs the control group. PD-L1 was significantly lower in group 3 vs group 2. There was a significant elevation in IL-10 and HA levels in groups 2 and 3, where IL-10 was higher in group 3 and HA was lower in group 3 vs group 2. HA level was significantly correlated with disease activity and fibrosis grade in group 2. IL-10 was significantly correlated with fibrosis grade in group 2. There were significant negative correlations between co-stimulatory markers and viral load in groups 2 and 3, except CD83 in dialysis patients. There was a significant positive correlation between PD-L1 and viral load in both HCV groups.

CONCLUSION

A significant decrease in DC co-stimulatory markers and a significant increase in a DC co-inhibitory marker were observed in HCV subjects and to a lesser extent in dialysis patients.

Importance of IL-10 and IL-6 during chronic hepatitis C genotype-1 treatment and their relation with IL28B

This paper investigates serum levels of interleukin 10 (IL-10) and interleukin 6 (IL-6) in patients with chronic hepatitis C genotype 1 (CHC-GT1), the relation of each with clinical and virological characteristics, how they affect the response to combined therapy and their relation with the IL28B polymorphisms rs12979860. Serum level expression and the polymorphism of IL-10, IL-6 and IL28B were determined in 138 CHC-GT1 patients, treated with pegylated interferon/ribavirin (pegIFN-α/RBV) for 48 weeks, in the following samples: baseline, week-12 (during treatment) and week-72 (post-treatment). 77 patients (56%) presented Sustained Virological Response (SVR) and 61 (44%) were non-SVR. Multivariate logistic regression showed that age ≤ 40 years (aOR=3.7, 95%CI=1.5-8.9, P=0.004), low activity of gamma glutamyl transferase (GGT) (aOR=0.9, 95%CI=0.98-0.99, P=0.028), CC genotype of IL28B polymorphism (aOR=2.7, 95%CI=1.0-7.2, P=0.044) and low IL-6 (aOR=0.5, 95%CI=0.3-1.0, P=0.038) were predictor factors of virological response. In all patients, following treatment, IL-6 decreased at week-12 (P=0.004) from baseline and had returned to basal values at week-72. Serum IL-10 concentration was significantly decreased at week-72 only in SVR patients (P ≤ 0.001). When patients were stratified by IL28B polymorphisms rs12979860 CC vs non-CC patients, a statistically significant decrease in IL-10 at week-72 in both groups was observed (P=0.003 and P ≤ 0.001, respectively). None of the polymorphisms of IL-10 or IL-6 studied were associated with SVR.

CONCLUSIONS

CC genotype of IL28B and low IL-6 serum concentration are factors associated independently with SVR. Moreover, decreased IL-10 at week-72 is associated with SVR in both CC and non-CC patients, and both factors are important to determine the effectiveness of treatment.

Dendritic cell-based immunity and vaccination against hepatitis C virus infection

Hepatitis C virus (HCV) has chronically infected an estimated 170 million people worldwide. There are many impediments to the development of an effective vaccine for HCV infection. Dendritic cells (DC) remain the most important antigen-presenting cells for host immune responses, and are capable of either inducing productive immunity or maintaining the state of tolerance to self and non-self antigens. Researchers have recently explored the mechanisms by which DC function is regulated during HCV infection, leading to impaired antiviral T-cell responses and so to persistent viral infection. Recently, DC-based vaccines against HCV have been developed. This review summarizes the current understanding of DC function during HCV infection and explores the prospects of DC-based HCV vaccine. In particular, it describes the biology of DC, the phenotype of DC in HCV-infected patients, the effect of HCV on DC development and function, the studies on new DC-based vaccines against HCV infection, and strategies to improve the efficacy of DC-based vaccines.

