HCV virology and diagnosis.

Hepatitis C virus (HCV) infection is a major cause of severe liver disease including chronic hepatitis, cirrhosis and hepatocellular carcinoma. The HCV burden in public health is estimated at about 71 million people worldwide by World Health Organization (WHO) with at least 400,000 people that died every year from HCV disease [1]. New hepatitis C treatments with oral direct-acting antivirals (DAAs) showing high rates of response, with short treatment duration [2] have been available. HCV can now be eradicated with minimal side effects. Unfortunately, there is no vaccine yet available, but the development of a safe prophylactic vaccine remains a medical priority [3]. For this purpose, Hepatitis B-C subviral envelope particles can be produced by industrialized procedure. It seems to be very promising as this HBV-HCV vaccine candidate has been shown to elicit a broadly cross neutralizing activity against HCV [4]. Despite this revolution in the HCV-treatment, one of major challenge to achieve a global eradication of HCV remains to reduce the under diagnosis. The low rate of diagnosis is a major obstacle in resources limited countries and is mainly due to the cost of molecular tools, that are essential to diagnose and follow chronic HCV infection. In another hand, the mild clinical symptoms observed in HCV chronic disease, may explain that the majority of HCV infected individuals are unaware of their infection, because HCV testing is not generalized, like it is for HIV. HCV was discovered in 1989 after many years of work, by several researchers, who recently obtained the Nobel price [5-7]. This major discovery allowed the description of the HCV genome and later on of the virus replication and cell cycle, and also, importantly, the development of diagnostic tests for the detection of HCV antibodies (Ab) and RNA who were a priority in transfusion. In this review, we will try to get into the virology and cell biology of HCV. Thereafter, we will discuss the different categories of laboratory tests to diagnose/explore HCV infected subjects.

Influence of the HCV subtype on the virological response to pegylated interferon and ribavirin therapy.

The hepatitis C virus genotype is considered to be the most important baseline predictor of a sustained virological response in patients with chronic hepatitis C treated with pegylated interferon and ribavirin. The influence of the subtype on the sustained virological response was investigated in patients infected with genotypes 1, 4, 5, or 6. This study was done on 597 patients with chronic hepatitis C who were given pegylated interferon and ribavirin for 48 weeks. The overall rate of sustained virological response in the 597 patients was 37.8%. Univariate analysis indicated that the sustained virological response of patients infected with subtype 1b (39%) tended to be higher than that of patients infected with subtype 1a (30.6%; P = 0.06) and it was similar to those patients infected with subtypes 4a (51.3%; P = 0.12) or 4d (51.7%; P = 0.16). Multivariate analysis indicated that five factors were independently associated with sustained virological response: the age (OR 0.97; 95% CI = 0.95-0.99), absence of cirrhosis (OR: 2.92; 95% CI = 1.7-5.0; P < 0.01), absence of HIV co-infection (OR: 2.08; 95% CI = 1.2-3.5; P < 0.01), low baseline plasma HCV RNA concentration (OR: 1.74; 95% CI = 1.2-2.6; P < 0.01), and the subtype 1b (OR: 1.61; 95% CI = 1.0-2.5; P = 0.04) or subtypes 4a and 4d (OR: 2.03; 95% CI = 1.1-3.8; P = 0.03). In conclusion, among difficult-to-treat genotypes, the subtype 1a is associated with a lower response to anti-HCV therapy than subtypes 1b, 4a, and 4d.

Quasispecies evolution in NS5A region of hepatitis C virus genotype 1b during interferon or combined interferon-ribavirin therapy.

AIM: To evaluate the implication of substitutions in the hepatitis C virus (HCV) non-structural 5A (NS5A) protein in the resistance of HCV during mono-interferon (IFN) or combined IFN-ribavirin (IFN-R) therapy. Although NS5A has been reported to interact with the HCV RNA-dependent RNA polymerase, NS5B, as well as with many cellular proteins, the function of NS5A in the life cycle of HCV remains unclear. METHODS: HCV quasispecies were studied by cloning and sequencing of sequential isolates from patients infected by HCV genotype 1b. Patients were treated by IFN-alpha2b for 3 mo followed by IFN-alpha2b alone or combined IFN-R therapy for 9 additional months. Patients were categorized into two groups based on their response to the treatments: 7 with sustained virological response (SVR) (quasispecies = 150) and 3 non-responders (NR) to IFN-R (quasispecies = 106). RESULTS: Prior to treatment, SVR patients displayed a lower complexity of quasispecies than NR patients. Most patients had a decrease in the complexity of quasispecies during therapy. Analysis of amino acids substitutions showed that the degree of the complexity of the interferon sensitivity-determining region (ISDR) and the V3 domain of NS5A protein was able to discriminate the two groups of patients. Moreover, SVR patients displayed more variability in the NS5A region than NR patients. CONCLUSION: These results suggest that detailed molecular analysis of the NS5A region may be important for understanding its function in IFN response during HCV 1b infection.

