Comparison of ligase detection reaction and real-time PCR for detection of low abundant YMDD mutants in patients with chronic hepatitis B

AIM: To compare the ligase detection reaction (LDR) and real-time PCR for detection of low abundant YMDD mutants in patients with chronic hepatitis B infection.METHODS: Mixtures of plasmids and serum samples from 52 chronic hepatitis B patients with low abundant lamivudine-resistant mutations were tested with LDR and real-time PCR. Time required and reagent cost for both assays were evaluated.RESULTS: Real-time PCR detected 100, 50, 10, 1 and 0.1% of YIDD plasmid, whereas LDR detected 100, 50, 10, 1, 0.1, and 0.01% of YIDD plasmid, in mixtures with YMDD plasmid of 106 copies/mL. Among the 52 clinical serum samples, completely concordant results were obtained for all samples by both assays, and 39 YIDD, 9 YVDD, and 4 YIDD/YVDD were detected. Cost and time required for LDR and real-time PCR are 60/80 CNY (8/10.7 US dollars) and 4.5/2.5 h, respectively.CONCLUSION: LDR and real-time PCR are both sensitive and inexpensive methods for monitoring low abundant YMDD mutants during lamivudine therapy in patients with chronic hepatitis B. LDR is more sensitive and less expensive, while real-time PCR is more rapid.

Alanine aminotransferase is an inadequate surrogate marker for detecting lamivudine resistance

AIM: To investigate the accuracy of serum alanine aminotransferase (ALT) in diagnosing lamivudine resistance and factors that contributed to abnormal serum ALT.METHODS: This was a retrospective study of chronic hepatitis B patients on lamivudine therapy who were followed for 3-mo with liver function tests and hepatitis B virus (HBV) DNA measurement. Lamivudine resistance was defined as HBV DNA ≥ 1 log from nadir on at least 2 occasions, confirmed by genotyping. Serum ALT levels in patients with lamivudine resistance were compared to serum ALT levels in those without lamivudine resistance. RESULTS: There were 111 patients with and 117 without lamivudine resistance. The area under the receiver operating characteristic of serum ALT to diagnose lamivudine resistance was 0.645 ± 0.037. Serum ALT > 42.5 U/L gave the best diagnostic accuracy with sensitivity = 61%, specificity = 60%, positive predictive value = 60%, negative predictive value = 61%, positive likelihood ratio = 1.53 and negative likelihood ratio = 0.65 for predicting lamivudine resistance, missing 39% of resistant patients. Using other serum ALT cutoffs, diagnostic accuracy was lower. By multivariate analysis, baseline abnormal serum ALT was associated with abnormal ALT during resistance (OR = 5.98, P = 0.003), and males were associated with serum ALT flares during resistance (OR = 8.9, P = 0.016). CONCLUSION: Serum ALT is inadequate for diagnosing lamivudine resistance and has implications where viral resistance testing is suboptimal and for reimbursement of rescue therapy.

Outcome of lamivudine-resistant hepatitis B virus is generally benign except in cirrhotics

AIM： We set to determine factors that determine clinical severity after the development of resistance.METHODS： Thirty-five Asian patients with genotypic lamivudine resistance were analyzed in three groups： 13/35 （37%） were non-cirrhotics with normal pre-treatment ALT （Group IA）, 12/35 （34%） were non-cirrhotics with elevated pre-treatment ALT （Group IB）, and 10/35 （29%） were cirrhotics （Group II）. Patients were followed for a median of 98 wk （range 26-220） after the emergence of genotypic resistance.RESULTS： Group IA patients tended to retain normal ALT. Group IB patients showed initial improvement of ALT with lamivudine but 9/12 patients （75%） developed abnormal ALT subsequently. On follow-up however, this persisted in only 33%. Group II patients also showed improvement while on treatment, but they deteriorated with the emergence of resistance with 30% death from decompensated liver disease. Pretreatment ALT levels and CPT score （in the cirrhotic group） were predictive of clinical resistance and correlated with peak ALT levels and CPT score.CONCLUSION： The phenotype of lamivudine-resistant HBV correlated with the pretreatment phenotype. The clinical course was generally benign in non-cirrhotics. However, cirrhotics had a high risk of progression and death （30%） with the development of lamivudine resistance.

Character of HBV (hepatitis B virus) polymerase gene rtM204V/I and rtL180M mutation in patients with lamivudine resistance

Objectives: To investigate the relationship between HBV (hepatitis B virus) polymerase gene 180 and 204 sites mutation and lamivudine resistance. Methods: One hundred forty-one patients with lamivudine resistance after lamivudine treatment and 60 chronic hepatitis B patients without lamivudine treatment were enrolled in this study. The serum HBV DNA mutation was analyzed by sequence detection via polymerase chain reaction (PCR). The sequences of the same patient were analyzed before and after lamivudine treatment. Results: One hundred and nine lamivudine resistance patients had HBV YMDD (tyrosine-methionine-aspartate-aspartate) mutation. Among them, 45 patients had rtL 180M/M204V mutation (41.28%), 28patients had rtL180M/M204I mutation (25.70%) and 36 patients had rtM204I mutation (33.02%). There were 6 patients with rtL180M mutation in 32 lamivudine resistance patients. Sixty chronic hepatitis patients without lamivudine treatment had no mutations. Conclusions: HBV mutations, which play an important role in lamivudine resistance usually locate at polymerase gene 204 site; 180 site mutation was also observed in these patients. Evaluation of the anti-virus therapy by surveillance of the two sites mutations is of importance.

Prophylaxis of hepatitis B recurrence in post-liver transplantation patients with lamivudine-resistant YMDD mutant

Background The most frequently used therapy for post-transplantation recurrence of hepatitis B virus （HBV） infection is lamivudine, but this drug is associated with a high resistance rate due to YMDD mutant. In preliminary reports, adefovir dipivoxil （ADV） has been shown to have activity against lamivudine-resistant strains of HBV. However, clinical experience in treatment of HBV infection after liver transplantation （LT） is still not entirely clear. This study was aimed to evaluate the prophylactic efficacy of ADV plus hepatitis B immunoglobulin （HBIG） in patients with YMDD mutant before LT. Methods From March 2004 to March 2006, 16 patients with chronic hepatitis B had lamivudine-resistant YMDD mutants detected prior to liver transplantation and received treatment with ADV plus additional intramuscular HBIG after LT as prophylaxis against graft reinfection. Tests for liver function, serum HBsAg, anti-HBs （HBIG）, HBeAg, anti-HBc, anti-HBe, HBV-DNA, and creatinine were assessed pre- or post-liver transplantation. Results The median follow-up of these patients post-liver transplantation was 19.4 months. Fifteen patients survived and one patient died of recurrence of hepatocellular carcinoma （HCC）. There was significant difference （10.98% vs. 2.26%, P〈0.05） in YMDD mutant rate between the patients with HBV-DNA over 106 copies/ml and those with HBV-DNA less than 106 copies/mi. Fifteen patients （93.8%） had undetectable HBV-DNA at 4 weeks and 1 （6.3%） at 6 months after LT. No hepatitis B recurrence was detected by persistent testing of HBsAg, HBeAg, and HBV-DNA and no increase of serum creatinine level associated with ADV was observed in any of the patients. Conclusion ADV combined with intramuscular HBIG can effectively prevent patients with pre-transplantation YMDD mutant from HBV recurrence after LT.