A quasi-monoclonal anti-HBs response can lead to immune escape of ‘wild-type’ hepatitis B virus

Controversies in Treating Chronic Hepatitis B Virus Infection: Discordant Serologic Results

Despite effective vaccines and approved therapeutic agents, hepatitis B virus (HBV) remains a prevalent global health problem. Current guidelines rely on a combination of serologic, virological, and biochemical markers to identify the phase in the natural history of chronic HBV infection. Discordant serologic results can occur, which may lead to misclassification. Commonly encountered results that differ from the typical profiles seen in chronic HBV infection are described. For each scenario, the frequency of occurrence, possible explanations, and recommendations for clinical management are discussed. Recognition of discordant serologic findings is crucial for optimal clinical decision.

Analysis of serum hepatitis B virus RNA levels among HBsAg and HBsAb copositive patients and its correlation with HBV DNA

ABSTRACT

There are approximately 2 billion HBV-infected individuals worldwide, and approximately 1.87% to 7% of these individuals are copositive for HBsAg and HBsAb.Our study detected hepatitis B virus pgRNA (HBV RNA) levels in HBsAg and HBsAb copositive patients and then analyzed the correlation with HBV DNA, HBsAg, ALT, and AST levels. A total of 149 HBsAg and HBsAb copositive patients were identified from 66,617 outpatients.HBV RNA, HBV DNA, HBsAg, ALT, and AST serum levels were significantly different in different natural phases of HBV infection (immune tolerance phase, immune clearance phase, low replication phase, and reactivation phase) with statistical significance (P < .01). HBV RNA levels were positively correlated with HBV DNA, HBsAg, ALT, and AST levels. HBV RNA and HBV DNA levels were significantly increased in the HBeAg-positive group (66 patients) compared with the HBeAg-negative group (83 patients) (P < .01). In the HBeAg-positive group, HBV RNA levels were positively correlated with HBV DNA and HBsAg levels. In the HBeAg-negative group, HBV RNA levels were positively correlated with HBV DNA. Serum HBV RNA levels were positively correlated with HBV DNA, HBsAg, ALT, and AST levels.HBV RNA could be used as a virological indicator for antiviral therapy in HBsAg and HBsAb copositive hepatitis B patients.

In silico analysis of mutations associated with occult hepatitis B virus (HBV) infection in South Africa

Occult hepatitis B virus (OBI) infection is defined by the presence of viral DNA in the liver and/or serum in absence of hepatitis B surface antigen (HBsAg). While multiple studies have identified mutations that are associated with OBI, only a small portion of these mutations have been functionally characterized in vitro. Using complementary in silico approaches, the effects of OBI-associated amino acid mutations on HBV protein function in HBV/HIV-positive ART-naïve South Africans were evaluated. Two OBI-associated mutations in the PreS1 region, one in the PreS2 region, and seven in the surface region of subgenotype A1 sequences were identified as deleterious. In subgenotype A2 sequences, 11 OBI-associated mutations in the PreS1 region, seven in the PreS2 region, and 31 in the surface region were identified as deleterious. In the polymerase region, 14 OBI-associated mutations in subgenotype A1 and 71 OBI-associated mutations in subgenotype A2 were identified as deleterious. This study utilized in silico approaches to characterize the likely impact of OBI-associated mutations on viral function, thereby identifying and prioritizing candidates and reducing the significant cost associated with functional studies that are essential for mechanistic studies of the OBI phenotype.

The variability of hepatitis B envelope is associated with HBs antigen persistence in either chronic or acute HBV genotype A infection

BACKGROUND

More than 240 million people are chronically infected by hepatitis B virus (HBV) worldwide. Envelope proteins play a crucial role in viral cellular entry and immune recognition. The loss of HBs antigen (HBsAg) correlated with a good clinical prognosis is rarely achieved with or without treatment (3-16%).

OBJECTIVES

HBV envelope variability was investigated according to HBsAg persistence.

STUDY DESIGN

The cohort consisted of 15 HBV genotype A-infected patients divided into "resolvers", with HBsAg clearance, and "non-resolvers", with HBsAg persistence and in subgroups: acute (n=5, AHBV) or chronic infection (n=4, CHBV) and HBV/HIV coinfection (n=6, CHBV/HIV). HBV S and preS sequences were studied by direct and ultra-deep sequencing. Amino acid sequences were analyzed with bioinformatics for predicted antigenicity.

