Hepatitis C virus (HCV) is a major cause of liver disease. Knowledge of HCV variability is crucial for clinical and epidemiological analysis. HCV genotype 4 (HCV-4) has become increasingly prevalent in European countries, including France, in recent years. The present study investigates the heterogeneity of HCV-4 in south-western France by phylogenetic analysis of NS5B sequences from 166 patients. The E2 region of 90 strains was also analysed. Genotype 4 accounts for 7?4 % of HCV infections in this area. Analysis of the NS5B region revealed 12 subtypes and the NS5B and E2 phylogeny data were congruent, except for one strain. The epidemiological data indicated two main groups of patients. One included intravenous drug users (IVDUs) of French origin, who were infected by homogeneous strains of subtypes 4a or 4d. The second group comprised non-IVDU patients who were infected with heterogeneous strains. This group was subdivided into patients of French origin, who were infected with eight subtypes, and patients from non-European countries (Central Africa or the Middle East), who were mainly infected with 4f, 4k, 4r and other subtypes; they showed the greatest genetic heterogeneity. This study of a large cohort of patients shows the great diversity of HCV-4 strains, and that these subtypes have spread differently.

Hepatitis C Virus (HCV) is classified into six genotypes. Genotype 4 is now spreading in Europe, especially among drug users, who are often infected with both HCV and the human immunodeficiency virus (HIV). Previous studies have shown that HCV-4 responds poorly to interferon. Pegylated interferon (peg-IFN) associated with ribavirin is now the most effective treatment for eradicating the virus. We have now studied the response of HCV-4 to peg-IFN and ribavirin and investigated the influence of HIV infection on anti-HCV therapy. Twenty-eight patients infected with HCV-4 were given peg-IFN plus ribavirin for 48 weeks. Patients infected with HCV alone tended to have a better initial response (66%) than patients infected with both HCV and HIV (30%, P = 0.06) and eradication was better (50%) than in doubly infected patients (15%, P = 0.06). After controlling for major factors influencing virus response, the virus response 12 weeks after the beginning of treatment in patients infected with HCV-4 (50%) was similar to that of patients infected with genotype 1 (53%) and lower than that of patients infected with genotypes 2 or 3 (82%, P < 0.05). The response 24 weeks after the end of therapy in patients infected with HCV-4 (32%) was similar to that of patients infected with HCV-1 (28%) and lower than that of patients with HCV-2 or HCV-3 (62% P < 0.05). These results indicate that HCV-4 patients should be considered to be difficult-to-treat.

In untreated hepatitis virus (HCV)-positive renal transplant patients, the rate of liver fibrosis progression is low. In contrast, in those treated by ribavirin monotherapy, liver fibrosis score increased significantly after only 1 year of ribavirin monotherapy. The aim of this study was to identify the factors that might contribute to accelerate liver fibrosis progression in this population. Eleven patients were included in the study. Intrahepatic transforming growth factor (TGF)-beta, interferon (IFN)-gamma, and interleukin (IL)-10 mRNA quantification determined by real-time reverse transcription-polymerase chain reaction (RT-PCR) were similar before and after ribavirin therapy. The number of amino acid substitutions observed in the hypervariable region (HVR)-1 of the HCV genome between baseline and 1 year after ribavirin monotherapy was low, i.e., 3 (1-11) amino acid substitutions, suggesting the absence of a high selection pressure induced by ribavirin. In contrast, due to ribavirin-induced hemolysis, there was a significant increase in serum ferritin levels (P = 0.02) and in intrahepatic iron deposition (P = 0.04). Transferrin level and total iron-binding capacity decreased significantly during ribavirin monotherapy (P = 0.004). The increased liver fibrosis observed in renal transplant patients receiving ribavirin monotherapy could be related to ribavirin-induced anemia. Severe chronic hemolysis is responsible for iron overload, liver iron deposition, and an acceleration in the progression of liver fibrosis.

The heterogeneity of the envelope 2 (E2) gene of the hepatitis C virus (HCV) was involved in the sensitivity of HCV to interferon-alpha (IFN-alpha). To assess the factors leading to virus eradication by IFN-alpha, patients whose first treatment by IFN-alpha failed and who had virus eradication after a second treatment were studied. These patients were paired with subjects in whom both treatments failed. The phosphorylation homology domain of the E2 gene (E2-PHD) had no sequence variation between the two stages in both groups of patients. Therefore, this region has no clinical predictive value within a specific genotype. The hypervariable region 1 (HVR1) was analyzed by cloning and sequencing 20 clones per sample. Comparison of samples showed that the change in quasispecies induced by the first IFN-alpha therapy could be associated with virus elimination obtained after a second treatment. The greater proportion of nonsynonymous mutations that was noted before the second treatment in responders suggest that pretherapeutic immune response is a major factor determining virus elimination and that the immune status of these patients changed between the first and the second treatment.

Numerous studies reported that patients infected by the genotype 1 of hepatitis C virus (HCV) and/or with a high baseline viral load responded poorly to antiviral therapy. Study of viral kinetics has provided clues to the understanding of non-response to alpha-interferon (IFN-alpha)-based therapy. The objective of this study was to clarify the influence of viral factors such as the genotype and baseline viral load on HCV resistance to treatment through the study of their impact on the first phase of viral decline. HCV RNA levels were determined frequently following the administration of 3 million units of IFN-alpha in 22 chronic HCV carriers. The evolution of HCV RNA level over 24 hr was different in genotype 1-infected patients, compared to that in patients infected by other genotypes. The viral load decline at 24 hr was lower in patients with genotype 1. Patients with a high baseline viral load exhibited a viral dynamics different from patients with a lower level of viremia; the extent of the first phase was also lower in these patients. Non-responder patients had a slower viral decay on day 1 of therapy than patients who cleared the virus under treatment. In conclusion, 24 hr HCV dynamics is regulated by genotype and baseline viral load. Genotype 1 strains and those that produce high viral loads are the most resistant to the antiviral action of IFN-alpha. Resistant HCV strains could be distinguished from sensitive viruses as early as a few hours after the beginning of the treatment.