Genotypic differences in the hepatitis B virus core promoter and precore sequences during seroconversion from HBeAg to anti-HBe

Hepatitis B virus (HBV) strains from anti-HBe positive patients often show specific mutations in the precore gene, the core promoter region, or both. The dynamics of seroconversion in relation to the appearance of these mutations has not been studied and compared between defined HBV genotypes. Samples from patients followed during seroconversion from HBeAg to anti-HBe were amplified by polymerase chain reaction (PCR), sequenced and genotyped. Among 16 sets of samples, 6 belonged to genotype A, 6 to genotype D, 2 to genotype B, 1 to genotype C, and 1 to genotype E. Whereas strains from genotypes B, C and E showed changes in the core promoter, precore codon 28 or both, genotype A and D strains displayed a different pattern. In 4 of 6 anti-HBe positive samples from genotype A, the precore had a wild-type sequence while the core promoter sequence showed a specific TGA mutation. In another genotype A strain a precore stop mutation was preceded by a mutation in codon 15, thus conserving base-pairing at the pregenomic RNA level in this region. In contrast, all genotype D strains showed wild-type sequences in both the core promoter and precore codon 28 in pre- and post-seroconversion samples. Thus, in 8 patients with a mean follow-up time of 17 months, wild-type sequences in both the core promoter and precore codon 28 were found after seroconversion to anti-HBe. This study also confirmed, for genotype D, that HBeAg seroconversion often occurs earlier than genomic conversion.     

Presence of hepatitis B virus core promoter mutations pre-seroconversion predict persistent viral replication after HBeAg loss.

BACKGROUND: In patients with chronic hepatitis B virus (HBV) infection DNA levels do not always fall after anti-hepatitis B e (anti-HBe) seroconversion. OBJECTIVES: To follow longitudinally through HB e antigen (HBeAg) loss HBV DNA levels and core promoter/precore sequences in a cohort of 21 chronic HBV carriers. STUDY DESIGN: Treatment-na?ve HBeAg seropositive HBV carriers were monitored through HBeAg loss for between 2 and 22 years (mean 9.3). Core promoter/precore sequences, genotypes, HBV DNA levels and HBe status were determined. RESULTS: Patients were grouped into those in whom serum/plasma HBV DNA remained high after HBeAg loss (group 1, n=11; HBV DNA>5log(10)IU/ml) and those in whom HBV DNA declined (group 2, n=10). Re-appearance of HBeAg was seen in seven group 1 patients. Pre-seroconversion mutations in the core promoter region including A1762T and/or G1764A were detected more frequently in group 1 (P=0.031). Overall sequence changes at sites other than 1762/1764 were more common post-seroconversion in group 1 than group 2 patients (P=0.037). CONCLUSIONS: The presence of core promoter mutations prior to HBeAg loss identified those patients in whom HBV DNA persisted at high levels and was associated with temporary re-emergence of serum HBeAg. These patients may benefit from early anti-viral treatment.     

A case-control study for early prediction of hepatitis B e antigen seroconversion by hepatitis B virus DNA levels and mutations in the precore region and core promoter

Factors influencing and predictive of seroconversion from hepatitis B e antigen (HBeAg) to antibody (anti-HBe) were sought in a case-control study of 61 patients with chronic hepatitis B who had been observed from 5 years before to 1 year after seroconversion, and 32 patients who did not seroconvert during the entire 6-year period. Almost all of the patients (96%) were infected with HBV genotype C. HBV DNA levels began to decrease 3 years before seroconversion in the seroconverters, while they remained high in the non-converters. The frequency of precore mutation and the loss of HBeAg (A1896) started to increase 1 year before in the converters, and became significantly higher at seroconversion (23 vs. 3%, P = 0.030) than that in the non-converters. Double mutation in the core promoter (T1762/A1764) was more common in the seroconverters than in the non-converters 5 years before seroconversion (48 vs. 28%), and became significantly more frequent at seroconversion (65 vs. 41%, P = 0.046). Seroconversion occurred in 75% of the patients with at least HBV DNA levels <5.5 logarithmic equivalents/mL; precore mutation in 20% or more of HBV DNA; or core promoter mutation. Seroconversion occurred in 50% of those patients within 1 year, 88% within 2 years, and 93% within 5 years. These results indicate that a decrease in HBV DNA levels and mutations in the precore region and the core promoter were associated significantly and complementarily with seroconversion, and each of them or a combination thereof was predictive of seroconversion years ahead.     