RESULTS

In S gene, the complexity was lower in AHBV than in chronic-infected patients (p=0.046). Major mutations, detected using direct sequencing, were more frequent in AHBV developing chronicity (p=0.01) than in AHBV resolvers. In the Major Hydrophilic Region, more frequent mutations were observed in non-resolvers versus resolvers (p=0.047) and non-resolvers tended to have more haplotypes with a reduced predicted antigenicity (p=0.07). Most of the mutations in preS/S region were found rather in epitopic than in non-epitopic areas (p=0.025). Interestingly, the mutation sY161F found in 3/8 non-resolvers was associated with a decrease in predicted antigenicity (28%; AnTheProt).

CONCLUSIONS

HBsAg persistence was correlated with mutations and deletions in areas playing a key role in immune recognition. These data suggest that variability in HBV envelope could favor immune escape in various clinical settings of HBV genotype A-infected patients.

Impact of deletions and mutations in Hepatitis B virus envelope proteins on serological profile and clinical evolution

The Hepatitis B virus (HBV) envelope glycoproteins are essential for viral entry into the hepatocyte and are also targets for host immune response. The study of these proteins could allow us to highlight molecular hot points influencing HBV fitness, which would subsequently modify the clinical evolution of the disease, both under anti-viral therapy or without treatment. The present short communication underlines the importance of the high variability in HBV envelope proteins, in regard with the literature and in our hands, for HBV-infected patients either on anti-HBV treatment or not. We report mutations in antigenic areas of S protein, i.e. CD8⁺/CD4⁺ T-cell epitopes and B-cell epitopes in the major hydrophilic region (MHR), such as sI126N and sG145R possibly involved in the rare coexisting Hepatitis B surface Antigen (HBsAg)/anti-HBs serological pattern. We mostly report serial mutations in preS region including preS1 deletion (aa 1-6, 31-71, 38-73, 72-104) and preS2 deletion (aa132-141) in patients with various clinical evolutions. Some of these viral envelope mutations, due to immune selection pressure, may result in a worsening of the hepatic disease.

Mutations in the S gene and in the overlapping reverse transcriptase region in chronic hepatitis B Chinese patients with coexistence of HBsAg and anti-HBs

Background

The mechanism underlying the coexistence of hepatitis B surface antigen and antibodies to HBsAg in chronic hepatitis B patients remains unknown.

Aims

This research aimed to determine the clinical and virological features of the rare pattern.

Methods

A total of 32 chronic hepatitis B patients infected by HBV genotype C were included: 15 carrying both HBsAg and anti-HBs (group I) and 17 solely positive for HBsAg (group II). S gene and reverse transcriptase region sequences were amplified, sequenced and compared with the reference sequences.

Results

The amino acid variability within major hydrophilic region, especially the “a” determinant region, and within reverse transcriptase for regions overlapping the major hydrophilic region in group I is significantly higher than those in group II. Mutation sI126S/T within the “a” determinant was the most frequent change, and only patients from group I had the sQ129R, sG130N, sF134I, sG145R amino acid changes, which are known to alter immunogenicity.

Conclusions

In chronic patients, the concurrent HBsAg/anti-HBs serological profile is associated with an increased aa variability in several key areas of HBV genome. Additional research on these genetic mutants are needed to clarify their biological significance for viral persistence.

Distribution and epidemiologic trends of HBV genotypes and subtypes in 14 countries neighboring china

BACKGROUND

The number of cases of HBV infection reported by the WHO for each district and country is positively correlated with the number of HBV sequences in the database isolated from the corresponding district and country.

OBJECTIVES

This study determined distribution characteristics of HBV genotypes and subtypes in 14 countries neighboring China. The progress made in genomic research involving HBV was also reviewed.

MATERIALS AND METHODS

Nine hundred fifty-one complete genome sequences of HBV from 14 countries neighboring China were selected from NCBI. The sequence-related information was analyzed and recorded. One hundred seventy-two sequences of HBV genotype B were screened for alignment using DNA star and MEGA 5.1.

RESULTS

Dominant HBV genotypes in the countries neighboring China were genotypes B, C and D and dominant subtypes were adw2 and adrq+. The association between genotype and serotype of HBV in these countries was shown to differ from previous research results. As shown by sequence alignment, the sequence divergence between five subgenotypes (B3, B5, B7, B8 and B9) was below 4%. The B subgenotypes shared six common specific amino acid sites in the S region.

