title: Impact of the rtI187V polymerase substitution of hepatitis B virus on viral replication and antiviral drug susceptibility.
abstract: A high prevalence of the rtI187V polymerase substitution of hepatitis B virus (HBV) was detected in nucleoside/nucleotide-analogue-naive and -treated chronic hepatitis B (CHB) patients. We aimed at assessing the replicative capacity and susceptibility to lamivudine (LAM) and adefovir (ADV) in vitro of HBV harbouring rtI187V alone or in conjunction with LAM- or ADV-resistant mutations. The reverse transcriptase region of HBV isolates was directly sequenced from a cohort of 300 CHB patients from China. Replication-competent HBV constructs containing rtI187V and combined with LAM-resistant (rtM204I, rtL180M/rtM204V) mutations were generated, and compared with WT, LAM-resistant single (rtM204I) or double (rtL180M/rtM204V) and ADV-resistant (rtN236T) clones. In a Chinese cohort of 300 CHB patients, 8.7 % (26/300) showed substitution of rtI187 with V. Of note, the rtI187V prevalence in HBV genotype B was significantly higher than that in HBV genotype C (95.2 vs 4.8 %). In vitro phenotypic assays showed that the viruses bearing the rtI187V substitution had impaired replication efficacy when compared with the WT and the virus carrying rtI187V combined with LAM-resistant single or double mutations showed even more significantly impaired replicative capacities. Furthermore, rtI187V HBV remained susceptible towards treatment with LAM or ADV in vitro whereas the combination of the rtI187V substitution with LAM-resistant mutations rendered HBV resistant to LAM but still sensitive to ADV. Our study revealed that the rtI187V substitution in the HBV polymerase frequently occurred in CHB patients, particularly those with HBV genotype B. However, the emergence of the rtI187V substitution significantly impaired viral replication but without affecting drug sensitivity in vitro.
authors.affiliation: Department of Microbiology and Immunology, Institutes of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai, PR China.
authors.forename: Jiyun
authors.initials: J
authors.lastname: Fan
authors.affiliation: Department of Microbiology and Immunology, Institutes of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai, PR China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Chinese National Human Genome Center, Shanghai, PR China.
authors.forename: Hui
authors.initials: H
authors.lastname: Xiong
authors.affiliation: Department of Microbiology and Immunology, Institutes of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai, PR China.
authors.forename: Xiaokui
authors.initials: X
authors.lastname: Guo
authors.affiliation: Department of Pharmacology, Yale University School of Medicine, New Haven, CT, USA.
authors.forename: Yung-Chi
authors.initials: YC
authors.lastname: Cheng
mesh_terms: D000225:Adenine / Q000031:analogs & derivatives / Q000494:pharmacology; D000293:Adolescent; D000328:Adult; D000368:Aged; D019943:Amino Acid Substitution; D000998:Antiviral Agents / Q000494:pharmacology; D002648:Child; D002681:China; D015331:Cohort Studies; D004261:DNA Replication / Q000235:genetics; D024882:Drug Resistance, Viral / Q000235:genetics; D005260:Female; D005814:Genes, Viral; D056945:Hep G2 Cells; D006515:Hepatitis B virus / Q000187:drug effects / Q000235:genetics* / Q000502:physiology*; D019694:Hepatitis B, Chronic / Q000188:drug therapy / Q000821:virology; D006801:Humans; D019259:Lamivudine / Q000494:pharmacology; D008297:Male; D008875:Middle Aged; D009154:Mutation; D063065:Organophosphonates / Q000494:pharmacology; D012194:RNA-Directed DNA Polymerase / Q000235:genetics*; D014779:Virus Replication / Q000235:genetics; D055815:Young Adult
chemical_list: D000998:Antiviral Agents; D063065:Organophosphonates; D019259:Lamivudine; C053001:adefovir; D012194:RNA-Directed DNA Polymerase; D000225:Adenine