Evolution of precore/core promoter mutations in hepatitis B carriers with hepatitis B e antigen seroreversion

The evolution of precore stop codon mutation (A1896) and dinucleotide mutation (T1762/A1764) in the basic core promoter (BCP) of hepatitis B virus (HBV) genome during transient seroconversion and seroreversion of hepatitis B e antigen (HBeAg) remains unclarified. Five HBeAg-positive HBV carriers who experienced transient seroconversion followed by seroreversion of HBeAg (Group I, 3.3%) and 3 HBeAg-negative HBV carriers with documented reversion of HBeAg (Group II, 2.5%) in a prospective cohort of 272 patients with chronic hepatitis B were thus identified. The sequential changes at the precore nucleotide 1896 and BCP dinucleotide 1762/1764 were determined by polymerase chain reaction and direct sequencing. At enrollement, precore A1896 and BCP T1762/A1764 were noted in 4 (50%) and 1 (13%) of the eight patients. During a median follow-up period of 58 months (range: 31-76 months), 12 episodes of transient HBeAg seroconversion followed by seroreversion were encountered in Group I patients and 3 episodes of HBeAg seroreversion in Group II patients. Accompanying acute exacerbations were found in two-thirds of patients with either HBeAg seroconversion or seroreversion. Overall, precore nucleotide A1896 remained identical in 73% and 83% of the seroconversion and seroreversion events, respectively. BCP dinucleotide T1762/A1764 remained unchanged in 94% and 92% of the seroconversion and seroreversion events, respectively. At the end of follow-up, only one had both precore and BCP mutations. In conclusion, these data suggested that HBeAg seroreversion might be due to the lack of sustained precore and BCP mutations after HBeAg seroconversion. Although uncommon, HBeAg seroreversion can be associated with hepatitis exacerbation.     

Clinical and serological variation between patients infected with different Hepatitis B virus genotypes

Hepatitis B virus (HBV) has eight genotypes which have distinct geographical distributions. Studies comparing differences in the clinical outcomes of infections caused by strains with genotype-related variations in the HBV genome have largely compared genotypes B and C and genotypes A and D but not all four genotypes. The present study included 196 HBV-infected patients attending an infectious diseases outpatient clinic in Sweden. The age and geographic origin, liver function, HBeAg and anti-HBe status, and the presence or absence of HBV DNA were analyzed for each patient. HBV DNA was detected in 144 patients, and the HBV genotype and the core promoter and precore sequences were determined for the isolates from 101 of these patients. Among the patients who might be considered most likely to be nonviremic, namely, anti-HBe-positive HBV carriers with normal alanine aminotransferase (ALT) levels, 65% had detectable HBV DNA and were thus viremic. Among the viremic patients, HBeAg-positive patients were more likely to have elevated ALT levels than anti-HBe-positive patients. HBV genotypes A to F were represented in the study, and their distributions coincided accurately with the origin of the patient. A significantly higher number of genotype D-infected patients were anti-HBe positive and had elevated ALT levels (42% of genotype D-infected patients but 0% of patients infected with genotypes B and C). Genotype D strains with mutations in the core promoter and precore regions were significantly correlated with elevated ALT levels in the patients. The differences were not age related. Therefore, in this large-scale cross-sectional study, genotype D appears to be associated with more active disease.     

