title: Genotype-specific mutations in the polymerase gene of hepatitis B virus potentially associated with resistance to oral antiviral therapy.
abstract: The evolution of hepatitis B virus (HBV) and the role of different variants during antiviral therapy may be influenced by HBV genotype. We have therefore analysed substitutions potentially related to nucleos(t)ide analogues (NAs) resistance at 42 positions within RT-region in a cohort of patients with chronic hepatitis B in relation to HBV-genotype. RT mutations analysis was performed by direct sequencing in 200 NAs-naïve patients and in 64 LAM or LAM+ADV experienced patients with NAs resistance, infected mainly by HBV-genotypes D and A. 27 polymorphic-sites were identified among the 42 positions analysed and 64 novel mutations were detected in 23 positions. Genotype-D displayed the highest mutation frequency (6.4%) among all HBV-genotypes analysed. Single or multiple mutations were detected in 80% of naïve patients. Overall, the most frequent single mutations were at residues rt54, rt53 and rt91 which may associate with significantly lower HBV-DNA levels (p=0.001). Comparison with sequencing data of patients failing LMV or LAM+ADV therapy revealed an higher frequency of novel genotype-specific mutations if compared with naïve patients: 3 mutations under LAM monotherapy in HBV-D (rtS85F; rtL91I; rtC256G) and 3 mutations under ADV therapy in HBV-A (rtI53V; rtW153R; rtF221Y). In HBV-D treated patients the dominant resistance mutation was rtL80V (31.4%) and rtM204I (60%) in LAM+ADV group while LAM-treated patients showed a preference of rtM204V (51.9%). Interestingly, none of HBV-A patients had mutation rtM204I under ADV add-on treatment but all of them had the "V" AA substitution. These results suggested that in patients with CHB, HBV-genotype might be relevant in the evolution and development of drug resistance showing also different mutation patterns in the YMDD motif between HBV genotype D and A.
authors.affiliation: Venetian Institute of Molecular Medicine, Padova, Italy. s.mirandola@libero.it
authors.forename: Silvia
authors.initials: S
authors.lastname: Mirandola
authors.forename: Giada
authors.initials: G
authors.lastname: Sebastiani
authors.forename: Cristina
authors.initials: C
authors.lastname: Rossi
authors.forename: Emanuela
authors.initials: E
authors.lastname: Velo
authors.forename: Elke Maria
authors.initials: EM
authors.lastname: Erne
authors.forename: Alessandro
authors.initials: A
authors.lastname: Vario
authors.forename: Diego
authors.initials: D
authors.lastname: Tempesta
authors.forename: Chiara
authors.initials: C
authors.lastname: Romualdi
authors.forename: Davide
authors.initials: D
authors.lastname: Campagnolo
authors.forename: Alfredo
authors.initials: A
authors.lastname: Alberti
mesh_terms: D000225:Adenine / Q000031:analogs & derivatives / Q000494:pharmacology; D000284:Administration, Oral; D019943:Amino Acid Substitution; D000998:Antiviral Agents / Q000494:pharmacology*; D004279:DNA, Viral / Q000235:genetics; D024882:Drug Resistance, Viral / Q000235:genetics*; D004359:Drug Therapy, Combination; D015751:Genes, pol; D005838:Genotype; D006147:Guanine / Q000031:analogs & derivatives / Q000494:pharmacology; D006515:Hepatitis B virus / Q000145:classification / Q000201:enzymology / Q000235:genetics* / Q000472:pathogenicity; D019694:Hepatitis B, Chronic / Q000188:drug therapy / Q000821:virology; D006801:Humans; D019259:Lamivudine / Q000494:pharmacology; D009154:Mutation; D059645:Mutation Rate; D063065:Organophosphonates / Q000494:pharmacology; D015995:Prevalence; D014779:Virus Replication
chemical_list: D000998:Antiviral Agents; D004279:DNA, Viral; D063065:Organophosphonates; D019259:Lamivudine; C413685:entecavir; D006147:Guanine; D000225:Adenine; C106812:adefovir dipivoxil