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.

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).

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.

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.

Clinical characteristics and distribution of hepatitis B virus genotypes in Guangxi Zhuang population

AIM: To investigate the distribution of HBV genotypes and their YMDD mutations in Guangxi Zhuang population, China, and to study the relationship between HBV genotypes and clinical types of HB, ALT, HBV DNA, HBe system as well as the curative effect of Lamivudine (LAM) on hepatitis B.METHODS: A total of 156 cases were randomly chosen as study subjects from 317 patients with chronic hepatitis B (CHB). HBV genotypes were determined by PCR-microcosmic nucleic acid cross-ELISA. YMDD mutations were detected by microcosmic nucleic acid cross-nucleic acid quantitative determination. HBV DNA was detected by fluorescence ratio PCR analysis.LAM was given to 81 cases and its curative effect was observed by measuring ALT, HBV DNA load, HBeAg, and HBeAg/HBeAb conversion rate.RESULTS: HBV genotypes B, C, D, and non-classified genotypes were found in Guangxi Zhuang population.accounting for 25.6%, 47.4%, 58.3%, and 16.0%,respectively. Seventy-four cases were CD-, CB-, BD-mixed genotypes (47.7%). Forty-six (29.5%) cases had YMDD mutations. Genotype B was mostly found in mild and moderate CHB patients. Genotypes C, D and mixed genotype mostly occurred in severe CHB cases.Genotypes D and CD HBV-infected patients had higher ALT and HBV DNA than patients with other types of HBV infection. There was no significant difference among the genotypes in YMDD mutations, clinical types, ALT and HBV DNA level. Non-classified types geno had a significantly lower positive rate of HBeAg than other genotypes (x2= 12.841, P＜0.05). There was no significant difference in ALT recovery rate, HBV DNA load, HBeAg,and HBeAg/HBeAb conversion rate, 48 wk after LAM treatment between groups of genotypes D, CD, and nonclassified type.CONCLUSION: Genotypes B, C, and D, non-classified and mixed genotype of HBV are identified in the Guangxi Zhuang population. Variations in genotypes are associated with clinical severity and serum ALT levels, but not with YMDD mutation or HBV DNA load.Therapeutic effects of LAM on clinical parameters are not influenced by differences in genotypes. Further studies are needed to gain an in-depth understanding of the relationship between HBV genotypes and serum HBeAb and HBeAg.