Genetic heterogeneity of the precore and the core promoter region of genotype C hepatitis B virus during lamivudine therapy

It has been reported that spontaneous or interferon (IFN)-induced hepatitis B e (HBe) seroconversion has usually been associated with the development of a stop codon in the precore region. However, the difference between lamivudine-induced seroconversion and spontaneous or IFN-induced seroconversion is not known. The aim of this study was to investigate the correlation between the evolution of the precore and core promoter mutations and lamivudine-induced seroconversion. Forty-five patients with chronic hepatitis B virus (HBV) infection who were treated with lamivudine for more than 1 year were enrolled. The nucleotide sequence of the precore and core promoter region was determined before and after treatment with lamivudine for 1 year. Among 29 patients who were hepatitis B e antigen (HBeAg)-positive before treatment, 12 (41.3%) lost HBeAg during the course of treatment for 1 year. Of these, eight patients (66.7%) still had precore wild type HBV after 1 year. After 1 year, reversion to precore wild type HBV was detected in 11 (64.7%) of 17 patients who had precore mutant HBV before treatment. Twelve (70.6%) of 17 patients who were persistently HBeAg-positive had precore wild type HBV before and after treatment for 1 year. Despite the loss of HBeAg, two thirds of the patients still had precore wild type HBV after the 1-year treatment. It is suggested that lamivudine-induced seroconversion differs from spontaneous or IFN-induced seroconversion in the change of nucleotides in the precore region. The reversion in the precore region may be caused by the difference of drug-susceptibility to lamivudine. The antiviral effect of lamivudine may be more effective in the precore mutant HBV than in the precore wild type HBV.     

阿德福韦酯治疗慢性乙型肝炎HBeAg血清学转换与基因型、HBV特异性CTL的关系

目的 探讨阿德福韦酯治疗慢性乙型肝炎患者发生HBeAg血清学转换与HBV基因型、HBV特异性CTL的关系.方法 70例慢性乙型肝炎患者HBV DNA阳性（HBV DNA≥1×104拷贝/ml）,HBeAg阳性45例,其中B基因型23例（51.11%）,C基因型22例（48.89%）.ALT＞2×正常参考值上限（ULN）、人白细胞抗原（HLA）-A2阳性,用阿德福韦酯（正大天睛药业公司生产）10 mg,口服,每日1次.观察治疗12个月后HBeAg血清学转换与HBV基因型、HBV特异性CTL的关系.结果 阿德福韦酯治疗12个月后,HBV特异性CTL（0.68%±0.11%）高于治疗前（0.33%±0.11%）,t=8.36 P＜0.001,HBV DNA（3.01±0.2）log10拷贝/ml低于治疗前[（6.27 ±0.70）log10拷贝/ml]t=12.63 P＜0.001,HBV DNA阴转（＜500拷贝/ml）43例（61.43%）.HBeAg阳性45例中发生HBeAg转阴13例（28.89%）,HBeAg血清学转换8例（17.78%）,HBeAg血清学转换者HBV特异性CTL（0.86 ±0.05%）高于无HBeAg血清学转换者（37例,82.22%）的HBV特异性CTL（0.61%±0.07%）,t=7.88,P＜0.001.HBeAg血清学转换8例中,B基因型7例（占B基因型30.43%）,C基因型1例（占C基因型4.55%）,x2=5.15,P＜0.05.结论 阿德福韦酯能提高CHB患者的HBV特异性细胞免疫功能,治疗后HBeAg血清学转换的发生与HBV特异性CTL水平升高有关,并可能与基因型有关.     

HBe antigen loss during lamivudine therapy is not caused by mutations in precore and core promoter genes in patients with chronic hepatitis B

HBe antigen (HBeAg) loss or seroconversion can occur during lamivudine therapy. The purpose of this study was to analyze nucleotide sequences in precore and core promoter regions, and examine the influence of mutations in these regions on the disappearance of HBeAg during lamivudine therapy. Serial serum samples were obtained from 51 patients (HBeAg loss in 26 patients) at commencement of therapy (baseline) and after 1 year of lamivudine therapy. Serum samples were amplified with PCR and nucleotide sequences of HBV were analyzed. At baseline, a precore stop codon mutation (A1896) was identified in 8 of 26 HBeAg loss patients and in 8 of 25 HBeAg non-loss patients. At 1 year, precore mutation was observed in 4 of 14 patients analyzed who showed HBeAg loss. At 1 year, however, a precore mutation was observed also in 3 of 9 analyzed patients who showed no HBeAg loss. Core promoter mutations were noted in 21 of 26 HBeAg loss patients and in 20 of 25 HBeAg non-loss patients. At 1 year, core promoter mutations were noted in 11 of 14 HBeAg loss patients and in 8 of 9 HBeAg non-loss patients. Our data suggested that during lamivudine therapy, core promoter and precore mutations do not influence HBeAg loss or seroconversion but may reduce the viral level upon HBeAg loss or seroconversion.     

