Correlation of the occurrence of YMDD mutations with HBV genotypes,HBV-DNA levels,and HBeAg status in Chinese patients with chronic hepatitis B during lamivudine treatment

BACKGROUND:Continuous lamivudine therapy is associated with high rates of YMDD mutations,which are the main causes of drug resistance.The current study explores the association of the emergence of YMDD mutations with pretherapy HBV genotype,HBV-DNA levels,HBeAg status,and serum alanine aminotransferase(ALT) levels in Chinese patients receiving lamivudine therapy for chronic hepatitis B.METHODS:A total of 319 chronic hepatitis B patients who received lamivudine therapy for more than a year were enrolled in this study.YMDD mutations,HBV genotype,HBV-DNA levels,HBeAg status,and ALT levels were determined prior to their lamivudine treatment and every three months for a year of this therapy.RESULTS:Among the 319 patients,137(42.95%) were infected with genotype B and 182(57.05%) with genotype C.Up to 94 patients(29.47%) developed YMDD mutations within one year of lamivudine therapy.Furthermore,50 patients with HBV genotype B and 44 patients with genotype C developed YMDD mutations(36.50% vs 24.18%,P<0.05).Logistic regression analysis showed that pretherapy HBV genotype,HBV-DNA levels,and HBeAg status are independent factors for the emergence of YMDD mutations(HBV genotype:OR=2.159,95% CI 1.291-3.609,P=0.003;HBV-DNA:OR=1.653,95% CI 1.231-2.218,P=0.001;HBeAg:OR=2.021,95% CI 1.201-3.399,P=0.008).CONCLUSIONS:HBV genotype,HBV-DNA levels,and HBeAg status at baseline are the independent factors associated with the emergence of YMDD mutations among Chinese patients receiving lamivudine therapy for chronic hepatitis B.These findings are helpful to the development of therapeutic strategies for these patients.

Clinical features of chronic hepatitis B patients with YMDD mutation after lamivudine therapy

Objective: To study the clinical features of chronic hepatitis B (CHB) patients with tyrosine-methionine-aspartateaspartate (YMDD) mutation after lamivudine therapy. Methods: This investigation was a retrospective study of 63 CHB patients with YMDD mutation during lamivudine therapy. Clinical data, including period and types of YMDD mutation; hepatitis B virus (HBV) DNA levels and alanine aminotransferase (ALT) levels before and after YMDD mutation were measured. YMDD mutation in the HBV DNA polymerase gene was determined using polymerase chain reaction (PCR) and direct sequencing. HBV DNA quantification was determined using real-time PCR. Relevant serum markers of HBV were measured. The follow-up period was 12 months after YMDD mutation. Results: YMDD mutation occurred 7～44 months (median, 21.5 months) after the start of lamivudine therapy. The majority of the cases (42/63, 66.6%) had YMDD mutants detected between 12 and 24 months. Four types of YMDD mutation were observed in this study, rtL180M/M204V mutation was the predominant type (26/63, 41.3%). A proportion of patients (16/63, 25.4%; 12/63, 19.1%) had higher HBV DNA levels and ALT levels (after mutation vs before mutation),respectively. Conclusion: The majority of patients with YMDD mutants had similar or lower HBV DNA levels and ALT levels compared with baseline values. This subset of patients might have benefited from the continued lamivudine therapy. The patients with increased ALT and HBV DNA levels (breakthrough hepatitis) should benefit from the addition of a newer nucleotide analogue (e.g. adefovir).

Rapid re-emergence of YMDD mutation of hepatitis B virus with hepatic decompensation after lamivudine retreatment

Lamivudine has a high rate of antiviral resistance. Sequential treatment of anti-hepatitis B virus (HBV) is commonly used for lamivudine resistance. We report 4 cases of patients with rapid redetection of HBV mutants during the lamivudine retreatment. The four patients received lamivudine as an initial treatment of HBV and adefovir and lamivudine as a rescue therapy consecutively. HBV-DNA level, YMDD mutations and adefovir -resistant mutations (RFMP) were tested every 3 mo during the sequential treatment. All the patients showed YMDD mutations during the initial lamivudine therapy. After adefovir therapy for lamivudine resistance, they showed viral breakthrough. Adefovir was switched to lamivudine, however, it did not induce viral suppression at all, rather increased HBV-DNA with rapid reemergence of the YMDD mutations. All the patients had ALT flares, and hepatic decompensation occurred in two patients. After switching to adefovir combined with entecavir or lamivudine for a rescue therapy, the patients had reduction in HBV-DNA and ALT improvement. These cases demonstrated that lamivudine retreatment of patients with preexposed lamivudine resistance leads to rapid reemergence of YMDD mutation with significant viral rebounds and subsequent hepatic decompensation. Sequential administration of lamivudine in patients with a prior history of YMDD mutation should be abandoned.