[Autoimmune thrombopenia associated with hepatitis B reactivation (reverse seroconversion) after autologous hematopoietic stem cell transplantation]. / Thrombopénie auto-immune associée à une réactivation virale B (séroréversion HBs) après autogreffe de moelle.

We report a case of autoimmune thrombocytopenia associated with acute reverse seroconversion of hepatitis B in a patient who was initially hepatitis B virus surface antigen negative and hepatitis B virus surface antibody positive. Reactivation occurred 9 months after chemotherapy with anti-CD 20 monoclonal antibodies and autologous hematopoietic stem cell transplantation for lymphoma had been performed. After non specific polyglobulin injections and treatment with adefovir dipivoxil, thrombocytopenia and viral replication were controlled. Seroconversion for both HBe and HBs occurred at 5 months. Adefovir was stopped 4 months later with no relapse during fifteen months of follow-up. This case shows that patients who have had previous contact with hepatitis B virus should be monitored if they become immunosuppressed, even if anti-HBs were initially present.

[Severe autoimmune neutropenia and thrombopenia associated with chronic C hepatitis: effect of antiviral therapy]. / Neutropénie et thrombopénie auto-immunes sévères associées à une hépatite chronique C: effet du traitement antiviral.

We report the case of a 45-year-old man admitted for severe autoimmune thrombopenia and neutropenia associated with chronic viral C hepatitis. After failed, intravenous gammaglobulin and corticosteroid therapy antiviral treatment with interferon and ribavirin was given for one year. Thrombopenia improved progressively during antiviral therapy and worsened after the end of treatment. Neutropenia improved during antiviral therapy. Two years after the end of treatment, serum RNA-HCV was positive, white cell count was normal and platelet count was 77 G/L. In conclusion, these results suggest that antiviral therapy may be useful in patients with auto-immune cytopenia associated with viral hepatitis C infection.

Evolutionary history of hepatitis C virus genotype 5a in France, a multicenter ANRS study.

The epidemic history of HCV genotype 5a is poorly documented in France, where its prevalence is very low, except in a small central area, where it accounts for 14.2% of chronic hepatitis C cases. A Bayesian coalescent phylogenetic investigation based on the E1 envelope gene and a non-structural genomic segment (NS3/4) was carried out to trace the origin of this epidemic using a large sample of genotype 5a isolates collected throughout France. The dates of documented transmissions by blood transfusion were used to calibrate five nodes in the phylogeny. The results of the E1 gene analysis showed that the best-fitting population dynamic model was the expansion growth model under a relaxed molecular clock. The rate of nucleotide substitutions and time to the most recent common ancestors (tMRCA) of genotype 5a isolates were estimated. The divergence of all the French HCV genotype 5a strains included in this study was dated to 1939 [95% HPD: 1921-1956], and the tMRCA of isolates from central France was dated to 1954 [1942-1967], which is in agreement with epidemiological data. NS3/4 analysis provided similar estimates with strongly overlapping HPD values. Phylodynamic analyses give a plausible reconstruction of the evolutionary history of HCV genotype 5a in France, suggesting the concomitant roles of transfusion, iatrogenic route and intra-familial transmission in viral diffusion.

Unique NS5b hepatitis C virus gene sequence consensus database is essential for standardization of genotype determinations in multicenter epidemiological studies.

A multicenter study of NS5b hepatitis C virus (HCV) genotype determination involving 12 laboratories demonstrates that any laboratory with expertise in sequencing techniques would be able to provide a reliable HCV genotype for clinical and epidemiological purposes as long as they are provided a consensus reference sequence database.

Mutations within the hepatitis C virus genotype 1b E2-PePHD domain do not correlate with treatment outcome.

The hepatitis C virus (HCV) envelope protein 2 (E2) interacts in vitro with the interferon alpha (IFN-alpha)-inducible double-stranded RNA-activated protein kinase, suggesting a possible mechanism by which HCV may evade the antiviral effects of IFN-alpha. Variability in the part of the HCV E2 gene encoding the carboxy-terminal part of the protein, which includes the interaction domain (E2-PePHD), was explored in 25 patients infected with HCV genotype 1b and receiving IFN-alpha therapy. PCR products were generated and sequenced for 15 patients with a sustained response and for 10 patients with no virological response after treatment with IFN-alpha and ribavirin. PePHD amino acid sequences were obtained for isolates from serum collected before and during treatment, after 2 months in responders, and after 6 months in nonresponders. Quasispecies analysis of the pretreatment PePHD region was performed for isolates from patients displaying amino acid substitutions in this domain on direct sequencing. The E2-PePHD sequence was highly conserved in both resistant and susceptible genotype 1b strains and was identical to the prototype HCV type J sequence. No significant emergence of PePHD mutants during therapy was observed in our clonal analysis, and sporadic mutations and treatment outcomes were not found to be correlated. The PePHD sequence before or during treatment cannot be used to predict reliably the outcome of treatment in HCV type 1b-infected patients.