Hepatitis B e antigen‐negative mutations in the precore and core promoter regions in Korean patients

Most patients with hepatitis B e antigen (HBeAg)‐negative chronic hepatitis B have variants of the hepatitis B virus (HBV) that include mutations in the precore or core promoter regions of the HBV genome. The aim of this study was to investigate the patterns of precore and core promoter mutations and their relationship to HBeAg expression in Korean patients. Four hundred seventy‐five Korean patients with chronic HBV infection between February 1995 and December 2003 were enrolled in this study. There were 236 HBeAg‐positive and 239 HBeAg‐negative patients. Blood samples were tested for HBsAg, anti‐HBs, HBeAg, hepatitis B e antibody (anti‐HBe), liver function tests, and serum HBV DNA. Mutations in the precore and core promoter regions were determined by direct sequencing. In the core promoter region, the C1740, C1753, T1762/A1764, and T1766 mutations were associated with HBeAg escape (all; P < 0.05). In the precore region, a higher frequency of the C1802, A1828, T1846, A1850, C1858, T1862, and A1896 mutations was found in HBeAg‐negative patients (all; P < 0.05). In particular, the A1896 mutation was associated with high serum levels of ALT and HBV DNA in HBeAg‐negative patients (P = 0.014 and 0.026, respectively). Mutations around the Kozak sequence (nucleotides 1809–1812) were found in 6.7% of patients and were not associated with undetectable HBeAg (P = 0.13). In Korean patients, various mutations in the precore and core promoter regions were associated with HBeAg escape and amelioration of hepatic inflammation in HBeAg‐ negative patients. Only the A1896 mutation contributed to HBeAg‐negative chronic hepatitis B. J. Med. Virol. 81:594–601, 2009 © 2009 Wiley‐Liss, Inc.     

Diagnosing different stages of hepatitis B infection using a competitive polymerase chain reaction assay

PURPOSE: Different stages of hepatitis B virus (HBV) infection can be defined by serum HBV DNA levels. This study attempts to (1) investigate serum HBV DNA levels in inactive carriers and patients with chronic HBV (CHB) infection and (2) define cut-off value between inactive carriers and HBeAg (precore antigen of HBV) negative CHB patients in Indian population. METHODS: One hundred and forty samples encompassing 42 inactive HBsAg carriers and 98 CHB patients (53 HBeAg-positive and 45 HBeAg-negative) were analysed. Serum HBV DNA levels were determined employing an in-house competitive polymerase chain reaction (cPCR) assay. RESULTS: The HBeAg-positive patients were found to have the maximum median HBV DNA load, which was significantly higher than the HBeAg-negative ones (median; 1.25 x 10(8) vs. 2.30 x 10(5) copies/mL ; P<0.05). Interestingly, the latter group has significantly higher HBV DNA levels than the inactive carriers (median; 2.30 x 10(5) vs. 4.28 x 10(3) copies/mL; P<0.05). The 2.5 x 10(4) copies/ml HBV DNA levels were optimal for discriminating CHB patients (HBeAg-negative) from inactive carriers with 75.6 and 78.6% sensitivity and specificity, respectively. CONCLUSIONS: Despite the extensive overlapping of HBV DNA levels in inactive carriers and HBeAg negative CHB patients, 2.5 x 10(4) copies/mL is the most favourable cut-off value to classify these individuals and would be imperative in the better management of this dreadful disease.     