Relationship between hepatocellular carcinoma and hepatitis B virus genotype with spontaneous YMDD mutations

AIM: To investigate the relationship between hepatitis B virus (HBV) genotype with spontaneous YMDD mu-tations and hepatocellular carcinoma (HCC) in HBV-related cirrhosis. METHODS: We investigated 264 liver cirrhosis pa-tients who were not treated with antiviral drugs, in-cluding 81 patients with HCC. YMDD mutations were detected by fluorescent hybridization bioprobe poly-merase chain reaction (PCR) and melting curve assay using the Diagnosis Kit for HBV YMDD Mutation. Serum HBV genotypes were detected by real-time PCR using genotype-specific TaqMan probes. Statistical analysis was performed according to data type using the t test, χ2 test and unconditional logistic regression analysis. RESULTS: In the HCC group, genotype C strains, spon-taneous YMDD mutations, and genotype C strains with YMDD mutations were detected in 33 (40.74%), 13 (16.05%) and 11 (13.58%) patients, respectively. In the liver cirrhosis (LC) group, HBV genotype C strains,spontaneous YMDD mutations, and genotype C strains with YMDD mutations were detected in 33 (18.03%), 7 (3.83%) and 2 (1.09%) patients, respectively. The dif-ferences in genotype C strains, spontaneous YMDD mu-tations, and genotype C strains with YMDD mutations between the two groups were statistically significant (χ2=15.441, P=0.000; χ2=11.983, P=0.001; P=0.000). In the HCC and LC groups, there were seven patients infected by genotype B strains with YMDD mutations and 13 by genotype C strains with YMDD mutations. Further research revealed that HCC oc-curred in 2 patients infected by genotype B strains with YMDD mutations and 11 infected by genotype C strains with YMDD mutations. The difference was statistically significant (P=0.000). Unconditional logistic regres-sion analysis revealed that patients infected by geno-type C strains with spontaneous YMDD mutations had a 7.775-fold higher risk for the development of HBV-related HCC than patients infected by other type HBV strains (P=0.013, 95%CI: 1.540-39.264). CONCLUSION: Genotype C strains with spontaneous YMDD mutations are an independent risk factor for HCC in LC patients and are important for early warning of HCC.

Hepatitis B virus genotypes and lamivudine resistance mutations in Jordan

AIM:To investigate and identify prevalent hepatitis B virus(HBV) genotypes and to explore lamivudine-resistant mutations among treated and untreated patients in Jordan.METHODS:A total of 107 cases with chronic hepatitis B were recruited from different medical centers in Jordan.Serological tests were preformed for all cases using a microparticle enzyme immunoassay.HBV Genotyping was performed for 70 cases using Line probe genotyping assay.The YMDD mutations were explored for 20 cases(4 were lamivudine naive) using the INNO-LiPA HBV DR assay.RESULTS:Genotype D was the only detected genotype.A total of 6 YMDD mutations were detected in 5 treated patients(31%) while one mutation was detected in the naive patients.Seventeen percent of cases were positive for HBeAg and had statistically significant higher levels of serum aminotransferases.CONCLUSION:HBV genotype D appears to be the only circulating type in Jordanian patients.The YMDD mutations were detected in 31% of lamivudine-treated cases with similar patterns to those found in the literature.We also found a relatively low prevalence of HBeAg expression among examined cases(17%).Awareness of these serologic,genotypic and resistance patterns might help in the formulation of management plans and for predicting clinical outcomes.Further larger scale studies are needed to confirm our results and to examine possible associations among clinical,serologic,and genetic patterns of HBV infections in Jordan.

