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 2765 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 2765 serum samples, the NAs-related HBV-RT resistance mutations were detected in 1193 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 .