Neutralizing activities of caprine antibodies towards conserved regions of the HCV envelope glycoprotein E2

Exploring the Impact of Different Inflammatory Cytokines on Hepatitis C Virus Infection

Hepatitis C virus (HCV) infection is a global health concern affecting millions worldwide. Chronic HCV infection often leads to liver inflammation and can progress to cirrhosis and hepatocellular carcinoma. Inflammatory cytokines are crucial in modulating the immune response during HCV infection. This review aims to investigate the impact of different inflammatory cytokines on HCV infection and associated immune responses. This review was conducted to identify relevant studies on the interplay between inflammatory cytokines and HCV infection. The analysis focused on the effects of key inflammatory cytokines, including tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), interleukin-1 (IL-1), and interferon-gamma (IFN-γ), on HCV replication, immune cell activation, and liver inflammation. The findings reveal that these inflammatory cytokines can significantly influence HCV infection and the subsequent immune response. TNF-α, IL-6, and IL-1 have been shown to enhance HCV replication, while IFN-γ exerts antiviral effects by inhibiting viral replication and promoting immune cell-mediated clearance of infected hepatocytes. Moreover, these cytokines contribute to the recruitment and activation of immune cells, such as natural killer cells, T cells, and macrophages, which play critical roles in controlling HCV infection. Understanding the precise mechanisms by which inflammatory cytokines impact HCV infection is crucial for developing more targeted therapeutic strategies. Modulating the levels or activity of specific cytokines may provide opportunities to attenuate HCV replication, reduce liver inflammation, and improve treatment outcomes. In conclusion, this review highlights the significance of inflammatory cytokines in influencing HCV infection and associated immune responses.

Keyhole Limpet Hemocyanin-Conjugated Peptides from Hepatitis C Virus Glycoproteins Elicit Neutralizing Antibodies in BALB/c Mice

Currently, no vaccine to prevent hepatitis C virus (HCV) infection is available. A major challenge in developing an HCV vaccine is the high diversity of HCV sequences. The purpose of immunization with viral glycoproteins is to induce a potent and long-lasting cellular and humoral immune response. However, this strategy only achieves limited protection, and antigen selection plays a crucial role in vaccine design. In this study, we investigated the humoral immune responses induced by intraperitoneal injection of keyhole limpet hemocyanin conjugated with 4 highly conserved peptides, including amino acids [aa]317-325 from E1 and aa418-429, aa502-518, and aa685-693 from E2, or 3 peptides from hypervariable region 1 (HVR1) of E2, including the N terminus of HVR1 (N-HVR1, aa384-396), C terminus of HVR1 (C-HVR1, aa397-410), and HVR1 in BALB/c mice. The neutralizing activity against HCV genotypes 1-6 was assessed using the cell culture HCV (HCVcc) system. The results showed that the 4 conserved peptides efficiently induced antibodies with potent neutralizing activity against 3 or 4 genotypes. Antibodies induced by aa685-693 conferred potent protection (>50%) against genotypes 2, 4, and 5. Peptide N-HVR1 elicited antibodies with the most potent neutralization activities against 3 HCV genotypes: TNcc(1a), S52(3a), and ED43(4a). These findings suggested that peptides within HCV glycoproteins could serve as potent immunogens for vaccine design and development.

A multiepitope peptide vaccine against HCV stimulates neutralizing humoral and persistent cellular responses in mice

BACKGROUND

Although DAAs hold promise to significantly reduce rates of chronic HCV infections, its eradication still requires development of an effective vaccine. Prolonged T cell responses and cross neutralizing antibodies are ideal for vaccination against the infection. We aimed to design and synthesize a 6 multi epitope peptide vaccine candidate and provide evidence for production of extended cellular and neutralizing Abs in mice.

METHODS

Six peptides derived from conserved epitopes in E1, E2 (n = 2),NS4B, NS5A and NS5B were designed, synthesized in a multiple antigenic peptide (MAP) form and administered w/o adjuvant to BALB/c mice as HCVp6-MAP at doses ranging from 800 ng to 16 μg. Humoral responses to structural epitopes were assayed by ELISA at different times after injection. ELISpot assay was used to evaluate IFN ɣ producing CD4+/ CD8+ T- lymphocytes at extended durations i.e. > 20 weeks. Viral neutralization by mice sera was tested for genotypes 2a (JFH1) and a chimeric 2a/4a virus (ED43/JFH1) in HCVcc culture.

RESULTS

HCVp6-MAP confers potent viral neutralization and specific cellular responses at > 1600 ng/ animal for at least 20 weeks.

CONCLUSION

We report on a promising anti HCV vaccine for future studies on permissive hosts and in clinical trials.

