Quasispecies evolution in NS5A region of hepatitis C virus genotype 1b during interferon or combined interferon-ribavirin therapy

AIM: To evaluate the implication of substitutions in the hepatitis C virus (HCV) non-structural 5A (NS5A) protein in the resistance of HCV during mono-interferon (IFN) or combined IFN-ribavirin (IFN-R) therapy. Although NS5A has been reported to interact with the HCV RNA- dependent RNA polymerase, NS5B, as well as with many cellular proteins, the function of NS5A in the life cycle of HCV remains unclear. METHODS: HCV quasispecies were studied by clon- ing and sequencing of sequential isolates from patients infected by HCV genotype 1b. Patients were treated by IFN-α2b for 3 mo followed by IFN-α2b alone or com- bined IFN-R therapy for 9 additional months. Patients were categorized intro two groups based on their re- sponse to the treatments: 7 with sustained virological re- sponse (SVR) (quasispecies = 150) and 3 non-respond- ers (NR) to IFN-R (quasispecies = 106). RESULTS: Prior to treatment, SVR patients displayed a lower complexity of quasispecies than NR patients. Most patients had a decrease in the complexity of quasispe- cies during therapy. Analysis of amino acids substitu- tions showed that the degree of the complexity of the interferon sensitivity-determining region (ISDR) and the V3 domain of NS5A protein was able to discriminate thetwo groups of patients. Moreover, SVR patients displayed more variability in the NS5A region than NR patients. CONCLUSION: These results suggest that detailed mo- lecular analysis of the NS5A region may be important for understanding its function in IFN response during HCV 1b infection.

Hepatitis C virus NS5A region mutation in chronic hepatitis C genotype 1 patients who are non-responders to two or more treatments and its relationship with response to a new treatment

To determine the number of mutations in the NS5A region of the hepatitis C virus (HCV) and its relationship to the response to antiviral therapy in patients with chronic hepatitis C genotype 1 who are non-responders to two or more treatments. METHODSSequences within HCV NS5A [PKR binding domain (PKRBD) and the interferon-sensitivity-determining region (ISDR)] were analysed via direct sequencing in a selected cohort of 72 patients, with a total of 201 treatments [interferon-alpha (IFN-α), n = 49; IFN-α + ribavirin (RBV), n = 75; pegylated (peg) IFN-α + RBV, n = 47; first-generation direct-acting antivirals (DAAs), n = 13; and second-generation DAAs, n = 17]. Of these, 48/201 achieved a sustained virological response (SVR) and 153/201 achieved no virological response (NVR). RESULTSFor both regions, treatments resulting in SVR were associated with more baseline mutations than were treatments resulting in NVR (SVR vs NVR; PKRBD: 5.82 ± 3 vs 4.86 ± 2 mutations, P = 0.045; ISDR: 2.65 ± 2 vs 1.51 ± 1.7 mutations, P = 0.005). A decrease or no change in the number of mutations over time between treatments in the PKRBD or ISDR, as shown by sequencing, was associated with patients who usually failed to respond to treatment (PKRBD, P = 0.02; ISDR, P = 0.001). Moreover, patients showing a post-treatment baseline viral load > 600000 IU/mL and increased ISDR mutations with respect to the previous treatment were 9.21 times more likely to achieve SVR (P = 0.001). CONCLUSIONThe obtained results show that among patients who have shown no response to two or more antiviral treatments, the likelihood of achieving SVR increases with the genetic variability in the ISDR region (≥ 2 mutations or number of substitutions from the HCV-J and HCV-1 prototype), especially when the viral load is greater than 600000 IU/mL.

A Region Holds Its Breath

Death of Ethiopian leader Meles Zenawi brings stability concerns in the Horn THERE＇s no doubt that Ethiopia＇s deceased prime Minister Meles Zenawi was a key cog in the stability, development and security in the Horn of Africa. His footprints, for the 21 years that he was

Selection and application of serotypical synthetic peptides derived from hepatitis C virus NS5A region

Background Numerous studies have reported a relationship between hepatitis C virus （HCV） genotype and the response to interferon therapy. Despite high sensitivity and specificity, genotyping methods can be performed only on HCV RNA positive samples. Serotyping might be a rapid and cost effective method for determining HCV genotypes, especially in patients with previously undetectable HCV RNA. In this study, an enzyme linked immunosorbent assay （ELISA） method for HCV serotyping with the genotype specific, synthetic peptides derived from HCV nonstructural 5a （NS5A） region was developed. Methods Based on 45 sequences, representing HCV genotypes 1-6 from Genebank, we synthesised 305 overlapping 30-mer peptides within NS5A region at positions 2182-2343 of HCV. All peptides for antigenic reactivity were tested by enzyme immunoassay with 69 human sera with antiHCV positive representing genotype 1-6. Forty hepatitis C patient sera were serotyped using serotype specific, synthetic peptides and genotyped by sequencing analysis. Results The correspondence of amino acids in HCV NS5A region with amino acids in positions 2182-2343 was very low among different genotype peptides. The highly conserved sequences were residues 2182-2211 （R1）, 2272-2301 （R7） and 2302-2331 （R9）： the highly variable 2212-2241 （R3） and 2257-2286 （R6）. Using 305 peptides, antigenic regions were located in R3, R7 and R9. Eighteen peptides from highly conserved region representing genotypes 1 to 6 showed broad immunoreactivity with sera containing antibody to all HCV genotypes. Immunoreactivity of the peptides from highly variable region was stronger with similar genotype sera. Twelve unique peptides showed highly, genotype specific, reactivity with types 1 and 3 sera. Type 2 genotype specific peptides had cross reaction with type 3 serum. No type 4, 5 or 6 specific peptides were selected. The serotyping results showed high agreement with sequencing analysis. Conclusions The major antigenic regions in HCV NS5A region were at 2212-2241（R3）, 2272-2301（R7） and 2302-2331（R9）. Eighteen peptides from highly conserved region show genotype independent, immunoreactivity, useful for antiHCV antibody test. Twelve peptides from highly variable region show genotype 1 and 3 dependent immunoreactivity, useful for determining HCV serotype, especially for patients with previously undetectable HCV RNA.