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Liver Unit, Institut de Malalties Digestives, Departament de Medicina (IMD), Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Hospital Clinic, University of Barcelona, Spain
Correspondence
Juan-Carlos Saiz
jcsaiz{at}inia.es
The quasispecies nature of hepatitis C virus (HCV) may have important implications concerning resistance to antiviral agents. To determine whether HCV NS5A quasispecies composition and dynamics are related to responsiveness to combined interferon (IFN) and ribavirin therapy, extensive sequence analyses of cloned RT-PCR amplification products of HCV-1b NS5A quasispecies of sequential isolates from 15 treated (nine sustained responders and six non-responders) and three untreated patients were performed. Accumulation of mutations in NS5A during therapy was relatively frequent in the V3 domain, but unusual elsewhere. Amino acid changes were the result of the imposition of minor variants that were already present before treatment and always occurred within the first week of therapy. Before treatment, the complexity and diversity of quasispecies were lower in isolates from responders than in those from non-responders, particularly in the V3 domain, where differences in nucleotide entropy (0·35 vs 0·64, P=0·003), genetic distance (0·0145 vs 0·0302, P=0·05) and non-synonymous substitutions (0·0102 vs 0·0203, P=0·036) were statistically significant. These differences became more apparent during treatment, because complexity and diversity remained stable or tended to increase in non-responders, whereas they tended to decrease in responders. These observations suggest that the composition and dynamics of HCV NS5A quasispecies, particularly in the V3 domain, may play a role in the response to combined IFN/ribavirin therapy.
The GenBank/EMBL/DDBJ accession numbers for the HCV sequences reported in this study are AY378328AY378694, AY378705AY379066, AY381300AY381643 and AY381644AY381994.
Present address: Departamento de Biotecnología, Instituto Nacional de Investigaciones Agrarias (INIA), Ctra Coruña km 7·5, 28040 Madrid, Spain.
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P. Munoz de Rueda, J. Casado, R. Paton, D. Quintero, A. Palacios, A. Gila, R. Quiles, J. Leon, A. Ruiz-Extremera, and J. Salmeron Mutations in E2-PePHD, NS5A-PKRBD, NS5A-ISDR, and NS5A-V3 of Hepatitis C Virus Genotype 1 and Their Relationships to Pegylated Interferon-Ribavirin Treatment Responses J. Virol., July 1, 2008; 82(13): 6644 - 6653. [Abstract] [Full Text] [PDF] |
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