Quasispecies Heterogeneity of the Carboxy-Terminal Part of the E2 Gene Including the PePHD and Sensitivity of Hepatitis C Virus 1b Isolates to Antiviral Therapy

• Published in: Virology (New York, N.Y.) Vol. 289; no. 1; pp. 150 - 163
• Main Authors: Sarrazin, Christoph, Bruckner, Markus, Herrmann, Eva, Rüster, Brigitte, Bruch, Katharina, Roth, W.Kurt, Zeuzem, Stefan
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 10.10.2001
• Subjects: Adult; AE2 gene; AE2 protein; Aged; Amino Acid Sequence; Antiviral Agents - therapeutic use; DNA-Binding Proteins - chemistry; DNA-Binding Proteins - genetics; double-stranded RNA-activated protein kinase (PKR)-binding domain; double-stranded RNA-activated protein kinase (PKR)-eIF2α phosphorylation homology domain (PePHD); E2 gene; E2 protein; eIF-2 Kinase - chemistry; eIF-2 Kinase - genetics; envelope (E)2 protein; Genes, Viral; genetic complexity; genetic diversity; Genetic Variation; Hepacivirus - classification; Hepacivirus - drug effects; Hepacivirus - genetics; hepatitis C virus; Hepatitis C, Chronic - drug therapy; Hepatitis C, Chronic - virology; Humans; Interferon-alpha - therapeutic use; Middle Aged; Molecular Sequence Data; Mutation; nonstructural (NS)5A protein; NS5A protein; Phylogeny; Protein Conformation; RNA, Viral - blood; secondary structure prediction; Transcription Factors - chemistry; Transcription Factors - genetics; Treatment Outcome; Viral Envelope Proteins - chemistry; Viral Envelope Proteins - genetics; Viral Nonstructural Proteins - chemistry; Viral Nonstructural Proteins - genetics; genetic diversity; nonstructural (NS)5A protein; hepatitis C virus; double-stranded RNA-activated protein kinase (PKR)-binding domain; secondary structure prediction; envelope (E)2 protein; double-stranded RNA-activated protein kinase (PKR)-eIF2α phosphorylation homology domain (PePHD); genetic complexity
• ISSN: 0042-6822; 1096-0341
• DOI: 10.1006/viro.2001.1092

Two regions within the HCV genome, hypervariable region 1 (HVR1) within the envelope (E)2 region and the PKR-binding domain (PKRbD) comprising the interferon sensitivity determining region (ISDR) within the nonstructural (NS)5A protein, have been reported to correlate with the outcome of antiviral treatment. Recently, a PKR/eIF2α phosphorylation homology domain (PePHD) within the E2 protein of HCV-1 isolates was described to inhibit PKR in vitro. PePHD deleted HCV-1 mutants remain capable of binding PKR to some extent while inhibition of PKR was found to be abolished by carboxy-terminal truncated E2 protein. The importance of mutations and quasispecies heterogeneity within the carboxy-terminal part of the E2 protein comprising the PePHD of HCV-1b is unknown. Therefore, the carboxy-terminal part of the HCV E2 gene (codons 618–746) including the PePHD was analyzed by sequencing of PCR products and individual clones of 41 HCV-1b-infected patients with sustained (SR, n = 12), end-of-treatment (ETR, n = 10), or no virological (NR, n = 19) response to antiviral therapy. Two highly conserved regions (codons 658–673 comprising the PePHD and codons 675–704) and one variable region (codons 705–720) were detected within the carboxy-terminal part of E2. No significant correlation of specific mutations or number of mutations with treatment response was observed for the PePHD and the carboxy-terminal part of the E2 protein. Phylogenetic and conformational analyses showed no specific clusters related to treatment outcome. Calculation of genetic complexity and diversity based on nucleotide sequence analyses of 20 individual clones per patient showed no differences between matched SR, ETR, and NR patients. However, calculation of genetic complexity and diversity on the basis of amino acid sequences showed significantly lower normalized Shannon entropy as well as mean Hamming distances for SR patients than in ETR and NR patients (P = 0.029 and P = 0.027, respectively). This indicates that patients achieving a sustained virological response to interferon-α-based antiviral therapy may elicit more effective immunological pressure, resulting in continuous clearing of individual variants of HCV quasispecies.