Expression of core antigen of HCV genotype 3a and its evaluation as screening agent for HCV infection in Pakistan

The Study of Performance of a Nanoribbon Biosensor, Sensitized with Aptamers and Antibodies, upon Detection of Core Antigen of Hepatitis C Virus

The development of highly sensitive diagnostic systems for the early revelation of diseases in humans is one of the most important tasks of modern biomedical research, and the detection of the core antigen of the hepatitis C virus (HCVcoreAg)-a protein marker of the hepatitis C virus-is just the case. Our study is aimed at testing the performance of the nanoribbon biosensor in the case of the use of two different types of molecular probes: the antibodies and the aptamers against HCVcoreAg. The nanoribbon sensor chips employed are based on "silicon-on-insulator structures" (SOI-NR). Two different HCVcoreAg preparations are tested: recombinant β-galactosidase-conjugated HCVcoreAg ("Virogen", Watertown, MA, USA) and recombinant HCVcoreAg ("Vector-Best", Novosibirsk, Russia). Upon the detection of either type of antigen preparation, the lowest concentration of the antigen detectable in buffer with pH 5.1 was found to be approximately equal, amounting to ~10-15 M. This value was similar upon the use of either type of molecular probes.

Expression of HCV genotype-4 core antigen in prokaryotic E. coli system for diagnosis of HCV infection in Egypt

BACKGROUND

Egypt has a high prevalence of hepatitis C virus (HCV) infection with 92.5% of genotype-4.

AIM

This study aimed to clone and express the core gene of HCV genotype-4 for using it to develop a highly sensitive, specific, and cost-effective diagnostic assay for detecting HCV infection.

METHODS

Using synthetic HCV genotype-4 core gene, pET15b as E. coli expression vector, and 1 mM lactose as inducer, the HCV core protein (MW 17 kDa) was expressed in the form of inclusion bodies (IBs) that was purified and solubilized using 8 M guanidinium HCl. The recombinant core protein was in vitro refolded by a rapid dilution method for further purification using weak cation exchange liquid chromatography. The immunogenicity of the purified protein was tested by ELISA using 129 serum samples.

RESULTS

The recombinant core protein was successfully expressed and purified. The results also showed that the in-house anti-HCV core assay is accurate, specific (_~96.6%), and highly sensitive (_~100%) in accordance with the commercial ELISA kit.

CONCLUSION

The sensitivity, specificity, and reproducibility of the developed assay were high and promising to be used as a screening assay for detecting HCV infection.

Phylogenetic Characterization of the 5' Untranslated Region of Untypable HCV Genotypes Circulating in Pakistan

INTRODUCTION

Commercial methods for HCV genotyping is challenged by the increased prevalence of untypable genotypes in Pakistan.

OBJECTIVE

The aim of the current study was to perform nucleotide sequencing of 5' UTR region for genotyping of viral isolates circulating in Peshawar, Pakistan.

METHODS

The total number of commercially untypable samples were 94 in which 18 samples were sequenced for the characterization of 5' UTR region. Post-sequencing analysis was performed for genotype identification (n = 18) and molecular phylogenetic analysis.

RESULTS

The current study reveals different genotypes, that is, 10/18 viral isolates were found to be genotype 3a (55.55%), 3 isolates (genotype 3b, 16.66%), 2 isolates (genotype 6h/6g, 11.11%), 2 (6g/d, 11.11%), and 1 sample (genotype 1c, 5.55%). In addition, genotype 3a is the dominant representative of HCV circulating in Pakistan and has been increasing across the country.

CONCLUSION

The current study also reveals that genotype 6 (2 were genotype 6h/6g and 2 were 6g/d) is also circulating in Pakistan and not restricted to South China and Hong Kong.

HCV core antigen is a useful predictor during pegylated-interferon/ribavirin therapy in patients with hepatitis C virus genotype 1b

Enzyme immunoassays for quantifying hepatitis C virus (HCV) core antigen (Ag) have been proposed as an alternative to HCV RNA detection. The present study aimed to investigate the early kinetics of serum HCVcAg and its usefulness in predicting virological responses.The clinical data of 135 patients with chronic hepatitis C treated with pegylated interferon alpha (PEG-IFN-α) and ribavirin was retrospectively collected. The patients were grouped according to their treatment outcomes as follows: sustained virological response (SVR), nonsustained virological response (N-SVR), and relapse.Higher HCVcAg and HCV RNA levels were observed in patients in the N-SVR group than in the other groups at baseline. HCVcAg better predicted rapid virological response (RVR) compared with HCV RNA and had a predictive value similar to that of HCV RNA for SVR and early virological response. In the relapse group, HCV RNA decreased to 0 after 48 weeks, whereas HCVcAg was still detectable, indicating that HCVcAg more sensitively predicted relapse in antiviral therapy than HCV RNA.For patients treated with PEG-INF-α and ribavirin, HCVcAg may more sensitively predict relapse than HCV RNA.