Genetic characteristics of hepatitis B virus genotypes as a factor for interferon-induced HBeAg clearance

The factors determining the responsiveness of different hepatitis B virus (HBV) genotypes to interferon treatment are not fully understood. We investigated the relationship between HBV genetic characteristics and the outcome of short (16 weeks) or prolonged (32 weeks) treatment with standard interferon-alpha in a prospectively followed cohort of 103 patients across Europe with HBeAg positive chronic hepatitis B. INNO-LiPA assays and HBV DNA sequencing were used to determine HBV genotypes, mutations in the core promoter and precore/core regions. After 16-weeks interferon-alpha treatment, the rate of HBeAg clearance was higher in genotype A versus all other genotypes (P = 0.014), or genotype D alone (P = 0.05). The HBV genome analysis revealed that: (i) after 16-weeks treatment, an HBV subpopulation with core promoter mutations emerged or increased (P < 0.001) only in genotype A; (ii) the core gene of genotype A has the lowest number of amino acid variations in comparison with genotypes B, C, or D. Logistic regression analysis identified genotype A as a positive predictor of short (16 weeks) treatment response (P = 0.001; odds ratio 6.19, 95 confidence interval 1.94-19.8), having a greater impact than baseline HBV DNA or alanine aminotransferase (ALT) levels. In contrast, the response to prolonged interferon-alpha treatment was not different between HBV genotypes. These results suggest that HBV genotype A responds earlier to interferon treatment than other genotypes, which is associated with its molecular characteristics. The optimal duration of interferon-based therapies in chronic hepatitis B may vary between different HBV genotypes.     

Epidemiology of precore mutants of hepatitis B in the United Kingdom

A point mutation assay was used to study the codon 28 and codon 1 precore mutant status of 310 chronic hepatitis B carriers (82 HBeAg positive and 228 HBeAg negative). Fourteen of 228 (6%) of HBeAg negative carriers had high levels of serum HBV DNA. Nine of these were explained by precore variants, three by core promoter variants, and two were not explained by recognised precore changes. Nested PCR detected serum HBV DNA in 36% (82/228) of HBeAg negative carriers and 63% (52/82) of these had precore variants. Four of 82 (4%) of the HBeAg positive carriers had precore variants, all as mixed mutant/wild type populations and evidence indicated that these carriers were seroconverting. Overall 23% (52/228) of HBeAg negative carriers had both serum HBV DNA and codon 1 or 28 precore mutations. A sexual transmission event from an HBeAg negative carrier with a relatively low serum HBV DNA level (10(4)-10(6) genome copies/ml) and only core promoter mutations was observed. Despite high rates of variant carriage in the antenatal sub-group perinatal transmission was not observed. The results of direct sequencing on 45 carriers validated the point mutation assay and also showed that codon 28 mutations were only seen in carriers with the genotype CCT at codon 15. For the Caucasian population a higher prevalence of codon 28 mutations (13/25 or 52%) than expected was seen. Liver biopsy data indicated that there was no link between the presence or absence of precore mutants and the severity of liver disease.     

重型肝炎时乙型肝炎病毒基因型与基本核心启动子及前C区突变关系的研究

目的探讨重型肝炎（重肝）乙型肝炎病毒（HBV）基因型与基本核心启动子（BCP）及前C区突变的关系。方法采用聚合酶链反应（PCR）-限制性片段长度多态性分析技术（PCR-RFLP）对52例重肝和52例慢性乙肝（CHB）进行HBV基因分型。采用PCR产物直接测序技术，随机对15例B型和15例C型重肝患者的BCP区和前C区进行序列测定，分析HBV基因型与BCPT1762／A1764及前C区A1896突变的关系。结果泉州地区重肝的基因型以B型为主（48．08％），其次为C型（30．77％）和B／C混合型（17．31％），无A、E、F型存在。与CHB组比较，重肝组B型检出率明显降低，而C型和BIC混合型检出率明显升高。C型重肝患者BCPT1762／A1764双突变率显著高于B型（P〈0．05），而前C区A1896突变率在B、C型感染者中差异无统计学意义（P〉0．05）。结论C型感染易引起较重肝损伤，而B／C型混合感染可能是导致重肝发生的重要原因之一。C型重肝患者BCP T1762／A1764双突变率显著高于B型。     

Hepatitis B virus genotypes and spontaneous hepatitis B e antigen seroconversion in Taiwanese hepatitis B carriers