Usefulness of the hepatitis C virus core antigen assay for screening of a population undergoing routine medical checkup.

We studied the usefulness of the recently designed Trak-C assay for the detection and quantification of the hepatitis C virus (HCV) core antigen (Ag) for the screening of HCV infection in 4,201 subjects selected from 74,150 consecutive volunteers undergoing routine medical checkups. Subjects were selected for screening because they had risk factors (group II, n = 321) and/or elevated alanine transaminase activity (group I, n = 3847). Initially, the anti-HCV antibody assay and the Trak-C assay were performed on each patient. Subsequently, the Trak-C assay was performed only when the anti-HCV enzyme immune assay (EIA) was positive. Positive samples were further evaluated for anti-HCV antibodies by a third-generation strip immunoblot assay and for HCV RNA. Four samples (1.2%) from group II and 113 (2.9%) from group I were anti-HCV EIA positive. We also tested 33 subjects who previously tested positive for anti-HCV in our medical center. Among the 150 anti-HCV EIA-positive samples, the HCV core Ag result was in accord with the HCV RNA result in 146 cases (97.3%). When the EIA result was positive, the HCV core Ag concentration and the HCV RNA load were correlated (r(2) = 0.78; P < 0.001). Four samples with low viral loads were Trak-C negative but HCV RNA positive. Among the 2,395 anti-HCV EIA-negative serum samples collected during the first part of the study, 17 (0.7%) were found to contain very low levels of HCV core Ag (<8.5 pg/ml, the cutoff value being 1.5 pg/ml). All these samples were HCV RNA negative and considered to be false positives. This was confirmed by HCV core Ag neutralization analysis. The HCV core Ag assay is a useful method in the screening strategy of HCV infection and provides a reliable means of distinguishing between current and cleared HCV infections that is well correlated with HCV RNA testing.

Comparison of hepatitis C virus NS5b and 5' noncoding gene sequencing methods in a multicenter study.

A national evaluation study was performed in 11 specialized laboratories with the objective of assessing their capacities to genotype hepatitis C virus (HCV) and define the applicability of a given genotyping method. The panel consisted of 14 samples positive for HCV RNA of different genotypes (including 3 samples with two different artificially mixed genotypes) and 1 HCV-negative sample. Seventeen sets of data were gathered from the 11 participating laboratories. The sensitivities ranged from 64.3 to 100% and from 42.7 to 85.7% for the methods that used sequencing of the NS5b region and the 5' noncoding (5' NC) region, respectively. When the data for the artificially mixed samples were excluded, NS5b genotyping gave correct results for 80% of the samples, 1.7% of the samples were misclassified, and 18.3% of the samples had false-negative results. By 5' NC-region genotyping methods, 58.3% of the results were correct, 29.7% were incomplete, 8.3% were misclassifications, 1.2% were false positive, and 2.4% were false negative. Only two procedures based on NS5b sequencing correctly identified one of the three samples with mixtures of genotypes; the other methods identified the genotype corresponding to the strain with the highest viral load in the sample. Our results suggest that HCV 5' NC-region genotyping methods give sufficient information for clinical purposes, in which the determination of the subtype is not essential, and that NS5b genotyping methods are more reliable for subtype determination, which is required in epidemiological studies.

Significance of pretreatment analysis of hepatitis C virus genotype 1b hypervariable region 1 sequences to predict antiviral outcome.

The heterogeneity of hypervariable region 1 (HVR1), located at the amino terminus of the E2 envelope, may be involved in resistance to alpha interferon (IFN-alpha) treatment. We investigated whether peculiar HVR1 domain profiles before treatment were associated with the maintenance of sensitivity or the appearance of resistance to treatment. Fifteen patients infected with hepatitis C virus genotype 1b and treated with IFN with or without ribavirin were selected. Ten responded to treatment (groups R1 and R2) and five did not (group NR). The amino acid sequences of 150 naturally occurring HVR1 variants present in the serum before therapy were compared in relation to treatment outcome. HVR1 variants from the NR group contained a constant nonantigenic amino acid segment that was not found in HVR1 variants from the R groups.

Subtype B human immunodeficiency virus (HIV) type 1 mutant that escapes detection in a fourth-generation immunoassay for HIV infection.

We report a case of human immunodeficiency virus (HIV) type 1 infection not detected by a highly sensitive combined antigen-antibody assay. The virus was a subtype B strain harboring a unique sequence within the immunodominant epitope of the transmembrane glycoprotein. Immunochemical analysis indicated that this sequence was probably responsible for the failure to detect HIV antibodies.