YMDD mutations in patients with chronic hepatitis B untreated with antiviral medicines

AIM: To polymerase P region (YMDD) mutations of hepatitis B virus gene (HBV DNA) in patients with chronic hepatitis B (CHB) untreated with antiviral medicines and to explore its correlation with pre-c-zone mutations, HBV genotypes and HBV DNA level, and to observe its curative effect.METHODS: A total of 104 cases (38 cases in group of familial aggregation and 66 cases in group of non-familial aggregation) were randomly chosen from 226 patients with CHB who did not receive the treatment of lamivudine (LAM)and any other antivirus drugs within the last one year.Their serum YMDD mutations were detected by microcosmic nucleic acid and cross-nucleic acid quantitative determination,HBV genotypes by PCR-microcosmic nucleic acid crossELISA, HBV DNA quantitative determination and fluorescence ration PCR analysis, hepatitis B virus markers (HBVM) by ELISA. LAM was taken by 10 patients with YMDD mutations and its curative effect was observed.RESULTS: Twenty-eight cases (26.9%) had YMDD mutations, of them 11 cases (28.9%) were in familial aggregation group (38 cases) and 17 cases (25.8%) in nonfamilial aggregation group (66 cases) with no significant difference between the two groups. Twenty-seven point one percent (16/59) cases were positive for HBeAg YMDD mutations, and 26.7% (12/45) cases were negative for HBeAg and positive for anti-HBe. There was also no significant difference between the two groups. Different YMDD incidence rate existed in different HBV genotypes.HBV DNA level did not have a positive correlation with the incidence of YMDD mutations. LAM was effective for all patients with mutations.CONCLUSION: Wild mutant strains in HBV and their incidence rate have no significant difference between familial aggregation and non-familial aggregation. It may have no significant relationship between YMDD mutations and pre-c-zone mutations. HBV DNA level may not have a positive correlation with YMDD mutations. LAM is clinically effective for CHB patients with YMDD mutations.

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.

PCR restriction fragment length polymorphism in detection of YMDD variants of viral polymerase in hepatitis B virus patients treated with lamivudine

Objective: To analyse the emergence of YMDD motif(tyrosine-methionine-aspartate-aspartate) variants inpatients with hepatitis B treated with lamivudine.Methods: The amino acid substitution from methio-nine or isoleucine at the YMDD motif at the HBVpolymerase gene is a main mutation resistant to lami-vudine treatment. Generated from a fragment of do-main C of the polymerase gene, patients HBV DNA,which had been positive previously became positive a-gain ever since it had been negative during lamivudi-ne therapy. Variants were detected by cleavage of theproducts of the three PCRs with following enzymes:FokI, SspI, Alw441. The results of PCR-RELP wereanalysed by 8. 4% polypropylene acidemide gel elec-trophoresis. PCR-RFLP assay was compared to di-rect sequencing.Results: HBV DNA was positive again in 33 patientsand positive for one year in 2 patients. YMDD vari-ants were detected in serum 14 of 35 patients, YIDDvariants in 4, YVDD variants in 6, and YI/MDD va-riants in 1; all were in concordance with the resultsof direct sequencing. The samples of other 3 patientsshowed YI/VDD mutations, as shown by direct se-quencing. The results of PCR-RFLP assay of themixed sera of YIDD and YVDD variants were similarto those sera of YI/VDD variants.Conclusion: PCR-RFLP is suitable for rapid detec-tion of YMDD variants of viral polymerase in hepati-tis B virus patients treated with lamivudine.

Lamivudine resistance mutations in patients infected with hepatitis B virus genotype D

AIM: To determine the distribution of viral genotypes for primary or acquired lamivudine resistance. METHODS: A total of 283 patients with chronic hepatitis B virus (HBV) infection (245 patients with chronic hepatitis B and 38 inactive hepatitis B surface antigen carriers) were included in the study. The HBV geno-type was determined by using quantitative real-time polymerase chain reaction and sequence analysis, and tyrosine-methionine-aspartate-aspartate (YMDD) motif mutations were determined using the reverse transcriptase hybridization method. RESULTS: Lamivudine resistance was determined in a total of 25 (10.7%) chronic hepatitis B patients. Eight subjects (4%) had primary resistance to lamivudine, and 17 (53.1%) had secondary resistance to lamivudine. Genotype D, which was isolated from 267 of the patients with chronic HBV infection, was the dominant genotype in Turkey. CONCLUSION: Identification of YMDD motif mutations should have a positive impact on the selection of proper antiviral medication for patients, even for those who are nucleoside nave.

