Typing of hepatitis C virus antibody with specific peptides in seropositive blood donors and comparison with genotyping of viral RNA

Discrepancy between Hepatitis C Virus Genotypes and NS4-Based Serotypes: Association with Their Subgenomic Sequences

Determination of hepatitis C virus (HCV) genotypes plays an important role in the direct-acting agent era. Discrepancies between HCV genotyping and serotyping assays are occasionally observed. Eighteen samples with discrepant results between genotyping and serotyping methods were analyzed. HCV serotyping and genotyping were based on the HCV nonstructural 4 (NS4) region and 5'-untranslated region (5'-UTR), respectively. HCV core and NS4 regions were chosen to be sequenced and were compared with the genotyping and serotyping results. Deep sequencing was also performed for the corresponding HCV NS4 regions. Seventeen out of 18 discrepant samples could be sequenced by the Sanger method. Both HCV core and NS4 sequences were concordant with that of genotyping in the 5'-UTR in all 17 samples. In cloning analysis of the HCV NS4 region, there were several amino acid variations, but each sequence was much closer to the peptide with the same genotype. Deep sequencing revealed that minor clones with different subgenotypes existed in two of the 17 samples. Genotyping by genome amplification showed high consistency, while several false reactions were detected by serotyping. The deep sequencing method also provides accurate genotyping results and may be useful for analyzing discrepant cases. HCV genotyping should be correctly determined before antiviral treatment.

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.

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

Background

Pakistan is facing a threat from hepatitis C infection which is increasing at an alarming rate throughout the country. More specific and sensitive screening assays are needed to timely and correctly diagnose this infection.

Methods

After RNA extraction from specimen (HCV-3a), cDNA was synthesized that was used to amplify full length core gene of HCV 3a. After verification through PCR, DNA sequencing and BLAST, a properly oriented positive recombinant plasmid for core gene was digested with proper restriction enzymes to release the target gene which was then inserted downstream of GST encoding DNA in the same open reading frame at proper restriction sites in multiple cloning site of pGEX4t2 expression vector. Recombinant expression vector for each gene was transformed in E. coli BL21 (DE3) and induced with IPTG for recombinant fusion protein production that was then purified through affinity chromatography. Western blot and Enzyme Linked Immunosorbant Assay (ELISA) were used to detect immuno-reactivity of the recombinant protein.

Results

The HCV core antigen produced in prokaryotic expression system was reactive and used to develop a screening assay. After validating the positivity (100%) and negativity (100%) of in-house anti-HCV screening assay through a standardized panel of 200 HCV positive and 200 HCV negative sera, a group of 120 serum specimens of suspected HCV infection were subjected to comparative analysis of our method with commercially available assay. The comparison confirmed that our method is more specific than the commercially available assays for HCV strains circulating in this specific geographical region of the world and could thus be used for HCV screening in Pakistan.

Conclusion

In this study, we devised a screening assay after successful PCR amplification, isolation, sequencing, expression and purification of core antigen of HCV genotype 3a. Our developed screening assay is more sensitive, specific and reproducible than the commercially available screening assays in Pakistan.

A cohort study of hepatitis C virus (HCV) infection in an HCV epidemic area of Japan: age and sex-related seroprevalence of anti-HCV antibody, frequency of viremia, biochemical abnormality and histological changes

We studied the age- and sex-specific prevalence of hepatitis C virus (HCV) infection and aminotransferase abnormalities as well as histological changes in the liver associated with HCV infection. Of the eligible 3,707 inhabitants aged 6 years and older in an HCV infection epidemic area 2,382 (64.3%) were examined. The anti-HCV positivity rate was 20.7% on average and increased according to age. Age was the most potential risk indicator for anti-HCV positivity by multiple stepwise regression analysis. The HCV RNA positivity rate in females with anti-HCV was significantly lower than that in males. However, as the age of females increased, the HCV RNA positivity rate became higher. The proportion of subjects with aminotransferase abnormalities among HCV RNA-positive subjects was significantly lower in females than males. Aminotransferase abnormalities significantly increased with age in females. In subjects with abnormal aminotransferase levels, nearly half of the HCV RNA-positive females were aged 50 or older and also nearly half of the male subjects showed CAH2B or liver cirrhosis, while most of the HCV RNA-positive females younger than 50 exhibited histological findings consistent with CPH. In conclusion, age was the principal risk indicator for HCV infection in this area. Females, especially those younger than 50, both biochemically and histologically showed less severity of HCV infection than males. Gender and age might have effects on the outcome of HCV related liver disease.

Hepatitis C virus serotype-specific core and NS4 antibodies in injecting drug users participating in the Amsterdam cohort studies

In the present study, the RIBA HCV serotyping SIA was evaluated with a cohort of injecting drug users. Serotyping may be a rapid and cost-effective method of determining genotypes in cohort studies. In this study, hepatitis C virus (HCV) antibody-positive sera from a cohort of 331 chronically infected injecting drug users, of which 167 were coinfected with human immunodeficiency virus (HIV), were serotyped by the RIBA HCV Serotyping SIA. Among the 331 specimens, serotype-specific antibodies were detected in 250 (sensitivity, 75. 5%), in which serotype 1 was predominant (57.2%), followed by serotype 3 (26.8%). Among the 331 specimens, 164 were HIV negative, and serotype-specific antibodies were detected in 151 (sensitivity, 92.1%), in which serotype 1 was predominant (59.6%), followed by serotype 3 (33.8%). For a subset of 58 samples taken from 19 chronically infected HCV seroconverters with a mean follow-up of 5 years, serotypes were compared with genotypes, which were determined by a line probe assay (HCV LiPa) and by direct sequencing of the products obtained by nested PCR of the 5' untranslated region. Among the 58 samples with known genotypes, serotype-specific antibodies were detected in 38 (total sensitivity, 65.5%), with a specificity of 78.9%. Thirty of these serotypeable samples revealed a serotype that corresponded to the genotype in the 58 samples (total positive predictive value, 51.7%). Of the 58 samples, 23 were coinfected with HIV, and when these were excluded, the total sensitivity increased to 76.5%, with a total specificity of 80.8% and a total positive predictive value of 61.8%. The serotyping assay showed a high total sensitivity (96.3%) for samples positive by HCV RIBA, version 3.0, with four bands. We conclude that the sensitivity of the RIBA HCV serotyping SIA is limited by the immunocompetence of the HCV-infected host. In general, samples from HIV-negative individuals containing genotype 1a had higher sensitivity, specificity, and concordance in the serotyping assay compared with genotyping, whereas samples containing genotype 3a were found to be more cross-reactive and untypeable. Therefore, the prevalence of genotypes other than genotype 1 could be underestimated if they are determined by serotyping, and improvements in specificity are recommended.