CONCLUSIONS

The B3, B5, B7, B8 and B9 subgenotypes can be clustered into quasi-sub-genotype B3 and the open reading frame of HBV has a start codon preference; however, whether a mutation in the start codon in the pre-S2 region has an impact on survival and replication of HBV remains to be determined.

Establishment of a simple model for hepatitis B virus infection status based on trait marker from quantitative measurement of serum markers

The objectives of this study were to establish a simple model based on quantitative serum markers of hepatitis B virus (HBV) infection to understand the complex immune response to HBV. Patients samples were obtained from individuals with active HBV infection (alanine transaminase [ALT]-positive, aspartate aminotransferase [AST]-positive and HBsAg-positive), or patients who had recovered from infection (ALT-negative, AST-negative, anti-HBs-positive and either HBsAg, HBeAg, anti-HBe or anti-HBc positive). HBV quantitative markers, including HBsAg, anti-HBs, HBeAg, anti-HBe, and anti-HBc, were measured using a chemiluminescent microparticle immunoassay. Based on cut-off values, anti-HBs levels were converted to a ratio (sample value/cut-off value, RV). Anti-HBe and anti-HBc levels were determined using a competition method, resulting in the use of a ratio (cut-off value/sample value, RV) for determination of anti-HBe and anti-HBc values. The greater RV value in a patient was considered as a trait marker for HBV infection (TMHB) of this patient. Patients with TMHB including HBsAg or HBeAg were defined as TMHB-Ag; and patients with TMHB including anti-HBs, anti-HBe, or anti-HBc TMHB were defined as TMHB-Ab. The percentage of patients determined to be TMHB-Ag was 96.3% in the HBV group. The percentage of patients determined to be TMHB-Ab was 94.7% in recovery group. TMHBs could be used to analyze different status of HBV infection.

Analysis of complete nucleotide sequences of Angolan hepatitis B virus isolates reveals the existence of a separate lineage within genotype E

Hepatitis B virus genotype E (HBV/E) is highly prevalent in Western Africa. In this work, 30 HBV/E isolates from HBsAg positive Angolans (staff and visitors of a private hospital in Luanda) were genetically characterized: 16 of them were completely sequenced and the pre-S/S sequences of the remaining 14 were determined. A high proportion (12/30, 40%) of subjects tested positive for both HBsAg and anti-HBs markers. Deduced amino acid sequences revealed the existence of specific substitutions and deletions in the B- and T-cell epitopes of the surface antigen (pre-S1- and pre-S2 regions) of the virus isolates derived from 8/12 individuals with concurrent HBsAg/anti-HBs. Phylogenetic analysis performed with 231 HBV/E full-length sequences, including 16 from this study, showed that all isolates from Angola, Namibia and the Democratic Republic of Congo (n = 28) clustered in a separate lineage, divergent from the HBV/E isolates from nine other African countries, namely Cameroon, Central African Republic, Côte d'Ivoire, Ghana, Guinea, Madagascar, Niger, Nigeria and Sudan, with a Bayesian posterior probability of 1. Five specific mutations, namely small S protein T57I, polymerase Q177H, G245W and M612L, and X protein V30L, were observed in 79-96% of the isolates of the separate lineage, compared to a frequency of 0–12% among the other HBV/E African isolates.

N-glycosylation mutations within hepatitis B virus surface major hydrophilic region contribute mostly to immune escape

BACKGROUND & AIMS

HBV immune escape represents a challenge to prevention, diagnosis, and treatment of hepatitis B. Here, we analyzed the molecular and clinical characteristics of HBV immune escape mutants in a Chinese cohort of chronically infected patients.

METHODS

Two hundred sixteen patients with HBsAg and anti-HBs were studied, with one hundred eighty-two HBV carriers without anti-HBs as a control group. Recombinant HBsAg bearing the most frequent N-glycosylation mutations were expressed in CHO and HuH7 cells. After confirming N-glycosylation at the most frequent sites (129 and 131), together with inserted mutations, functional analysis were performed to study antigenicity and secretion capacity.