Clonal evolution of hepatitis B virus polymerase gene mutations during lamivudine-adefovir combination treatment

AIM:To identify hepatitis B virus polymerase gene mutations during antiviral therapy using lamivudineadefovir sequential monotherapy followed by lamivudine-adefovir combination therapy.METHODS:The patient cohort included four adult chronic hepatitis B patients who had undergone sequential monotherapy,first with lamivudine(LMV) and then,after developing viral breakthrough,with adefovir(ADV) therapy.All of the patients had non-response or viral breakthrough after LMV-ADV sequential monotherapy,which resulted in the switching of their antiviral regimen to LMV-ADV combination therapy.Eleven serum samples from the four patients who showed non-response to rescue LMV-ADV combination therapy were collected sequentially at a time before the antiviral treatment and then during the LMV monotherapy,ADV monotherapy,and LMV-ADV combination therapy.For the genotypic analysis,the whole 1310-bp polymerase gene region was amplified,cloned and sequenced.RESULTS:All patients had been previously treated with 100 mg of LMV once daily for a 15-to 26-mo period.The emergence of resistance mutations to LMV,such as rtM204V/I and/or rtL180M,were found in all patients.Their antiviral regimens were switched to ADV monotherapy as the second line treatment.All patients had viral breakthrough or non-response after the LMV-ADV sequential monotherapy.ADV-resistant mutations were detected after 13 to 19 mo of LMV-ADV sequential monotherapy.The rtA181V/T mutations were predominantly identified during the ADV treatment in the LMV-resistant patients.Twenty-seven of 38 clones were combined with an amino acid change at rt181;three clones had mutations in rt236 and one clone had a combined mutation.The rtA181V/T mutations were not suppressed by the LMV-ADV combination therapy.Thirty-nine of 64 clones showed an rtA181V/T mutation and six clones showed combined mutations in rt181 and rt236.Mutations in rt204 re-emerged during the combination treatment.The rt181 and rt204 mutations did not co-exist in one clone.CONCLUSION:Add-on lamivudine therapy with adefovir for adefovir resistance may not suppress the pre-existing adefovir-resistant mutation that develops during lamivudine-adefovir sequential monotherapy.

EFFECTS OF MUTATIONS IN THE POLYMERASE GENE OF HEPATITIS B VIRUS GENOME ON LAMIVUDINETHERAPY

Objective To explore the offects of mutations in tyrosine-methionine-aspartic acid-aspartic acid (YMDD) motif of the polymerase in the hepatitis B virus (HBV) genome on lamivudine antiviral therapy. Methods Partial HBV DNA segment containing the YMDD motif in the P gene wes obtained through amplifi- cation by polymerase chain reaction (PCR )from 19 chronic hepatitis B patients with serum HBV DNA positive at the 48th week treatment with lamivudine and subjected to automatic sequencing. Influences of vartants with YMDD mutations on lamivudine therapy were seen by observing the dynamic changes of serum HBV DNA and ALT levels. Results Serum HBV DNA breakthrough was found in 3 out of 10 individuals with detection of the YMDD mutations at the 48th week and in 5 at the 52th week, 2 of the 5 patients accompanied by serum ALT re-elevation, whereas of 9 subjects without YMDD mutations, 2 experenced an HBV DNA breakthrough at the 48th week and 1 of them had a conversion from HBV DNA positive DNA positive to negative at the 52th week. Patients with detectable HBV DNA level had a fluctuating level of serum ALT all time during the treatment. Conclusion Detection of mutations in the YMDD motif of polymerase gene in HBV genome during the lamivudine therapy will be helpful to monitoring its therapeutic outcomes.

Lamivudine resistance in children with chronic hepatitis B

Currently, although lamivudine(LAM) has a low genetic barrier, only interferon-alpha and LAM are available as a first-line treatment in children with chronic hepatitis B(CHB). LAM is a potent inhibitor of hepatitis B virusdeoxyribonucleic acid(HBV-DNA) polymerase replication by termination of the proviral HBV-DNA chain. LAM has a good safety and tolerability profile in CHB patients with hepatic decompensation. However, the main disadvantages of this HBV reverse transcriptase inhibitor are:(1) pre-existing covalently closed circular DNA cannot be eradicated by LAM, thus relapse after therapy withdrawal is frequent; and(2) although the longer LAMtreatment induced the higher seroconversion rate, the risk of viral resistance increased through the selection of YMDD(tyrosine, methionine, aspartate, aspartate) motif. Insufficient suppression of viral replication leads to the emergence of resistant strains that could result in virological breakthrough which is usually followed by biochemical breakthrough. Mutant strains affects additional resistance and cross resistance, leading to drug resistance in a significant number of CHB patients. In this case, efficacy of more powerful anti-viral agents with higher genetic barrier against development of resistance is diminished. Furthermore, strains that are resistant to LAM could bring about vaccine escape mutants, decreasing the efficacy of HBV vaccine. A more potent drug with a high genetic barrier to resistance needs to be approved as the first-line treatment option for CHB in children.

