engleski

Resistance analysis of pre-treatment NS3 and NS5A variants in HCV genotype 1a, 1b and 3a infected patients in Croatia

The use of direct acting antivirals (DAA) resulted in significant improvement in efficacy of HCV treatment in the last decade with the rates of sustained virologic response that exceed 95%. The presence of resistance associated substitutions (RAS), especially in NS3 and NS5A region, has been associated with impaired response to DAA. The aim of this study was to characterize the differences in the prevalence of baseline NS3 and NS5A variants in Croatian patients infected with HCV prior to DAA treatment and assess clinical and virological characteristics associated with resistance to NS3- and NS5A- inhibitors. Direct Sanger sequencing of the NS3 and NS5A region was performed in 300 consecutive DAA-naïve patients chronically infected with HCV prior to DAA treatment at the University Hospital for Infectious Diseases Zagreb in Croatia. Resistance associated substitutions were identified using the geno2pheno [hcv] algorithm v.3.4. Phylogenetic analysis was done in MEGA v.10.2.6 using the maximum likelihood method under 1000 bootstrap replicates. Demographic, clinical and laboratory data (gender, age, HCV genotype, fibrosis stage, HCV RNA level) were collected for all patients. The association between the presence of RAS and selected variables was analysed by the Mann- Whitney test for continuous data and Pearson’s chi squared test or Fisher’s exact test for categorical data using Statistica v.13.5. Statistical significance was defined as p < 0, 05. Among the 300 patients included in the analysis, 109 (36, 3%) were infected with genotype 1a, 80 with genotype 1b (26, 7%) and 111 with genotype 3a (37, 0%). Overall NS3 and NS5A RAS prevalence was 33, 0% (99/300) and 13, 7% (41/300) respectively, with NS3 RAS being particularly more common in genotype 1a (75/109, 68, 8%) compared with genotype 1b (21/80, 26, 3%) and genotype 3a (2/111, 1, 8%) (p < 0, 001). All genotype 1a sequences segregated in 2 clearly distinct clades with NS3 variants being notably more prevalent in clade I (54/68, 79, 4%) compared with clade II (21/41, 51, 2%) (p = 0, 003). Among NS3 RAS, Q80K was the most common overall (51/300, 17%) and found only in genotype 1a (51/109, 46, 8%), predominantly in clade I (50/51, 98, 0%). NS5A RAS were more frequent in both genotype 1a (17/109, 15, 6 %) and genotype 1b (17/80, 21, 3%) compared with genotype 3a (7/111, 6, 3 %) (p = 0, 007). The most common NS5A RAS across all genotypes were M28V in genotype 1a (11/109, 10, 1%), Y93H in genotype 1b (9/80, 11, 3%) and A62L in genotype 3a (4/111, 3, 6%). No statistically significant associations between the presence of NS3/NS5A RAS and patients’ gender, age, fibrosis stage or HCV RNA level were observed. Baseline NS3 and NS5A RAS were frequently detected in DAA-naïve patients infected with HCV genotype 1a and 1b. Especially high prevalence of NS3 RAS was observed in patients infected with clade I of genotype 1a. This highlights the importance of combination regimens with a high genetic barrier to resistance and different target sites as the new standard of care for HCV treatment in order to limit potential risk of therapy failure, particularly for difficult-to- treat patients.

Hepatitis C virus ; Resistance-associated substitutions ; Direct-acting antivirals ; Population-based sequencing

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