Mice Antibody Response to Conserved Nonadjuvanted Multiple Antigenic Peptides Derived from E1/E2 Regions of Hepatitis C Virus

Synthetic peptides are one of the hepatitis C virus (HCV)-specific small molecules that have antiviral activity and represent a target for HCV vaccine. This study aims to determine the lowest concentration of adjuvanted and non-adjuvanted (multiple antigenic peptide [MAP]) form of three conserved HCV envelope peptides that can induce murine immunogenic responses and evaluate the neutralization capacities of the generated antibodies (Abs) against HCV in cultured Huh7.5 cells. In this study, three HCV synthetic peptides, E1 peptide (a.a 315-323) and E2 peptides (a.a 412-419 and a.a 516-531) were synthesized. Female Balb/c mice were immunized with different concentration of either adjuvanted linear peptides or nonadjuvanted MAP peptides to determine the lowest dose that generates Ab responses enough to confer viral neutralization in vitro. The humoral responses targeting these peptides in immunized mice sera were measured by enzyme-linked immunosorbent assay (ELISA). Viral neutralization capacities of the generated mice Abs were assessed using Huh7.5 cells infected with the HCVcc infectious system (J6/JFH-1). The results of this study showed that the MAPs induce higher Ab titers than adjuvanted linear peptides after 4 weeks of immunization (p = 0.003). The viral neutralization experiments showed that the immunized mice sera contain anti E1/E2 Abs that blocked HCVcc (J6/JFH-1) entry into Huh7.5 cells. In conclusion, the three HCV envelope MAP peptides are more immunogenic and produce higher neutralizing Abs than linear peptides; therefore, they can be essential components for HCV vaccine.

Antiviral activity of virocidal peptide derived from NS5A against two different HCV genotypes: an in vitro study

This study aimed at assessment of the antiviral activity of an amphipathic α-helical peptide derived from the hepatitis C virus NS5A known as C5A virocidal peptide against different HCV genotypes. Two sources of HCV virus for in vitro study: HCV genotype 4 sera samples and JFH-1 infectious culture system genotype 2a were used. Several virocidal peptide concentrations were tested to determine the concentration that inhibits HCV propagation in Huh 7.5 cells according to three different prortocols (pre-infection, coinfection, and post infection). The capacity of the virocidal peptide to block HCV in Huh7.5 cells infected with different 10 individual serum samples was evaluated. In the pre-infection protocol, virocidal concentration (20, 50, and 75 μM) showed no viral RNA. In the co-infection protocol, virocidal concentrations (10, 20, 50, 75 μM) showed no viral RNA while in post-infection protocol, 75 μM was the only concentration that blocked the HCV activity. Results of Huh7.5 cell line transfected with HCV cc J6/JFH and treated with virocidal peptide revealed that only the higher virocidal concentration (75 μM) showed no amplification. The percentage of virocidal blocking in the 10 HCV individual serum samples was 60%. In conclusion, the C5A virocidal peptide has potent antiviral activity against HCV.

Mouse monoclonal antibody towards e1 specific epitope blocks viral entry and intracellular viral replication in vitro

We characterized viral neutralization by a murine monoclonal antibody (mAb315) developed against conserved E1 specific epitope aa 315-323 at pre- and post-binding steps of infection into Huh7 cells. Detection of native virus in infected Huh7 cells by mAb315 were demonstrated by immunostaining. Inhibitions of viral entry by three different concentrations of mAb315 were measured by intracellular amplification of HCV RNA post infection. HCV RNA positive sera from 24 patients were used to infect Huh7 cell line in absence or presence of mouse monoclonal antibody produced in Balb/c mice or culture supernatant of mouse hybrid cells. Monoclonal Ab mAb315 could detect synthetic peptide p315 adsorbed on peripheral human lymphocytes by flow cytometry and showed high immuno reactivity to E1 viral antigen in infected Huh7 cells by immunostaining. Antibody-mediated neutralization assays demonstrated the ability of mAb315 to block HCV binding/entry to target cells at 0.73 mg/mL ascitic fluid or 250 µg/mL culture supernatant of mouse hybrid cells. Sixteen of 24 infected sera could infect Huh7 cells (67%). Binding/entry of HCV was completely blocked by mAb315 in 11/16 cases (69%). These findings suggest that mAb315 can induce HCV neutralization in vitro, which makes it a candidate for developing HCV therapeutic antibodies.

In vitro neutralization of HCV by goat antibodies against peptides encompassing regions downstream of HVR-1 of E2 glycoprotein

This article aims at testing several in vitro systems with various viral sources and cell lines for propagation of HCV to evaluate goat antibodies raised against three E2 epitopes in viral neutralization experiments. Four human cell lines (Huh-7, Huh-7.5, HepG2, and CaCo2) were tested using two different HCV viral sources; Genotype 4 infected sera and J6/JFH HCV cc particles. Neutralization capacity of goat Abs against conserved E2 epitopes; p412 (a.a 412-419), p517 (a.a 517-531), and p430 (a.a 430-447) were examined in the above mentioned in vitro systems. Although infection with patients' sera seems to mimic the in vitro situation, it has limited replication rates as compared with HCV cc particularly in Huh7.5 cells. Non-HCV adapted Huh-7 cells were also found susceptible for transfection with J6/JFH virus but at much slower kinetics. The results of the neutralization assay showed that anti p412 and anti p517 were highly neutralizing to HCVcc. Our data demonstrate that antibodies directed against the viral surface glycoprotein E2 reduced the infectivity of the J6/JFH virus and are promising agents for immunotherapy and HCV vaccine development.