Treatment of chronic hepatitis B patients with tyrosinemethionine-aspartate-aspartate mutations

Lamivudine is an antiviral used for the treatment of chronic hepatitis B. Several studies have reported various mutations that are induced by lamivudine therapy. These mutations in the tyrosine-methionineaspartate-aspartate(YMDD) motif are necessary and sufficient to confer high-level lamivudine resistance. During treatment with lamivudine, mutations develop in the YMDD motif of the hepatitis B virus(HBV) polymerase gene and lamivudine cannot prevent the replication of the mutant form. The virulence strain of developed mutation in the polymerase gene is lower than the original virus and they are susceptible to treatment with some other nucleoside analogs except lamivudine. Entecavir and tenofovir are potent HBV inhibitors and they can be confidently used as first line monotherapies. We read the article written by Tan et al that lamivudine therapy improved the clinical course in HBV patients with natural YMDD mutations. We think that lamivudine use for this patient group is not appropriate. These patients should use YMDD mutant form-effective drugs such as adefovir, tenofovir.

The relationship between HBV lamivudine resistance and HBV genotypes or basic core promoter mutations

OBJECTIVE: To investigate the relationship between HBV Iamivudine resistance and HBV genotypes or basic core promoter (BCP) mutations. METHODS: The common coated probes were synthesized according to the conserved regions of the preC gene of hepatitis B virus (HBV). Different colorized probes were chosen from the sequences of different genotypes of HBV (A to F), BCP and YMDD wild types and mutants, respectively. HBV DNA levels, HBV genotypes, BCP and YMDD resistants were analyzed by PCR microplate hybridization ELISA at the zero and 6th month after the patients were treated with lamivudine. RESULTS: HBV genotyping results showed that HBV types B, C, D accounted for about 30%, 36% and 23% patients respectively. Thirteen BCP mutations (type B in 1 patient, type C in 8 and type D in 4) were found before treatment with lamivudine. HBV DNA levels were lower than 100 pg/ml in 2 patients anti higher than 100 pg/ml in 11. 9.4% of the HBV patients (5/43; type C in 3 and type D in 2) showed YMDD resistants and 4 BCP mutations at the same time. CONCLUSION: Oral treatment of lamivudine decreases the level of serum HBV DNA. The appearance of HBV YMDD resistants is related to certain HBV genotypes, and most of them are BCP mutations.

Two-year Observation of the Clinical Efficacy in Treating Chronic Hepatitis B Patients with Ganxian Recipe (肝纤方) and Lamivudine

Objective: To evaluate the clinical efficacy of Ganxian recipe (肝纤方, GXR) and lamivudine (LVD) in a two-year treatment of chronic hepatitis B (CHB). Methods: One hundred and twenty patients with CHB were randomly divided into the combinedly treated group (combined group) of 40 CHB patients who were treated with GXR combined with LVD. Another 40 CHB patients were treated with LVD alone (WM group), and still another 40 CHB patients were treated with GXR alone (TCM group). All these cases were randomly controlled and observed for two years. Results: Comprehensive efficacy: Total effective rate of the combined group (complete response and partial response) was 92.5%, while that of the WM group was 67.5% and TCM group 57.5%, respectively, with the difference between them was significant ( P <0.01); after treatment, the hepatic functions (AST, ALT, SB) of the three groups were all reduced, and the reduction in the combined group was particularly significant in comparison with the WM group or TCM group, P <0.05 or P < 0.01 respectively, suggesting that the effect in the combined group was better than that in the other two groups; the rate of tyrosine-methionine-aspartate-aspartate (YMDD) virus mutation: it was 7.5% in the combined group, 40.0% in the WM group, and 5.0% in the TCM group; liver fibrosis improvement parameter: after treatment, the results in the combined group got better than those in the other two groups. Conclusion: GXR could inhibit the appearance of YMDD after long-term application of LVD, and combined use has marked synergism.

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.

