Clinical Study On Anti-hepatitis B Virus Infection With Nucleos(t)ide Analogues And The Impact Of Drug-resistant Mutation On The Viral Antigenicity

Infection with hepatitis B virus (HBV) remains a global health problem. Ithas been confirmed that chronic HBV infection is closely associated with livercirrhosis and hepatocellular carcinoma. However, the progression can be delayedor blocked by effective antiviral therapy. The nucleos(t)ide analogues arerevolutionary agents for treatment of chronic hepatitis B. Nevertheless, due to theshort period of the application of nucleos(t)ide analogues in the anti-HBV field,reports on the comparison of the efficacy between different nucleos(t)ideanalogues are rare, and few large-sample studies on risk factors of genotypicresistance are published, and many diputes still exist in some special mutants intheir biological features and clinical significance.In China, four nucleos(t)ide analogues currently approved are lamivudine,adefovir, telbivudine and entecavir. In this paper, we aim to analyze the efficacy ofthe four agents, study the risk factors of viral mutations in the process of treatmentwith nucleos(t)ide analogues, compare different rescue strategies for drugresistance and explore the biological feature and clinical significance ofrtA181T/sW172*mutation. We hope that the results and conclusions in this studycan give valuable help to medical staff in rational medication of nucleos(t)ideanalogues and prediction and management of drug resistance.In Part1, we compared the one-year efficacy of lamivudine, adefovir,telbivudine and entecavir in nucleos(t)ide analogue-na ve HBV-infectedHBeAg-positive patients with the method of Meta analysis. We searched Pubmed(from1966to March,2011), Embase(from1966to March,2011), CBMdisk (from1978to March,2011), Wanfang Database (from1998to March,2011) and CNKI(from1994to March,2011). Of these databases, CBMdisk, Wanfang Database andCNKI provided literatures in Chinese.2018articles were identified in the search,and after a review,16studies were finally included. Data analysis was carried outwith the use of ReviewManager Software4.2and forest plots were drawn. Theoutcomes showed that, the efficacy of entecavir was better than lamivudine(P=0.001) and adefovir (P<0.00001) in the rate of undetermined serum HBV DNA,and that telbivudine was superior to lamivudine (P=0.02) and adefovir (P=0.02) inthe rate of HBeAg clearance with higher rate of anti-HBe seroconversion than entecavir (P=0.001). We arrived at the conclusions that telbivudine and entecavirwere superior to the other two nucleos(t)ide analogues, and telbivudine took greatadvantage in HBeAg clearance.In Part2, we evaluated the risk factors of mutations in the HBVreverse-transcriptase gene for828Chinese patients treated with nucleos(t)ideanalogues. Factors included gender, age, diagnosis, HBV genotype, HBeAg status,serum HBV DNA level, ALT level, AST level, total bilirubin level and differentnucleos(t)ide analogues. The univariate and multivariate analysis showed that, age,HBeAg status, serum HBV DNA level and treatment with lamivudine or adefovirmonotherapy (entecavir monotherapy as control) were correlated with mutations.In details, older age (OR=1.585, P<0.05), HBeAg negativity (OR=1.775, P<0.05),higher on-treatment serum HBV DNA level (OR=1.369, P<0.05) andmonotherapy of nucleos(t)ide analogues with lower genetic barrier to resistancewere associated with greater risks of mutations in the HBV reverse-transcriptasegene.In Part3, we studied the four different rescue strategies for lamivudineresistance, which were lamivudine switching to adefovir, lamivudine switching toentecavir, lamivudine plus adefovir and lamivudine switching to the combinationof adefovir and entecavir. The results showed that, during the rescue treatmentperiod, the incidences of drug-resistant mutations in the above four groups wererespectively23.67%(49/207)(median duration of18months),18%(9/50)(median duration of17months),6.94%(5/72)(median duration of23months) and0%(0/9)(median duration of18months)(P<0.05). The incidence of singlertA181V/T mutation was very high (34.69%,17/49) in patients switching toadefovir monotherapy. Based on the results, we suggested that lamivudine plusadefovir and lamivudine switching to the combination of adefovir and entecavirwere optimal for lamivudine resistance, whereas lamivudine switching to entecavirmonotherapy was not recommended because of high incidence of drug resistance.In Part4, we explored the effect of rtA181T/sW172*mutation in the RTgene and its overlapping S gene on the HBV surface antigen with the aim ofdetermining the biological features and clinical significance of the mutation. Theoutcome in vitro indicated that rtA181T/sW172*mutant could impair thesecretion of HBsAg compared to the wild strain in the transfected HepG2cellculture supernatant. However, we found no statistic significance between patientswith single rtA181T mutation and patients without any drug-resistant mutation inthe HBV RT gene in median serum HBsAg (the former3865.52Coi vs. the latter3442.58Coi, P=0.69) and anti-HBs levels (the former2IU/L vs. the latter2IU/L,P=0.35). Furthermore, by contrasting the serum HBsAg levels after viral mutation to that before viral mutation (mean difference2444.57Coi, P<0.05) andcomparing the serum anti-HBs levels in the same patients, we also found nochange in the serum HBsAg and anti-HBs levels. So, we came to the conclusionsthat the secretion of HBsAg by the wild HBV strains might compensate thedecrease of HBsAg caused by rtA181T/sW172*mutation and the mutation had noeffect on the antigenicity of HBsAg or the the estimation of the antiviral efficacybased on quantitative serum HBsAg.