RESULTS

One hundred twenty-three patients had the wild-type HBs gene sequence, 93 patients (43%) had mutants in the major hydrophilic region (MHR), and 47 of the 93 patients had additional N-glycosylation mutations, which were transmitted horizontally to at least 2 patients, one of whom was efficiently vaccinated. The frequency of N-glycosylation mutation in the case group was much higher than that of the control group (47/216 vs. 1/182). Compared with wild-type HBsAg, HBsAg mutants reacted weakly with anti-HBs using a chemiluminescent microparticle enzyme immunoassay. Native gel analysis of secreted virion in supernatants of transfected HuH7 cells indicated that mutants had better virion enveloping and secretion capacity than wild-type HBV.

CONCLUSIONS

Our results suggest that specific HBsAg MHR N-glycosylation mutations are implicated in HBV immune escape in a high endemic area.

Probable corticosteroid-induced reactivation of latent hepatitis B virus infection in an HIV-positive patient involving immune escape

We describe a patient infected with human immunodeficiency virus who possessed a serological profile suggesting a previous cleared acute hepatitis B virus (HBV) infection, including high levels of antibodies against HBV surface antigen (anti-HBs). Following the administration of inhaled glucocorticosteroids combined with protease inhibitor-based antiretroviral treatment, the patient developed an unexpected severe acute hepatitis despite persistence of anti-HBs. A genotype A2 strain emerged with 2 major mutations in the S gene, sK122R and sD144E. Molecular and biological analyses strongly suggested reactivation of a latent HBV infection. The importance and the molecular basis of these 2 epitopes in immune-escape mechanisms and host-virus interactions are discussed.

Molecular and serological characterization of hepatitis B virus genotype A and D infected blood donors in Poland

Hepatitis B virus (HBV) genotypes have distinct geographical distributions and influence severity of clinical outcome and response to antiviral therapies. HBV polymorphism in HBV surface antigen (HBsAg) positive first time blood donors from Poland was examined. HBV serological markers and HBV DNA were tested in 170 samples. Whole genome (n = 53) or specific region sequences: pre-S/S and basic core promoter/precore (BCP/PC) region (91 and 154 samples, respectively) were phylogenetically analyzed. The median age of infected donors was 21 years. Anti-HBs, anti-HBe and hepatitis B e antigen were detected in 5%, 92.4% and 10.5% of tested donors, respectively. The HBV DNA load ranged between unquantifiable and 3.1 x 10(10) IU/mL (median: 4.10 x 10(3) IU/mL). Genotypes A2 (81.2%) and D (18.8%) co-circulated. Phylogenetic analyses revealed differences between the genotypes. Viral load and level of HBsAg tended to be lower in genotype D. The median HBsAg/HBV DNA ratio expressed in IU/mL was one for both genotypes, but very low or very high ratios appeared more frequent in genotype D infections. Higher amino acid variability in the surface proteins (median: 4%vs 1.5%; P = 0.01) and in the major hydrophilic region was observed in genotype D (P = 0.01). BCP/PC region analysis revealed the double mutation 1762T/1764A in 49/125 (39.2%) genotype A2 and 6/29 (20.7%) genotype D strains (P = 0.08). Mutations in PC and BCP regions correlated neither with HBsAg nor HBV DNA levels. HBV genotype A2 is dominant in HBsAg positive donors in Poland. Minority genotype D strains are significantly more substituted than genotype A2 strains potentially affecting the course of infection.

Randomized controlled study investigating viral suppression and serological response following pre-S1/pre-S2/S vaccine therapy combined with lamivudine treatment in HBeAg-positive patients with chronic hepatitis B

The aim of the current study was to evaluate viral suppression following combined treatment with an S/pre-S1/pre-S2 vaccine and lamivudine in patients with chronic hepatitis B. We established a randomized, controlled clinical trial to compare the responses of three different treatment groups: those receiving vaccine monotherapy, lamivudine monotherapy, or combination treatment. Viral response was evaluated via hepatitis B virus (HBV) DNA suppression using different levels of classification. Seroconversion was evaluated via HBeAg loss, HBeAg seroconversion, HBsAg loss, and anti-HBs response. We found that the group receiving combination treatment demonstrated a significant increase in viral suppression over that for the lamivudine or vaccine monotherapy group, although the HBeAg seroconversion rate was not different. This enhanced suppression effect in the combination group was reversed after the discontinuation of vaccine treatment, suggesting that booster doses are required for a sustained viral response. Anti-HBs was detected in 55/120 vaccine recipients, but only 3 patients demonstrated HBsAg loss, indicating that the vaccine-induced anti-HBs was unable to completely neutralize HBsAg in the serum. At the study end point, anti-HBs responders showed significantly higher HBeAg seroconversion rates, greater suppression of HBV DNA levels, and a lower median reduction in HBV DNA levels than those of anti-HBs nonresponders. Our results suggest that combined treatment with the vaccine and lamivudine was significantly more effective than lamivudine monotherapy in the short term and was especially successful in producing viral suppression and an enhanced anti-HBs antibody response.