WITHDRAWN: Immunogenicity and safety of HCV E1E2 peptide vaccine in chronically HCV-infected patients who did not respond to interferon based therapy

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Multiantibody strategies for HIV

Vaccination strategies depend entirely on the appropriate responsiveness of our immune system against particular antigens. For this active immunization to be truly effective, neutralizing antibodies (nAbs) need to efficiently counter the infectivity or propagation of the pathogen. Some viruses, including HIV, are able to take advantage of this immune response in order to evade nAbs. This review focuses on viral immune evasion strategies that result directly from a robust immune response to infection or vaccination. A rationale for multi-Ab therapy to circumvent this phenomenon is discussed. Progress in the formulation, production, and regulatory approval of monoclonal antibodies (mAbs) is presented.

Selection of epitope-based vaccine targets of HCV genotype 1 of Asian origin: a systematic in silico approach

Hepatitis C is the major health problem over the globe affecting approximately 200 million people worldwide and about 10 million Pakistani populations. Developing countries are especially facing the problems of HCV infection. Hence the goal of the study was to find out the antigenic epitopes that could be effective vaccine targets of HCV genotype 1 of Asian origin against HLA alleles frequently distributed in Asian countries. A total of 85 complete genome sequences of HCV 1 of Asian origin were retrieved from the HCV sequence database. Using in silico tools, T cell epitopes were predicted from conserved regions of all the available HCV 1 subtypes against Asian HLA alleles. Using 10 MHC I supertypes 51 epitopes was predicted as promiscuous binders. MHC class I supertypes A2 and B7 were found to be good promiscuous binders for a large number of predicted epitopes. Other alleles of MHC I supertypes (B57, B27, BX, B44) either were not respondent as promiscuous binders or responded only to a limited number of epitopes. Against 8 predominantly found Asian alleles of DRB1 supertype, 42 epitopes was predicted as promiscuous binders. MHC class II alleles DRB1-0101, DRB1-0701 and DRB1-1501 were the highest binders to promiscuous predicted epitopes while DRB1-0301 was the least binder for the predicted promiscuous epitopes of HCV 1 genotype of Asian origin. Literature review survey of predicted epitopes via IEDB also confirmed that great numbers of predicted epitopes are true positive. Hence, sophisticated selection of viral proteins and MHCs provided conserved promiscuous epitopes that can be used as effective vaccine candidates for all Asian counties.

ABBREVIATIONS

HCV - hepatitis C virus, MHC - major histocompatability complex, HLA - human leukocyte antigen, CTL - cytotoxic T lymphocytes.

Neutralization interfering antibodies: a "novel" example of humoral immune dysfunction facilitating viral escape?

The immune response against some viral pathogens, in particular those causing chronic infections, is often ineffective notwithstanding a robust humoral neutralizing response. Several evasion mechanisms capable of subverting the activity of neutralizing antibodies (nAbs) have been described. Among them, the elicitation of non-neutralizing and interfering Abs has been hypothesized. Recently, this evasion mechanism has acquired an increasing interest given its possible impact on novel nAb-based antiviral therapeutic and prophylactic approaches. In this review, we illustrate the mechanisms of Ab-mediated interference and the viral pathogens described in literature as able to adopt this "novel" evasion strategy.

Anti-hepatitis C virus E2 (HCV/E2) glycoprotein monoclonal antibodies and neutralization interference

The suggested HCV escape mechanism consisting in the elicitation of antibody (Ab) subpopulations interfering with the neutralizing activity of other Abs has recently been questioned. In particular, it was originally reported that Abs directed against the 436-447 region (epitope II) of HCV/E2 glycoprotein may interfere with the neutralizing Abs directed against the 412-423 region (epitope I) involved in the binding to CD81. In this paper, we investigate on the molecular features of this phenomenon describing an anti-HCV/E2 monoclonal Ab (mAb) (e509) endowed with a weak neutralizing activity, and whose epitope is centered on epitope II. Interestingly, e509 influenced the potent neutralizing activity of AP33, one of the best characterized anti-HCV/E2 mAb, whereas it did not show any interfering activity against two other broadly neutralizing mAbs (e20 and e137), whose epitopes partially overlap with that of e509 and which possibly displace it from the antigen. These data may give a possible clue to interpret the conflicting studies published to date on the mechanism of interference, suggesting the existence of at least two groups of broadly neutralizing anti-HCV/E2 Abs: (i) those whose epitope is focused on the 412-423 CD81-binding region and whose activity may be hampered by other Abs directed against the 436-447 region, and (ii) those directed against CD81-binding regions but whose epitope contains also residues within the 436-447 region recognized by interfering mAbs, thus competing with them for binding. The conflicting results of previous studies may therefore depend on the relative amount of each of these two populations in the polyclonal preparations used. Overall, a better comprehension of this phenomenon may be of importance in the set up of novel mAb-based anti-HCV therapeutic strategies.