Variations in the core region of hepatitis C virus genomes in patients with chronic hepatitis

Alanine transaminase levels in the year before pregnancy predict the risk of hepatitis C virus vertical transmission

Vertical transmission is the most common route of hepatitis C virus (HCV) infection in children. Transmission risk factors have been described, but most risk factors can only be evaluated using expensive laboratory exams. The aim of the present study was to evaluate whether maternal alanine transaminase (ALT) levels before pregnancy correlate with HCV vertical transmission. Seventy-four transmitting and 403 nontransmitting mothers were evaluated. All mothers enrolled had two ALT determinations in the last year before pregnancy, at least 6 months apart. Mothers were divided into two groups: mothers with persistently normal serum ALT levels and mothers with abnormal ALT levels. In the second group both mothers with constantly raised or with fluctuating ALT levels (one normal and one raised determination) were included. ALT was defined as raised if higher than twice the upper limit of normal. Abnormal ALT levels were found in 39/74 (52.7%) HCV transmitting mothers and in 146/403 (32.6%) nontransmitting mothers (P = 0.008; relative risk 1.96; 95% confidence limits 1.19-3.23). The risk of transmission from mothers with constantly raised ALT levels was more evident than that from mothers with fluctuating ALT levels. Increased ALT levels may reflect a more severe liver disease and a higher viral load, factors known to be associated with vertical transmission. ALT determination, a simple, widely available and inexpensive test, may help in identifying mothers with an increased risk of HCV vertical transmission.

Dynamics of serum hepatitis C virus load and quasispecies complexity during antiviral therapy in patients with chronic hepatitis C

BACKGROUND

Hepatitis C virus (HCV) infection is a dynamic process during which viral genetic variants continuously develop as a result of the virus adaptation to the host's immune system. The level of viremia and the complexity of the hypervariable region 1 (HVR 1) quasispecies of hepatitis C virus during antiviral therapy reflect the dynamic balance between the viral and host components in response to therapy.

OBJECTIVE

The aim of the study was to evaluate the dynamics of HCV viremia and the complexity of the HVR 1 quasispecies during the induction phase of a triple combination therapy regimen in nonresponders to earlier anti-HCV treatment.

STUDY DESIGN

Ten patients with chronic hepatitis C undergoing antiviral combination therapy with interferon-alpha, ribavirin, and amantadine were studied. The serum HCV RNA level was monitored by a quantitative RT-PCR assay up to 3 months after start of treatment. The HVR 1 quasispecies complexity was analysed by an "in house" nested RT-PCR mediated single-strand conformation polymorphism (SSCP) assay.

RESULTS

Baseline serum HCV RNA levels ranged from 1.94x10(6) to 5.53x10(6) copies/ml. In all patients, HCV subtype 1b was found. At the start of therapy, the SSCP assay revealed a high complexity pattern (at least six SSCP bands) in all patients. None of the patients responded within 4 weeks of treatment, however, the serum HCV RNA level decreased by one to two logs in eight patients. At week 4 after start of treatment, there was a decrease of SSCP bands in five patients. In four patients, SSCP bands remained unchanged and in one patient SSCP bands increased. At month 3 after start of treatment, serum HCV RNA was not detectable in one patient.

CONCLUSION

Because of the low number of patients involved in this study, prediction of therapeutical success based on the quasispecies complexity was not possible. Larger studies are urgently needed.

Hypervariable region 1 of hepatitis C virus genome and response to interferon therapy

The relationship between the complexity of the hypervariable region 1 (HVR1) quasispecies of hepatitis C virus (HCV) and responsiveness to interferon-alpha (IFN) therapy was studied in patients with chronic hepatitis C. Twelve HCV-RNA-positive patients were treated daily with high dose IFN and ribavirin for 4 weeks, and then with IFN 3 MIU (Million International Units) TIW (three times per week) and ribavirin for 6 months. The HVR1 quasispecies complexity was analyzed by nested polymerase chain reaction-mediated single-strand conformation polymorphism (SSCP). The baseline HCV-RNA levels in the study group ranged from 10(6) to 10(7) copies/ml. All patients exhibited HCV genotype 1 b. Initial SSCP analysis revealed four (33.3%) patients with a low complexity pattern (SSCP bands < or =4) and eight (66.6%) patients with high complexity pattern (SSCP bands >4). After 4 weeks of IFN therapy, one patient became HCV negative, and among those remaining positive, the HCV-RNA levels decreased by 2 to 3 logs and the number of SSCP decreased by 2 to 3 bands per sample. After 6 months of IFN therapy, five (41.7%) patients became HCV-RNA-negative. Seven (58.3%) patients did not respond to IFN therapy with sustained viral load from 10(3) to 10(5) copies/ml, and high complexity SSCP patterns. Our data support the HVR quasispecies complexity to be an independent predictive factor for IFN responsiveness in patients infected with HCV.

Time-related changes in full-length hepatitis C virus sequences and hepatitis activity

The activity of hepatitis varies in chronic hepatitis C virus (HCV) infection. Some patients show persistently normal serum alanine aminotransferase (ALT) values, whereas the others show high-ALT values and progress to liver cirrhosis or hepatocellular carcinoma. However, virological mechanisms causing hepatitis have not fully been elucidated. We analyzed serial changes in full-length HCV sequences in 10 patients with various profiles of hepatitis activity. In the nonstructural 5A (NS5A) and NS5B, the rate of amino acid changes, as well as the proportion of nonsilent ones, was low in patients with normal ALT values compared with those with abnormal ALT (for the rate of amino acid changes, 0 x 10(-3) vs 3.19 x 10(-3) changes/site/year (P = 0.037) in NS5A and 0 x 10(-3) vs 1.22 x 10(-3) changes/site/year (P = 0.023) for NS5B, for the proportion of nonsilent changes, 4 vs 22% (P = 0.017) in NS5A and 0 vs 16% (P = 0. 039) in NS5B). Also, the flare-up of hepatitis coincided with higher nucleotide/amino acid substitution rates in NS5B. In conclusion, the genomic structures of the NS5A and NS5B regions may correlate with hepatitis activity in chronic hepatitis C.

Duration of HCV infection as a predictor of nonresponse to interferon

Duration of hepatitis C virus (HCV) infection is a key feature in determining responsiveness to interferon (IFN). Studies assessing its value as a predictive factor in chronic HCV infection show that a long duration of infection reduces the likelihood of a sustained response to IFN (defined as ALT normalization and clearance of serum HCV-RNA). The effect of HCV infection duration is independent of the presence of cirrhosis and level of HCV viremia. Meta-analysis of IFN trials in acute HCV infection shows an obvious effect of the drug on long-term ALT normalization and HCV-RNA clearance. Treatment of HCV infection during the acute or early chronic phase could therefore maximize therapeutic effectiveness.

Clinical relevance of hepatitis C virus quasispecies

It has been shown that hepatitis C virus (HCV) populations in infected individuals are composed of quasispecies with diverse mutations. The analysis of these variants may reveal mechanisms of the persistence of HCV infection, carcinogenesis and resistance to antiviral therapy. Recently, genetic features of interferon-resistant HCV have been elucidated through the analysis of interferon-resistant quasispecies, making it possible to predict interferon efficacy by detecting interferon-resistant strains.