Association of concurrent hepatitis B surface antigen and antibody to hepatitis B surface antigen with hepatocellular carcinoma in chronic hepatitis B virus infection

Antibody to hepatitis B surface antigen (HBsAg) (anti-HBs) can exist in patients with chronic hepatitis B virus (HBV) infection. To date, little is known about the association of concurrent HBsAg and anti-HBs (concurrent HBsAg/ anti-HBs) with hepatocellular carcinoma (HCC). The aim of this study was to investigate the clinical relevance of concurrent HBsAg/anti-HBs with preS deletion mutations and HCC in chronic HBV infection. A total of 755 patients with chronic HBV infection were included consecutively at a tertiary center. Logistic regression analysis was used to identify risk factors for HCC, and serum HBV DNA was amplified, followed by direct sequencing to detect preS deletions. The prevalence of concurrent HBsAg/anti-HBs was 6.4% (48/755) and all HBVs tested were genotype C. HCC occurred more frequently in the concurrent HBsAg/anti-HBs group than in the HBsAg only group [22.9% (11/48) vs. 7.9% (56/707), P = 0.002]. In multivariate analyses, age >40 years [odds ratio (OR), 14.712; 95% confidence interval (CI), 4.365-49.579; P < 0.001], male gender (OR 2.431; 95% CI, 1.226-4.820; P = 0.011), decompensated cirrhosis (OR, 3.642; 95% CI, 1.788-7.421; P < 0.001) and concurrent HBsAg/anti-HBs (OR, 4.336; 95% CI, 1.956-9.613; P < 0.001) were associated independently with HCC. In molecular analysis, preS deletion mutations were more frequent in the concurrent HBsAg/anti-HBs and HCC groups than in the HBsAg without HCC group (42.3% and 32.5% vs. 11.3%; P = 0.002 and 0.012, respectively). In conclusion, concurrent HBsAg/anti-HBs is associated with preS deletion mutations and may be one of the risk factors for HCC in chronic HBV infection with genotype C.

Virologic characteristics of hepatitis B virus in patients infected via maternal-fetal transmission

AIM

To determine whether HBV with the same characteristics causes dissimilar mutations in different hosts.

METHODS

Full-length HBV genome was amplified and linked with pMD T18 vector. Positive clones were selected by double-restriction endonuclease digestion (EcoRI and HindIII) and PCR. Twenty seven clones were randomly selected from an asymptomatic mother [at two time points: 602 (1 d) and 6022 (6 mo)] and her son [602 (S)], and the phylogenetic and mutational analysis was performed using BioEditor, Clustal X and MEGA software. Potential immune epitopes were determined by the Stabilized Matrix Method (SMM), SMM-Align Method and Emini Surface Accessibility Prediction.

RESULTS

All of the 27 sequences were genotype C, the divergence between the mother and son was 0%-0.8%. Compared with another 50 complete sequences of genotype C, the mother and her son each had 13 specific nucleotides that differed from the other genotype C isolates. AA 1-11 deletion in preS1 was the dominant mutation in the mother (14/18). The 1762T/1764A double mutation existed in all clones of the mother, 3 of them were also coupled with G1896A mutation, but none were found in the son. 17 bp deletion starting at nucleotide 2330 was the major mutation (5/9) in the son, which caused seven potential HLA class I epitopes and one B cell epitope deletion, and produced a presumptive new start codon, downstream from the original one of the P gene.

CONCLUSION

The HBV strain in the son came from his mother, and discrepant mutation occurred in the mother and her son during infection.

