Unravelling hepatitis C virus replication from genome to function.

Center for the Study of Hepatitis C, The Rockefeller University, 1230 York Avenue, New York, New York 10021, USA.
Nature (Impact Factor: 42.35). 09/2005; 436(7053):933-8. DOI: 10.1038/nature04077
Source: PubMed

ABSTRACT Since the discovery of the hepatitis C virus over 15 years ago, scientists have raced to develop diagnostics, study the virus and find new therapies. Yet virtually every attempt to dissect this pathogen has met with roadblocks that impeded progress. Its replication was restricted to humans or experimentally infected chimpanzees, and efficient growth of the virus in cell culture failed until very recently. Nevertheless hard-fought progress has been made and the first wave of antiviral drugs is entering clinical trials.

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Introduction. Hepatitis C virus (HCV) is a human pathogen which represents a major public health threat. Worldwide, 170 million people are chronically infected with HCV, and they are in danger of developing life-threatening liver diseases, including liver cirrhosis and hepatocellular carcinoma. During the last years this problem has become important also in Latvia, as approximately 80 000 inhabitants of Latvia are already infected with HCV or are hidden carriers of it. IFN-α monotherapy is effective only in 10–20% of cases, therefore it is very important to establish HCV genome changes during antiviral therapy. Despite the detailed knowledge of the molecular and structural biology of HCV, the pathogenesis of infection remains unclear. Aim. The main aim of the work was to monitor the changes of HCV core, HVR1, and NS5A-ISDR regions during the course of antiviral therapy. Materials and methods. 113 sera of patients with chronic hepatitis C, which were treated with IFN-α (3 mill. IU/3x per week) and ribavirin (1000–1200 mg/per day), were tested for the presence of HCV RNA using RT–PCR technique. RT–PCR product was taken for PCR1 and, after polymerase chain reaction, PCR1 product was used for nested PCR2 reaction. Positive PCR2 samples were purified with DNA Extraction kit (Fermentas, Lithuania) and used in sequencing reaction by ABI Prism Genetic Analyzer 3900. Sequencing data were processed with Contig Express and edited manually by Bioedit Sequence Alignment. DNA distance matrices were calculated by using the DNADIST DNA distance matrix. Phylogenetic trees were generated by the Phylip software. Results and discussion. 113 patients’ sera were checked: 53 samples were HCV RNA positive, 60 samples of sera were HCV RNA negative. Two patients’ sera were HCV–RNA negative in all samples, and three patients’ sera were HCV RNA positive only in one sample. Nucleotide sequence of HCV genome core, HVR1, and ISDR regions were analyzed and the sequences as reset HCV in all samples of patient were assigned to genotype 1, 1b subtype. Main genotypes represented in Latvia are 1, 2 and 3, but the subtype 1b is prevalent. By calculating the genetic distances and comparing them, it was concluded that changes in HCV core region have occurred during the course of antiviral therapy. The genetic distance of patients 1H, 4H, 7H and 10H was fluctuating. However, for patients 3H, 6H and 14H this trend was not observed. Fluctuating changes in HCV genome can be modulated by the immune system pressure of patients. HVR1 genetic distance of patients 1H genome was fluctuating, but 9H and 14H HVR1 regions did not change during antiviral therapy. In case of patient 10H, genetic distance of samples during IFN-α therapy was very high. Therefore, it is not excluded that different HCV quasispecies dominated in the samples. Distribution of HCV quasispecies might have important biological consequences. Genetic heterogeneity of the HVR1 may allow HCV to escape immune pressure and to establish chronic infection. Mutations within the HVR1 region are believed to be associated with viral persistence via immune escape mechanisms. Genetic distances of ISDR sequences in patients 10H, 11H and 14H appeared only between the first and the following samples. In 1H, the genetic distance was fluctuating. A plausible explanation for the NS5A-ISDR changes lies in the fact that the structure of this region is associated with IFN-α therapy outcome and that this region is changing during therapy. However, there are many studies which do not support this assumption. NS5A is indeed known to contain a high concentration of T- and B-cell epitopes. Conclusions. We observed different HCV genome changes during IFN-α+ribavirin therapy. These mutations found as the result of IFN-α therapy remain unclear, because various factors have influence on its: patients’ age, sex, level of IFN a/b receptors, cytokine sensitivity, viral load, virus origin, peculiarities of macroorganism metabolism and others.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Hepatitis is leading cause of morbidity and mortality in the world, and especially in Pakistan due to high prevalence. Around 7.4% of Pakistani population is suffering from chronic hepatitis B and C, which is highest in Southeast Asia region. Unnecessary high use of injections, use of contaminated razors, intravenous drug users (IDUs) and acupuncture needles are some of the leading factors of infection in Pakistan. HBV is a DNA type virus with a genome size of 3.2kb while HCV is positive single stranded RNA type virus with a genome size of 9.6kb and most prevalent type of hepatitis C in Pakistan is 3a. Majority of patients (>80%) remain asymptomatic with no clinical signs of disease. Chronic hepatitis results in liver fibrosis, cirrhosis, hepatocellular carcinoma and other complications which are very hard to treat. Hepatitis B vaccine is available in the market which gives lifelong protection while due to high mutation rate of HCV, there is no vaccine for HCV yet. As treatment of hepatitis is very expansive so government should have focus on preventive measures to avoid the further spread of infection and this can be achieved by proper educational and awareness campaigns about the disease.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Chronic Hepatitis C virus (HCV) infection is the leading cause of advanced liver disease worldwide. The virus successfully evades host immune detection and for many years has hampered efforts to find a safe, uncomplicated, and reliable oral antiviral therapy. Initially, interferon and ribavirin therapy was the treatment standard of care, but it offered limited performance across the wide spectrum of HCV disease and was fraught with excessive and often limiting side effects. Sofosbuvir (SOF) is a potent first-in-class nucleoside inhibitor that has recently been approved for treatment of HCV. The drug has low toxicity, a high resistance barrier, and minimal drug interactions with other HCV direct-acting antiviral agents such as protease inhibitors or anti-NS5A agents. SOF is safe and can be used across different viral genotypes, disease stages, and special patient groups, such as those coinfected with human immunodeficiency virus. When used in combination with ribavirin or another direct-acting antiviral agent, SOF has revolutionized the HCV treatment spectrum and set the stage for nearly universal HCV antiviral therapy. More so than any other anti-HCV drug developed to date, SOF offers the widest applicability for all infected patients, and new regimens will be tailored to maximize performance.
    Pharmacogenomics and Personalized Medicine 01/2014; 7:387-98. DOI:10.2147/PGPM.S52629

Full-text (2 Sources)

Available from
Jun 1, 2014

Brett Lindenbach