Hepatitis B virus (HBV) is classified into eight genotypes (A-H), and genotype C is associated with more aggressive liver disease compared to genotype B. However, the mechanisms responsible for the clinical differences remain unclear. To test whether genotype C patients had with lower rates of spontaneous hepatitis B ge antigen (HBeAg) seroconversion than genotype B patients, stored serum samples from 146 Taiwanese adult HBeAg-positive hepatitis B carriers followed-up for a mean of 52 months (range, 12-120 months) were tested for HBV genotype by a molecular method. Genotype C patients were significantly older than genotype B patients (mean age, 37 +/- 12 vs. 29 +/- 10 years, P < 0.001). During the follow-up period, genotype C patients had a significantly lower rate of spontaneous HBeAg seroconversion than genotype B patients (27 vs. 47%, P < 0.025). Spontaneous HBeAg seroconversion occurred one decade later in genotype C patients compared with genotype B patients. Multivariate analyses identified age < or =35 years (odds ratio: 2.08; 95% confidence interval [CI], 1.07-4.0; P < 0.05), high baseline serum alanine aminotransferase level (odds ratio: 2.34; 95%CI, 1.39-4.09; P < 0.005), and HBV genotype B (odds ratio: 1.94; 95%CI, 1.03-3.63; P < 0.05) as independent factors associated with spontaneous HBeAg seroconversion. In conclusion, genotype C patients, compared to genotype B patients, have a delayed HBeAg seroconversion in the immune clearance phase of chronic HBV infection, which may contribute to a more progressive liver disease and more refractory to antiviral therapy.     

Patients with and without loss of hepatitis B virus DNA after hepatitis B e antigen seroconversion have different virological characteristics

The characteristic differences between patients with and without loss of hepatitis B virus (HBV) DNA after achieving hepatitis B e antigen seroconversion were analyzed by comparing changes in HBV DNA and HBV core-related antigen levels during a period from 3 years before to 3 years after the seroconversion. Of the 24 seroconverters, 6 (inactive replication group) showed continuous loss of HBV DNA in serum after the seroconversion and the remaining 18 did not lose HBV DNA (active replication group). The HBV DNA level was similar between the two groups, while the HBV core-related antigen level was significantly lower in the active replication group than in the inactive replication group before the seroconversion. The levels of both HBV DNA and HBV core-related antigen decreased remarkably around the time of seroconversion in the inactive replication group, while these levels did not change or decreased slightly in the active replication group. After the seroconversion, the HBV DNA level was significantly higher in the active replication group than in the inactive replication group, while the HBV core-related antigen level was similarly low between the two groups. Because the serum level of HBV core-related antigen mainly reflects that of HBe antigen, the low level of HBV core-related antigen seen after seroconversion in both groups might have contributed to the occurrence of seroconversion. The precore and core promoter mutations which cause diminished excretion of hepatitis B e antigen were significantly more frequent in the active replication group than in the inactive replication group. It was therefore considered that the seroconversion was caused mainly by a decrease in viral replication in the inactive replication group, and mainly by a decrease in HBe antigen production in the active replication group.     

Tracking the naturally occurring mutations across the full-length genome of hepatitis B virus of genotype D in different phases of chronic e-antigen-negative infection

Hepatitis B e-antigen (HBeAg)-negative chronic HBV infection is highly prevalent in several parts of the world, including India, with the clinical spectrum ranging from inactive carrier (IC) state to chronic ‘e-negative’ hepatitis B (CHB) and culminating in advanced liver disease such as cirrhosis (LC). The present study has for the first time investigated the natural diversity of HBV belonging to genotype D in treatment-naïve Indian patients representing the above phases of HBeAg-negative infection to identify candidate mutations associated with each disease state. Studies of full-length HBV/D sequences revealed that the progressive accumulation and persistence of mutations in basal core promoter, negative regulatory element, Pre-core region, the B- and T-cell epitopes of X protein as well as deletions in the PreS region contribute significantly to disease progression from IC through CHB to LC. In addition, the development of CHB was associated with a significant increase in viral variants characterized by mutations in enhancer II, preS1 promoter, T-cell epitope of core and B-cell epitope region of PreS1. While few of the mutations were previously reported in the context of HBV genotypes B and C, others had not been documented before. Our results thus highlight a distinct pattern of mutation in HBV/D that may help in predicting clinical outcomes of HBeAg-negative infection and have implications for better clinical management of the patients.     