Mutation spectra of the surface-protein-coding region of the HBV genome in HBV-vaccinated and non-vaccinated individuals in Hungary

Hepatitis B virus (HBV) infection has a major effect on health care systems, with about one-third of the world's population currently infected with the virus. There is an effective vaccine against HBV, which contains a recombinant "surface antigen" produced in an expression vector. Vaccination has proved to be successful in Hungary: the number of acute HBV cases has decreased in the past 10 years. Although an increasing number of publications report on "vaccine-escape" HBV variants which can infect HBV-vaccinated individuals, such mutant HBV strains have not yet been detected in Hungary. We therefore surveyed two risk groups for vaccine-escape or immunoglobulin-escape HBV mutations in Hungary: 28 actively and/or passively HBV-immunized children of HBV carrier mothers who proved to be HBsAg and/or anti-HBc positive and 40 symptomless HBV carrier pregnant women (presumably carrying genotype B or C). We focused on the coding sequences of the "a" immundominant region of the surface protein. We could not detect the G145R amino acid substitution associated with vaccine escape mutant virus. However, we could map other mutations potentially affecting the immunodominant "a" region of the HBV surface protein.

Rolling circle amplification, a powerful tool for genetic and functional studies of complete hepatitis B virus genomes from low-level infections and for directly probing covalently closed circular DNA

Complete characterization of the biological properties of hepatitis B virus (HBV) variants requires the generation of full-length genomes. The aim of this study was to develop new tools for the efficient full-length genome amplification of virus from samples with low viral loads. Rolling circle amplification (RCA) was used to amplify full-length HBV genomes from both sera and liver biopsy samples from chronic HBV carriers. Serum-derived relaxed circular HBV DNA could be amplified only after completion and ligation of plus-strand DNA. Covalently closed circular DNA (cccDNA) from liver biopsies could be amplified directly from as few as 13 copies, using RCA, followed by a full-length HBV PCR. Three serial liver biopsy samples were obtained from a lamivudine-resistant patient who cleared detectable serum HBV after adefovir dipivoxil was added to the lamivudine therapy and then seroconverted to anti-HBs. Only the genomes from the last biopsy specimen obtained after the emergence of lamivudine resistance contained the lamivudine resistance-associated mutations rtL180M and rtM204V ("rt" indicates reverse transcriptase domain). Defective genomes were also found in this biopsy sample. Genomes cloned from the liver biopsy specimens were transfected into HuH7 cells to study their replication competence and their susceptibility to lamivudine. RCA is a powerful tool for amplifying full-length HBV genomes and will be especially useful for the study of occult or inactive HBV infections and patients undergoing antiviral treatment. It can also be used to probe HBV cccDNA, the crucial intermediate in viral persistence and the archive of resistance mutations.

Clinical and virological significance of the co-existence of HBsAg and anti-HBs antibodies in hepatitis B chronic carriers

The co-existence of hepatitis B surface antigen (HBsAg) and anti-HBs antibodies (HBsAb) in serum of hepatitis B virus (HBV)-chronic carriers has been previously associated with HBsAg-amino acid (aa) substitutions. However, the aa pattern of HBV-reverse transcriptase (RT) and the clinical settings associated with this serological profile remain largely unknown. We studied thirteen HBsAg-positive/HBsAb-positive patients. Newly diagnosed HBsAg-positive/HBsAb-negative patients (n=51) served as controls. HBsAg/RT sequences were obtained using in-house protocols. HBsAg-positive/HBsAb-positive patients were predominantly immunosuppressed (69%). Five presented advanced liver fibrosis. HBV DNA >5.0 log(10) copies/ml was significantly more frequent than in controls. A significantly higher aa variability was observed versus controls within HBsAg major hydrophilic region (MHR), especially the a-determinant, and within RT for regions overlapping the MHR, the a-determinant, and HBsAg C terminal region where drug resistance mutations occur. Further studies are needed to determine whether this higher HBsAg/HBV-RT variability might favor dissemination of anti-HBsAb escape HBV mutants and concomitantly alter nucleos(t)ide analogs efficacy.