The epidemiology of hepatitis C virus in Pakistan: systematic review and meta-analyses

To characterize hepatitis C virus (HCV) epidemiology in Pakistan and estimate the pooled mean HCV antibody prevalence in different risk populations, we systematically reviewed all available records of HCV incidence and/or prevalence from 1989 to 2016, as informed by the Cochrane Collaboration Handbook. This systematic review was reported following the PRISMA guidelines. Populations were classified into six categories based on the risk of exposure to HCV infection. Meta-analyses were performed using DerSimonian and Laird random-effects models with inverse variance weighting. The search identified one HCV incidence study and 341 prevalence measures/strata. Meta-analyses estimated the pooled mean HCV prevalence at 6.2% among the general population, 34.5% among high-risk clinical populations, 12.8% among populations at intermediate risk, 16.9% among special clinical populations, 55.9% among populations with liver-related conditions and 53.6% among people who inject drugs. Most reported risk factors in analytical epidemiologic studies related to healthcare procedures. Pakistan is enduring an HCV epidemic of historical proportions-one in every 20 Pakistanis is infected. HCV plays a major role in liver disease burden in this country, and HCV prevalence is high in all-risk populations. Most transmission appears to be driven by healthcare procedures. HCV treatment and prevention must become a national priority.

The structural HCV genes delivered by MPG cell penetrating peptide are directed to enhance immune responses in mice model

One of the significant problems in vaccination projects is the lack of an effective vaccine against hepatitis C virus (HCV). The goal of the current study is to evaluate and compare two DNA constructs encoding HCV core and coreE1E2 genes alone or complexed with MPG peptide as a delivery system for stimulation of antibody responses and IFN-γ secretion in Balb/c mice model. Indeed, MPG cell penetrating peptide was used to improve DNA immunization in mice. Our results demonstrated that MPG forms stable non-covalent nanoparticles with pcDNA-core and pcDNA-coreE1E2 at an N/P ratio of 10:1. The in vitro transfection efficiency of core or coreE1E2 DNA using MPG and TurboFect delivery systems was confirmed by western blot analysis. The results indicated the expression of the full-length core (∼21 kDa), and coreE1E2 (∼83 kDa) proteins using an anti-His monoclonal antibody. In addition, the expression of HCV core and coreE1E2 proteins was performed in bacteria and the purified recombinant proteins were injected to mice with Montanide 720 adjuvant. Our data showed that the immunized mice with HCV core and coreE1E2 proteins generated the mixture of sera IgG1 and IgG2a isotypes considerably higher than other groups. Furthermore, DNA constructs encoding core and coreE1E2 complexed with MPG could significantly induce IFN-γ secretion in lower concentrations than the naked core and coreE1E2 DNAs. Taken together, the DNA formulations as well as protein regimens used in this study triggered high-level IFN-γ production in mice, an important feature for the development of Th1 immune responses.

Expression and Purification of HCV Core and Core-E1E2 Proteins in Different Bacterial Strains

BACKGROUND

Hepatitis C virus (HCV) is a main public health problem causing chronic liver infection and subsequently liver cirrhosis and lethal hepatocellular carcinoma (HCC). Vaccination based on HCV capsid proteins has attracted a special interest for prevention of viral infections. The core protein is a basic and evolutionary most conserved protein, which regulates the cellular processes related to viral replication and pathogenesis. The envelope E1 and E2 proteins involve in generation of the infectious particles, viral entry by binding to a host cell receptor, and modulation of the immune responses.

OBJECTIVES

In current study, the efficient generation of recombinant core and core-E1E2 proteins was developed in bacterial expression systems.

MATERIALS AND METHODS

The expression of HCV core and core-E1E2 proteins was performed using prokaryotic pET-28a and pQE-30 expression systems in BL21/ Rosetta, and M15 strains, respectively. The recombinant proteins were purified using affinity chromatography under native conditions and also reverse staining method. Finally, the levels of recombinant proteins were assessed by BCA kit and spectrophotometer.