Restoration of innate and adaptive immune responses by HCV viral inhibition with an induction approach using natural interferon-beta in chronic hepatitis C

Chronic hepatitis C (CHC) is a serious medical problem necessitating more effective treatment. This study investigated the hypothesis that an induction approach with nIFN-beta for 24 weeks followed by PEG-IFN-alpha+ribavirin (standard of care: SOC) for 48 weeks (novel combination treatment: NCT) would increase the initial virologic response rate and restore innate and adaptive immune responses in CHC. Seven CHC patients with a high viral load and genotype 1b were treated with NCT. Serum cytokine and chemokine levels were evaluated during NCT. NCT prevented viral escape and breakthrough resulting in persistent viral clearance of HCVRNA. IL-15 was increased at the end of induction therapy in both early virologic responders (EAVRs) and late virologic responders (LAVRs); CXCL-8, CXCL-10, and CCL-4 levels were significantly decreased (P < 0.05) in EAVR but not in LAVR during NCT, and IL-12 increased significantly (P < 0.05) and CXCL-8 decreased significantly (P < 0.05) after the end of NCT in EAVR but not in LAVR. NCT prevented viral breakthrough with viral clearance leading to improvement of innate and adaptive immunity resulting in a sustained virologic response (SVR). NCT (n = 8) achieved a higher SVR rate than SOC (n = 8) in difficult-to-treat CHC patients with genotype 1 and high viral loads.

Therapeutic vaccination against chronic hepatitis C virus infection

Approximately 170 million people worldwide are chronic carriers of Hepatitis C virus (HCV). To date, there is no prophylactic vaccine available against HCV. The standard-of-care therapy for HCV infection involves a combination of pegylated interferon-α and ribavirin. This therapy, which is commonly associated with side effects, has a curative rate varying from 43% (HCV genotype 1) to 80% (HCV genotype 2). In 2011, two direct-acting antiviral agents, telaprevir and boceprevir, were approved by the US Food and drug Administration and are now being used in combination with standard-of-care therapy in selected patients infected with HCV genotype 1. Although both drugs are promising, resulting in a shortening of therapy, these drugs also induce additional side effects and have reduced efficacy in patients who did not respond to standard-of-care previously. An alternative approach would be to treat HCV by stimulating the immune system with a therapeutic vaccine ideally aimed at (i) the eradication of HCV-infected cells and (ii) neutralization of infectious HCV particles. The challenge is to develop therapeutic vaccination strategies that are either at least as effective as antiviral drugs but with lower side effects, or vaccines that, when combined with antiviral drugs, can circumvent long-term use of these drugs thereby reducing their side effects. In this review, we summarize and discuss recent preclinical developments in the area of therapeutic vaccination against chronic HCV infection. Although neutralizing antibodies have been described to exert protective immunity, clinical studies on the induction of neutralizing antibodies in therapeutic settings are limited. Therefore, we will primarily discuss therapeutic vaccines which aim to induce effective cellular immune response against HCV.

T cell immunopathogenesis and immunotherapeutic strategies for chronic hepatitis B virus infection

Hepatitis B is caused by the host immune response and T cells play a major role in the immunopathogenesis. More importantly, T cells not only destroy hepatocytes infected by hepatitis B virus (HBV), but also control HBV replication or eradicate HBV in a noncytolytic manner. Therefore, analysis of T cell immune response during acute and chronic HBV infection is important to develop a strategy for successful viral control, which could lead to immunotherapy for terminating persistent HBV infection. There have been many attempts at immunotherapy for chronic HBV infection, and some have shown promising results. High viral load has been shown to suppress antiviral immune responses and immunoinhibitory signals have been recently elucidated, therefore, viral suppression by nucleos(t)ide analogs, stimulation of antiviral immune response, and suppression of the immunoinhibitory signals must be combined to achieve desirable antiviral effects.

Isolation and optimization of murine IL-10 receptor blocking oligonucleotide aptamers using high-throughput sequencing

Interleukin-10 (IL-10) is a key suppressor of inflammation in chronic infections and in cancer. In mice, the inability of the immune system to clear viral infections or inhibit tumor growth can be reversed by antibody-mediated blockade of IL-10 action. We used a modified selection protocol to isolate RNA-based, nuclease-resistant, aptamers that bind to the murine IL-10 receptor. After 5 rounds of selection high-throughput sequencing (HTS) was used to analyze the library. Using distribution statistics on about 11 million sequences, aptamers were identified which bound to IL-10 receptor in solution with low K(d). After 12 rounds of selection the predominant IL-10 receptor-binding aptamer identified in the earlier rounds remained, whereas other high-affinity aptamers were not detected. Prevalence of certain nucleotide (nt) substitutions in the sequence of a high-affinity aptamer present in round 5 was used to deduce its secondary structure and guide the truncation of the aptamer resulting in a shortened 48-nt long aptamer with increased affinity. The aptamer also bound to IL-10 receptor on the cell surface and blocked IL-10 function in vitro. Systemic administration of the truncated aptamer was capable of inhibiting tumor growth in mice to an extent comparable to that of an anti- IL-10 receptor antibody.

