Search Results (3)

Hepatitis C virus (HCV) genotype (GT)3 is associated with increased risk of steatosis, development of cirrhosis and hepatocellular carcinoma. Limited data are available regarding genetic variability and use of direct-acting antiviral agents in these patients. non-structural protein 5A (NS5A) and non-structural protein 5B (NS5B) sequencing was performed on 45 HCV GT3-infected Italian patients subsequently treated with sofosbuvir ± daclatasvir (SOF ± DCV). Novel GT3a polymorphisms were observed by Sanger sequencing in three NS5A (T79S, T107K, and T107S) and three NS5B (G166R, Q180K, and C274W) baseline sequences in patients who achieved sustained virological response (SVR). Baseline NS5A resistance-associated substitutions A30K and Y93H were detected in 9.5% of patients; one patient with A30K did not achieve SVR. Phylogenetic analyses of sequences showed no distinct clustering. Genetic heterogeneity of NS5A and NS5B was evaluated using ultra-deep pyrosequencing (UDPS) in samples longitudinally collected in patients not achieving SVR. Some novel NS5A and NS5B polymorphisms detected at baseline may not impact treatment outcome, as they were not enriched in post-failure samples. In contrast, the novel L31F NS5A variant emerged in one treatment failure, and I184T, G188D and N310S, located on the same NS5B haplotype, became predominant after failure. These findings suggest a potential impact of these novel substitutions on the treatment outcome; however, their significance requires further investigation. Full article

Hepatitis C virus (HCV) is classified into seven phylogenetically distinct genotypes, which are further subdivided into related subtypes. Accurate assignment of genotype/subtype is mandatory in the era of directly acting antivirals. Several molecular methods are available for HCV genotyping; however, a relevant number of samples with indeterminate, mixed, or unspecified subtype results, or even with misclassified genotypes, may occur. Using NS5B direct (DS) and ultra-deep pyrosequencing (UDPS), we have tested 43 samples, which resulted in genotype 1 unsubtyped (n = 17), mixed infection (n = 17), or indeterminate (n = 9) with the Abbott RealTime HCV Genotype II assay. Genotype 1 was confirmed in 14/17 samples (82%): eight resulted in subtype 1b, and five resulted in subtype 1a with both DS and UDPS, while one was classified as subtype 1e by DS and mixed infection (1e + 1a) by UDPS. Three of seventeen genotype 1 samples resulted in genotype 3h with both sequencing approaches. Only one mixed infection was confirmed by UDPS (4d + 1a), while in 88% of cases a single component of the mixture was detected (five genotype 1a, four genotype 1b, two genotype 3a, two genotype 4m, and two genotype 4d); 44% of indeterminate samples resulted genotype 2c by both DS and UDPS, 22% resulted genotype 3a; one indeterminate sample by Abbott resulted in genotype 4d, one resulted in genotype 6n, and one was classified as subtype 3a by DS, and resulted mixed infection (3a + 3h) by UDPS. The concordance between DS and UDPS was 94%, 88%, and 89% for genotype 1, co-infection, and indeterminate results, respectively. UDPS should be considered very useful to resolve ambiguous HCV genotyping results. Full article

DNA sequence analysis is undertaken in many biological research laboratories. The workflow consists of several steps involving the bioinformatic processing of biological data. We have developed a suite of web-based online bioinformatic tools to assist with processing, analysis and curation of DNA sequence data. Most of these tools are genome-agnostic, with two tools specifically designed for hepatitis B virus sequence data. Tools in the suite are able to process sequence data from Sanger sequencing, ultra-deep amplicon resequencing (pyrosequencing) and chromatograph (trace files), as appropriate. The tools are available online at no cost and are aimed at researchers without specialist technical computer knowledge.
The tools can be accessed at http://hvdr.bioinf.wits.ac.za/SmallGenomeTools, and the source code is available online at https://github.com/DrTrevorBell/SmallGenomeTools. Full article