拉米夫定耐药与HBV YMDD变异关系的研究

探讨拉米夫定耐药与HBVYMDD变异之间关系。对拉米夫定治疗的慢性乙型肝炎进行肝功能、乙肝病毒血清学指标、YMDD耐药基因变异检测。 10 2例慢性乙型肝炎血清中 ,HBVDNA阴性 6 3例 (6 1 8% ) ,39例阳性 ,其中HBVYMDD变异 2 2例 ,变异率为 5 6 4 % ,并与用药时间长短有关 ,9- 17个月和 18- 30个月变异检出率分别为5 1 7%和 70 % ,HBVYMDD变异组ALT为 (5 9 94± 8 6 0 )U/L ,显著高于无HBVYMDD变异组的 (5 0 6 0± 6 12 )U/L。基因芯片技术检测HBVYMDD变异有一定的临床意义 ,YMDD变异是HBV对拉米夫定耐药的原因之一。

HBVP基因YMDD变异的检测及临床应用的初步研究

目的采用错配PCR扩增方法进行HBVP基因YMDD变异的检测,对其临床意义进行初步的研究。方法应用分子克隆方法,构建YMDD、YVDD和YIDD变异的阳性质粒,并对该方法进行敏感性及特异性试验。对65例未经抗病毒治疗的乙型肝炎患者检测YMDD变异情况。结果经PCR方法、酶切鉴定及直接测序鉴定出YMDD、YVDD和YIDD质粒构建成功,且该方法具有较好的敏感性和特异性。65例未经拉米夫定治疗的乙型肝炎患者存在YMDD变异,出现变异6例,阳性率为9.07%;其中YIDD和YI/YMDD各1例,YVDD3例,YV/YMDD1例。结论本检测方法简便、实用,在未经抗病毒治疗的患者中可存在YMDD变异,其与野生株一样是自然存在的,抗病毒药物压力不是导致HBVYMDD变异的唯一因素。

慢性乙型肝炎患者HBV DNA YMDD变异的检测及意义

目的 了解慢性乙型肝炎患者HBVDNAYMDD变异的存在情况及意义。方法 检测 90例慢性乙型肝炎患者HBVDNAYMDD变异 ,对发生HBVDNAYMDD变异的 2 0例患者的肝功能、HBeAg、HBVDNA及HBVDNAYMDD变异情况进行分析。结果 90例慢性乙型肝炎患者中检出HBVDNAYMDD变异共 2 0例 (阳性率 12 0 0 % ) ,已服用拉米夫定者 3 6例 ,检出YMDD变异 9例 (2 5 0 0 % ) ,未服用拉米夫定患者 5 4例 ,检出YMDD变异 11例 (阳性率 2 0 3 7% )。在 2 0例YMDD变异患者中有 5例HBeAg阴性 ;2 0例YMDD变异患者HBVDNA在 3 0 2 1× 10 5～ 2 3 69× 10 8(5 41× 10 7± 7 75× 10 7)copies/ml ,ALT 3 4～ 12 16(2 88 2 0± 3 3 8 0 7)IU/L ,TB 8 9～ 3 2 6 7(4 8 74± 72 2 0 ) μmol/L。 结论 YMDD变异株可在拉米夫定治疗过程中出现 ,也可天然存在 ,YMDD变异可与前C基因变异同时存在 ,提示HBV的变异常常是多位点的 ;YMDD变异株HBV复制处于中～高度水平 ;YMDD变异株的致病性轻重不等 ,肝功能可为正常 ,也可是轻度～高度等不同程度异常。

阿德福韦酯联合拉米夫定治疗HBV-YMDD变异的研究

目的比较阿德福韦酯联合拉米夫定和单用阿德福韦酯治疗YMDD变异的慢性乙型肝炎的疗效和安全性。方法将112例在拉米夫定治疗过程中出现YMDD变异的慢性乙型肝炎患者随机分为两组(各56例),治疗组:继续接受拉米夫定100mg·d-1治疗,全程联合阿德福韦酯10 mg·d-1;对照组:拉米夫定100 mg·d-1和阿德福韦酯10 mg·d-1联合治疗12周后单用阿德福韦酯10 mg·d-1,疗程96周。结果两组患者治疗后ALT、AST水平均较治疗前显著改善(P<0.05);治疗组治疗48周,96周时肝功能ALT、AST改善优于对照组(P<0.05);HBV DNA转阴率显著高于对照组(P<0.05)。结论阿德福韦酯对YMDD变异的慢性乙型肝炎患者有良好的疗效和安全性,联合拉米夫定临床疗效更显著。