Vaccination with dendritic cells pulsed with hepatitis C pseudo particles induces specific immune responses in mice

AIM

To explore dendritic cells (DCs) multiple functions in immune modulation.

METHODS

We used bone-marrow derived dendritic cells from BALB/c mice pulsed with pseudo particles from the hepatitis C virus to vaccinate naive BALB/c mice. Hepatitis C virus (HCV) pseudo particles consist of the genotype 1b derived envelope proteins E1 and E2, covering a non-HCV core structure. Thus, not a single epitope, but the whole "viral surface" induces immunogenicity. For vaccination, mature and activated DC were injected subcutaneously twice.

RESULTS

Humoral and cellular immune responses measured by enzyme-linked immunosorbent assay and interferon-gamma enzyme-linked immunosorbent spot test showed antibody production as well as T-cells directed against HCV. Furthermore, T-cell responses confirmed two highly immunogenic regions in E1 and E2 outside the hypervariable region 1.

CONCLUSION

Our results indicate dendritic cells as a promising vaccination model for HCV infection that should be evaluated further.

Phage display of combinatorial peptide libraries: application to antiviral research

Given the growing number of diseases caused by emerging or endemic viruses, original strategies are urgently required: (1) for the identification of new drugs active against new viruses and (2) to deal with viral mutants in which resistance to existing antiviral molecules has been selected. In this context, antiviral peptides constitute a promising area for disease prevention and treatment. The identification and development of these inhibitory peptides require the high-throughput screening of combinatorial libraries. Phage-display is a powerful technique for selecting unique molecules with selective affinity for a specific target from highly diverse combinatorial libraries. In the last 15 years, the use of this technique for antiviral purposes and for the isolation of candidate inhibitory peptides in drug discovery has been explored. We present here a review of the use of phage display in antiviral research and drug discovery, with a discussion of optimized strategies combining the strong screening potential of this technique with complementary rational approaches for identification of the best target. By combining such approaches, it should be possible to maximize the selection of molecules with strong antiviral potential.

Elevation of plasma soluble human leukocyte antigen-G in patients with chronic hepatitis C virus infection

The subversion of immune responses that hepatitis C virus (HCV) uses to escape immune surveillance and to establish persistent infection has been poorly understood. The immune-suppressive molecule human leukocyte antigen-G (HLA-G) has been supposed to play important roles in viral infection. In the current study, HCV genotype was analyzed in 67 chronic HCV-infected (CHC) patients. Plasma soluble sHLA-G (including sHLA-G1 and HLA-G5), interleukin-10 (IL-10), and interferon-γ (IFN-γ) levels were determined in these CHC patients and in healthy subjects by enzyme-linked immunosorbent assay, and the sHLA-G isoforms present in plasma were determined by Western blot. Data showed that HCV 1b was the predominant genotype, with a prevalence of 64.2%. sHLA-G was dramatically increased in CHC patients (median: 85.54 U/ml, range: 19.40-204.07) over that in normal controls (median: 9.13 U/ml, range: 5.07-69.56) (p < 0.001). Western blotting revealed that plasma sHLA-G was derived from sHLA-G1 and HLA-G5. IL-10 and IFN-γ levels were also significant higher in CHC patients than in normal controls (median: 16.3 pg/ml vs 1.8 pg/ml, p < 0.001, and 1025.3 pg/ml vs 858.3 pg/ml, p = 0.03, respectively). No significant association was observed for the HCV genotype and viral RNA load with the levels of sHLA-G, IL-10, and IFN-γ in CHC patients. These results indicate that elevation of sHLA-G expression in HCV patients was independent of viral genotype and viral RNA load. Given its immunotolerant property, an increase in sHLA-G may play a role in the persistency of HCV infection.