Heterogeneities of HBV reverse transcriptase domain (RT) gene mutations related to nucleos(t)ide analogues resistance

Abstract

Objective To analyze the heterogeneities of hepatitis B virus (HBV) reverse transcriptase domain (RT) gene mutations related to nucleos(t)ide analogues (NAs) resistance. Methods Blood samples from 2 765 chronic hepatitis B patients with virological breakthrough or poor drug response treated in Ningbo No.2 Hospital and Ningbo Fourth Hospital from April 2011 to March 2018 were collected. According to the medication status, it was divided into LAM monotherapy group (n=603), LdT monotherapy group (n=147), ADV monotherapy group (n=68), ETV monotherapy group (n=10) and the sequential or combined drug resistance of NAs group (n=365). The resistance mutation sites and drug resistance patterns (pathways) of each group were analyzed. The SPSS 19.0 software was used to analyze the data. Results Among 2 765 serum samples, the NAs-related HBV-RT resistance mutations were detected in 1 193 cases with an overall mutation rate of 43.15%. The mutation rate of LAM monoclonal resistance group was 62.62% (603/963) with 19 mutation types, the most common single point mutation was rtM204I/V (40.30%, 243/603). The mutation rate of LdT monoclonal resistance group was 45.51% (147/323), and there were 3 mutation types, with the single point mutation rtM204I/V being the most common (59.86%, 88/147). The mutation rate of the ADV monoclonal resistance group was 17.80% (68/382), mainly rtA181T single point mutation (64.71%, 44/68). The mutation rate of the ETV monoclonal resistance group was 4.06% (10/246), and the single point mutation of rtT184A/G/S/I/L/F was the most common one (80.00%, 8/10). The mutation rate of the sequential or combination therapy group was 41.91% (365/871), among which the mutation rate of the LAM/LdT poor response or the resistance with the sequential ADV group was 63.39% (142/224), and the most single mutation point was rtA181V/T (35.21%, 50/142); the mutation rate of LAM/LdT poor response or drug-resistant with combined ADV group was 42.19% (54/128), and the most common mutation point was rtA181V/T (46.30%, 25/54) ; the mutation rate of LAM/LdT with poor response or resistance after sequential ETV 1.0 mg was 44.66% (117/262), and the most common mutation point was rtL180M+ M204I/V+ S202G/I (31.62%, 37/117); the LAM/LdT poor response or the drug-resistant ETV combined with ADV group had a mutation rate of 7.14% (5/70), all of which were multi-site mutations; the mutation rate of poor response to ADV or resistant with sequential ETV 0.5 mg group was 28.14% (47/167), all of which were multi-site mutations. Secondary (compensation) sites such as rtV173L, rtL180M, and rtV214A, and single-point mutations such as rtV207I/L/G, rtS213Tand rtN238T, which were not fully defined, were detected. The resistance patterns (pathways) of NAs monotherapy were relatively simple, and the resistance patterns (pathways) of NAs experienced patients (sequential or combined treatment group) were complex and diverse, and multiple resistance patterns (pathways) existed, along with NAs increasing in species. Non-first-line NAs-related resistance patterns (pathways) showed an overall downward trend sand ETV-related drug-resistant mutation showed an overall upward trend. Conclusion The NAs-related HBV resistance mutation sites (patterns) are complex and diverse, especially multi-site mutations, refractory drug resistance mutations, multidrug resistance mutations and cross-resistance mutations. Therefore, the optimization of antiviral treatment strategies and drug resistance management concepts need to be continuously updated. Key words: Hepatitis B virus; Nucleos(t)ide analogues; Drug resistance mutation; Reverse transcriptase resistance mutation; Gene sequencing