Effect of mutating the two cysteines required for HBe antigenicity on hepatitis B virus DNA replication and virion secretion

Hepatitis B virus (HBV) variants with impaired expression of e antigen (HBeAg) frequently arise at the chronic stage of infection, as exemplified by precore and core promoter mutants. Since an intramolecular disulfide bond maintains the secondary structure of HBeAg, we explored effect of missense mutations of either cysteine codon. Consistent with earlier reports, substitution of each cysteine rendered HBeAg nearly undetectable. With underlying nucleotide changes at the loop of pregenome encapsidation signal, the C-7 mutants were severely impaired in pregenomic RNA packaging and hence DNA replication. Although none of the missense mutations at C61 reduced DNA replication, replacement with arginine, but not alanine, aspartic acid, phenylalanine, or serine, blocked virion secretion. Consistent with the detection of C61R genome from a patient serum, secretion block of the C61R mutant could be overcome by co-expression of wild-type core protein. In conclusion, point mutations of the C61 codon may generate viable HBeAg-negative variants.     

Features and clinical implications of hepatitis B virus genotypes and mutations in basal core promoter/precore region in 507 Chinese patients with acute and chronic hepatitis B

BackgroundThe association of hepatitis B virus (HBV) genotypes and basal core promoter (BCP) and precore (PC) mutations with the clinical characteristics is increasingly recognized.ObjectiveTo investigate virologic features and clinical implications of HBV genotypes, BCP and PC mutations between large-size patients with acute hepatitis B (AHB) and chronic hepatitis B (CHB).Study designOne hundred and eighty-two AHB patients and 325 CHB patients were investigated. HBV genotypes and BCP/PC mutations were determined by direct sequencing. Mutations at 10 interested sites of the BCP/PC region were compared between the two groups of patients.ResultsAHB patients had a significantly higher ratio of genotype B to C than CHB patients (37.4–62.6% vs. 16.6–83.4%, P < 0.001). The prevalence of BCP/PC wild-type virus was 60.4% in AHB patients in contrast to 28.9% in CHB patients. Significantly lower prevalence of A1762T, G1764A, G1896A, and G1899A but higher prevalence of T1758C was found in AHB patients. Interestingly, T1758C and A1762T/G1764A appeared mutual restraint. Genotype B virus had lower BCP mutation frequency and similar PC mutation frequency compared to genotype C virus. AHB patients with BCP/PC mutant virus had higher viral load, whereas CHB patients with BCP/PC mutant virus had lower viral load and elevated alanine aminotransferase, in comparison with those with the wild-type virus.ConclusionPatients with genotype B virus, BCP/PC wild-type virus or T1758C mutant virus were more susceptible to develop AHB, whereas high prevalence of the BCP/PC mutations was associated with CHB development.     

Rapid and sensitive assays for determination of hepatitis B virus (HBV) genotypes and detection of HBV precore and core promoter variants

Hepatitis B virus (HBV) genotypes may influence HBeAg seroconversion rates, mutational patterns in the precore (PC) and core promoter (CP) regions, severity of liver disease, and response to antiviral treatment. Development of rapid, simple, and standardized assays to detect viral genotypes and common mutations in the PC and CP regions can accelerate research on the clinical significance of these variants. We aim to assess the accuracy of a line probe assay in determining HBV genotypes and detecting HBV PC and CP variants. HBV genotypes in 701 patients and PC and CP variants in 600 patients with chronic HBV infection from China and the United States were studied using the INNO-LiPA assay. All but one (99.9%) sample were classified by the genotyping assay. All eight genotypes, i.e., A to H, were found. The INNO-LiPA genotyping assay results were completely concordant with those of sequencing. Using the INNO-LiPA PC assay, 99.8 and 94.7% samples were classifiable in the PC and CP regions, respectively. The PC assay results were completely concordant with those of sequencing in all samples that showed either wild-type or variant sequence. The line probe assay was more sensitive in detecting mixtures than was direct sequencing. By INNO-LiPA, only 50 and 27% of the samples, with mixed wild-type and variant sequence in the PC and CP region, respectively, showed mixed sequence by direct sequencing. INNO-LiPA is rapid, sensitive, and reliable-thus enabling accurate determination of HBV genotypes and detection of PC and CP variants in a large population of patients.