Baseline quasispecies selection and novel mutations contribute to emerging resistance-associated substitutions in hepatitis C virus after direct-acting antiviral treatment.

Resistance-associated substitutions (RASs) in hepatitis C virus (HCV) appear upon failure of treatment with direct-acting antivirals (DAAs). However, their origin has not been clarified in detail. Among 11 HCV genotype 1b patients who experienced virologic failure with asunaprevir (ASV)/daclatasvir (DCV), 10 had major NS5A L31M/V-Y93H variants after treatment. L31M/V-Y93H variants were detected as a minor clone before therapy in 6 patients and were the most closely related to the post-treatment variants by phylogenetic tree analysis in 4 patients. Next, to consider the involvement of a trace amount of pre-existing variants below the detection limit, we analysed human hepatocyte chimeric mice infected with DAA-naïve patient serum. L31V-Y93H variants emerged after treatment with ledipasvir (LDV)/GS-558093 (nucleotide NS5B inhibitor) and decreased under the detection limit, but these variants were dissimilar to the L31V-Y93H variants reappearing after ASV/DCV re-treatment. Finally, to develop an infection derived from a single HCV clone, we intrahepatically injected full-genome HCV RNA (engineered based on the wild-type genotype 1b sequence) into chimeric mice. A new Y93H mutation actually occurred in this model after LDV monotherapy failure. In conclusion, post-treatment RASs appear by 2 mechanisms: the selection of pre-existing substitutions among quasispecies and the generation of novel mutations during therapy.

Modified diagnostic criteria of drug-induced liver injury proposed by the international consensus meeting.

BACKGROUND/AIMS: The usefulness of the diagnostic criteria of the International Consensus Meeting (criteria A) has been previously reported. However, these criteria are not clinically adaptable in Japan where allergic reaction is one of the major etiologies of drug-induced liver injury and thus it was revised and reported in the Digestive Disease Week-Japan of 2002 as DDW-J criteria (criteria B). It remains controversial whether the revised criteria can exclude drugs not causing liver injury. METHODOLOGY: Two new diagnostic criteria (criteria C and D) were designed to supplement the DDW-J criteria. Usefulness and limitations of the four criteria were retrospectively examined using cases of drug-induced liver injury experienced in 8 hospitals. RESULTS: It was confirmed that the sensitivity of criteria B is excellent for diagnosis of drug-induced liver injury. However, diagnostic criteria B were found to be disadvantageous in relation to specificity, while diagnostic criteria D were disadvantageous in relation to sensitivity. Sensitivity of diagnostic criteria C was a little superior to that of diagnostic criteria A. CONCLUSIONS: On the basis, the significant sensitivity of criteria B was confirmed again, however, modification should be done for increasing specificity. Criteria C appear to be the best for their sensitivity and specificity.