RESULTS

The data showed a clear band of ~573 bp for HCV core and ~2238 bp for core-E1E2 genes in agarose gel. Moreover, a ~21 kDa band of core protein and a ~83 kDa band of core-E1E2 protein were revealed in SDS-PAGE. The affinity chromatography could not purify the core and core-E1E2 proteins completely, because of low affinity to Ni-NTA bead in comparison with reverse staining method.

CONCLUSIONS

This study is the first report for purification of HCV core and core-E1E2 proteins using the reverse staining procedure with no need of any chromatography columns. The BL21 strain was more potent than Rosetta strain for HCV core protein in pET 28a expression system. Furthermore, M15 strain was suitable for expression of coreE1E2 in pQE-30 bacterial system.

Hepatitis C virus core antigen, an earlier and stronger predictor on sustained virological response in patients with genotype 1 HCV infection

Background

Earlier kinetics of serum HCV core antigen (HCVcAg) and its predictive value on sustained virological response (SVR) were investigated in patients with genotype 1 HCV infection during antiviral treatment.

Methods

In a multi-centered, randomized and positive drug-controlled phase IIb clinical trial on type Y peginterferon α-2b ( NCT01140997), forty-eight CHC patients who participated in pharmacokinetics were randomly divided into 4 cohorts and treated with PegIFNα (type Y peginterferon α-2b 90 μg, 135 μg, 180 μg and PegIFNα-2a 180 μg, respectively, once a week) and ribavirin (< 75 kg, 1000 mg daily and ≥ 75 kg, 1200 mg daily) for 48 weeks, and then followed up for 24 weeks. 32 patients infected with genotype 1 HCV and completed the whole process were included in this study. HCV RNAs were detected at baseline, and weeks 4, 12, 24, 48 and 72 using Cobas TaqMan. ARCHITECT HCVcAg was performed at 24, 48, 72, 96, 120 and 144 h in addition to the above time points. The receiver operating curves (ROCs) were performed to study the predictive values of HCVcAg decline on SVR.

Results

Following antiviral treatment, serum HCVcAg levels rapidly declined within the first week and correlated well with corresponding HCV RNA at baseline, weeks 4, 12, 24, 48 and 72 (r_s = 0.969, 0.928, 0.999, 0.983, 0.985 and 0.946, respectively, P < 0.001). All of the areas under the receiver operating curves (AUROCs) were more than 0.80 and showed good predictive power on SVR at 24, 48, 72, 96, 120 and 144 h. The144 h was the best predictive time point of HCVcAg decline on SVR because of its largest AUROC (more than 0.90).

Conclusions

Early kinetics of serum HCVcAg predicts SVR very well in genotype 1 CHC patients during antiviral treatment, and its reduction value at 144 h is an earlier and stronger predictor on SVR than rapid virological response and early virological response. (TRN: NCT01140997).

Expression of the full-length HCV core subgenome from HCV gentoype-1a and genotype-3a and evaluation of the antigenicity of translational products

BACKGROUND

Hepatitis C virus (HCV) infection is a major public health problem in India. Detection of HCV and its genotypes by simple and economic assays is a prime requirement in the planning of antiviral treatments for patients infected with this virus. Although commercial assays are available for the detection of both HCV RNA and genotypes, efforts aimed at the development of simple and economical systems for these measurements are still going on.

AIM

The present study was designed to clone and express the HCV CORE gene from HCV genotype-1a and genotype-3a and use the peptides to develop immunoassays for the detection of genotype-specific antibodies in sera samples.

METHODS

One hundred and thirty-five serum samples from patients with liver and renal diseases were screened for HCV RNA by real-time PCR, followed by HCV genotyping in RNA-positive sera by restriction fragment length polymorphism, sequencing, and phylogenetic analysis. The HCV CORE gene was amplified from sera carrying HCV genotype-1a and genotype-3a and cloned and expressed in the pET19b vector. The translational products were used to develop a western blot assay for the detection of genotype-specific anti-HCV antibodies.

RESULTS

The HCV CORE gene, from both genotypes, was cloned and expressed successfully, with production of a 26 kDa recombinant protein in either case. Using peptides in a western blot assay, 101 sera samples were tested for the anti-HCV CORE antibody. Each peptide showed a reaction with anti-HCV total antibody without showing any genotype-specific binding. This indicates that individual peptides obtained from different genotypes do not have a genotype-specific epitope to bind with antibodies.

CONCLUSION

Cloning and expression of the HCV CORE gene from genotype-1a and genotype-3a was successful. However, the peptides formed did not show genotype-specific binding with anti-HCV.