Quasispecies and its impact on viral hepatitis

Quasispecies dynamics mediates adaptability of RNA viruses through a number of mechanisms reviewed in the present article, with emphasis on the medical implications for the hepatitis viruses. We discuss replicative and non-replicative molecular mechanisms of genome variation, modulating effects of mutant spectra, and several modes of viral evolution that can affect viral pathogenesis. Relevant evolutionary events include the generation of minority virus variants with altered functional properties, and alterations of mutant spectrum complexity that can affect disease progression or response to treatment. The widespread occurrence of resistance to antiviral drugs encourages new strategies to control hepatic viral disease such as combination therapies and lethal mutagenesis. In particular, ribavirin may be exerting in some cases its antiviral activity with participation of its mutagenic action. Despite many unanswered questions, here we document that quasispecies dynamics has provided an interpretation of the adaptability of the hepatitis viruses, with features conceptually similar to those observed with other RNA viruses, a reflection of the common underlying Darwinian principles.

Dynamics of a hepatitis B virus e antigen minus population ascribed to genotype F during the course of a chronic infection despite the presence of anti-HBs antibodies

The in vivo evolution of genotype F HBV variants was recorded in a chronically infected patient throughout a 3-year observation period. Fluctuating levels of HBs Ag and anti-HBs antibodies were recorded, both of them cocirculating in peripheral blood samples at given times. Fifty S gene derived clones were sequenced and phylogenetically analyzed. As expected, some amino acid replacements within the S ORF were also observed within the P ORF while others were silent for the former. Such change was statistically significant for both S and P overlapping genes, which clearly indicates the appearance of a positive selection pressure. Supporting this notion, amino acid replacements were documented at both B and T cell epitopes in samples from 1997 and 1998. Several mutations were documented within and outside the "a" determinant in the major hydrophilic region. Such substitutions might have resulted from the attempt of HBV to evade both humoral and/or cellular immune response. To the best of our knowledge this unusual profile of HBV variants in presence of usually "neutralizing" anti-HBs antibodies was examined in vivo for the first time.

Surveillance for hepatitis B surface antigen mutants

Hepatitis B viral (HBV) mutants can emerge in patients as a result of selection pressure from treatment options. Some mutations that occur in the immunodominant "a" determinant of hepatitis B surface antigen (HBsAg) can present as false negative results in HBsAg immunoassays. The mutation position in HBsAg and the type of mutation impacts immunoassay performance. HBsAg mutants will continue to emerge in response to selection pressure, therefore an appropriate HBV immunoassay-testing algorithm needs to be established to ensure their detection. Mutant surveillance programs can also contribute to our understanding of the changing epidemiology of HBV infection.

Coexistence of hepatitis B surface antigen (HBs Ag) and anti-HBs antibodies in chronic hepatitis B virus carriers: influence of "a" determinant variants

In chronic hepatitis B (CHB), the persistence of hepatitis B surface antigen (HBs Ag) is sometimes associated with antibodies (Ab) to HBs (anti-HBs). To assess the hypothesis of the selection of HBs Ag immune escape variants in CHB patients, the variability of the HBV S gene was determined for patients persistently carrying both HBs Ag and anti-HBs antibodies and patients solely positive for HBs Ag. We selected 14 patients who presented both markers (group I) in several consecutive samples and 12 patients positive for HBs Ag only (group II). The HBs Ag-encoding gene was amplified and cloned, and at least 15 clones per patient were sequenced and analyzed. The number of residue changes within the S protein was 2.7 times more frequent for group I than for group II patients and occurred mostly in the "a" determinant of the major hydrophilic region (MHR), with 9.52 versus 2.43 changes per 100 residues (P = 0.009), respectively. Ten patients (71%) from group I, but only three (25%) from group II, presented at least two residue changes in the MHR. The most frequent changes in group I patients were located at positions s145, s129, s126, s144, and s123, as described for immune escape variants. In CHB patients, the coexistence of HBs Ag and anti-HBs Ab is associated with an increase of "a" determinant variability, suggesting a selection of HBV immune escape mutants during chronic carriage. The consequences of this selection process with regard to vaccine efficacy, diagnosis, and clinical evolution remain partially unknown.

[New virologic tests and their application in management of chronic hepatitis B]

Virologic testing and clinical management of patients with chronic hepatitis B must take into account the particular characteristics of this virus. These tests rely on the detection of different viral genotypes and mutations that may cause viral escape to either the host immune response or the antiviral treatment. Tests to quantify viral load are important for studying the efficacy of antiviral treatments and especially because the pathogenesis of hepatic lesions requires viral replication. Appropriate management of chronic hepatitis B must rely not only on the standard serologic markers but also on tests that quantify viral load and on the study of viral genome variability according to clinical situation.