Effect of Different Anti Viral Drugs on Hepatitis B Patients From Pakistan

Old and New Diagnostic Tools in the Current Management of Chronic Hepatitis BTanvir IbrahimPhD Scholar02-ARID-201ReferenceFernando BessoneLiver International.2014;34(7):991-1000.

ContentsIntroductionHBV StructureHBV Life CycleVariability Sources of MutantsDiagnosisEffects of Anti Viral DrugsObjectiveMethodologyReferences

Hepatitis B - IntroductionHepatitis B Virus (HBV) infection is one of the factor that cause the hepatitis which may eventually lead to liver cirrhosis and ultimately to death.The hepatitis B virus (HBV) transmissionbody fluids such as blood, semen, and vaginal secretions.

Hepatitis B - IntroductionSince the discovery of hepatitis B virus (HBV) by Blumberg in 1965, a wide variety of antigens and components of the virus has been detected. The increasing knowledge of these biological structures has improved our understanding of the viral cycle and provided a fruitful field for developing some useful tools for the clinical management of the disease.

Hepatitis B - IntroductionSince the discovery of hepatitis B virus (HBV) by Blumberg in 1965, a wide variety of antigens and components of the virus has been detected. The increasing knowledge of these biological structures has improved our understanding of the viral cycle and provided a fruitful field for developing some useful tools for the clinical management of the disease.

Hepatitis B - DiagnosisThe physical examination Routine Lab Investigation Serologic tests Viral Load or hepatitis B virus (HBV- DNA) Imaging studies Liver Biopsy & ??????

PrevalenceHepatitis B Virus (HBV) infection is a global health problemAbout 02 billion people >350 million of them CHBV infectionAbout over 600,000 deaths/year.

HBV - StructureThe human HBV Family HepednaviridaeAlso includes a variety of avian virusesMammalian viruses Share similar genomic organizationHBV StructureThe hepatitis B virus constituted by; It measures about 42 nm in diameterThe double shelled particle is called Dane ParticleThe antigenic components are HBsAgHBcAgHBeAgPartially double-strandedcircular DNA molecule

HBV Structure

HBV StructureHBV genomerelatively small partially double stranded Relaxed circular DNA (RC DNA) of 3.2 KbA full length minus (-) strand DNA with a terminal redundancy of 7 9 nucleotides &An incomplete plus (+) strand of variable length. Coding information is on the minus strand Four open reading frames (ORFs)The longest ORF encodes the viral polymerase.

HBV StructureFour overlapping ORFs:Surface geneThe S gene encodes the viral envelope. There are 5 mainly antigenic determinants: (1) a, common to all hepatitis B surface antigen (HBsAg), and (2-5) d, y, w, and r, which are epidemiologically important and identify serotypes.S (the surface, or envelope, gene): Encodes the pre-S1, pre-S2, and S proteinsHBV Structure

HBV StructureCore geneThe core antigen, HBcAg, is the protein that encloses the viral DNA. The e antigen, HBeAg, which is also produced from the region in and near the core gene, is a marker of active viral replication. Individuals who are infected with the wild type virus often have mixed infections, with core and precore mutants in up to 50% of individuals. They often relapse with HBeAg-negative disease after treatment.

HBV Structure

HBV StructureP (the polymerase gene): Encodes a large protein promoting priming ribonucleic acid (RNA) dependent and DNA-dependent DNA polymerase &ribonuclease H (RNase H) activities

HBV Structure

HBV StructureX geneThe role of the X gene is to encode proteins that act as transcriptional transactivators that aid viral replication. Evidence strongly suggests that these transactivators may be involved in carcinogenesis.

Viral Life CycleDuring infection blood - liver.Binds - susceptible hepatocytes - Pre S1 domain is Penetration - viral cores disassemble &genomic DNA nucleus - importin pathway. Inside nucleus Genomic RC DNA - covalently closed circular DNA (cccDNA) - repair enzymes. This ccc DNA minichromosome - transcriptional template for the virusHBV Life CyclecccDNA produce - four major RNA species;3.5 kb transcripts HBcAg or nucleocapsid protein from pgRNA HBeAg from pre core m RNAPol protein from pgRNA2.4 kb & 2.1 Kb transcripts - large surface proteins and middle surface HBsAg or envelop proteins 0.7 kb - HBX protein

Viral Life CycleRNA transcript - HBV polymerase - HBV core proteins. Reverse transcriptase (RT) enzyme (HBV polymerase) - a new viral DNA genome. Enclosed in the HB surface antigen (HBsAg) - as an intact virion. The viral particles are released from the host cells into the tissue and blood stream.Viral Life Cycle

Variability-Sources of Escape MutantsSerum HBV DNA - reliable indicator of active infection & hepatitis B surface antigen (HBsAg) - marker of chronic hepatitis B carriage,BUTThere is a substantial variability in HBV replicative activity that causes initiation of following stages in hepatitis B infection;Stage 1: Immune toleranceStage 2: Immune active/immune clearanceStage 3: Inactive chronic infectionStage 4: Chronic diseaseStage5: Recovery

Variability-Sources of Escape MutantsThe evolution of viruses due to High mutation rateVery short replication timesGeneration of large population of progeny particles&Interventions of HBIg & vaccinationTreatment with nucleoside/nucleotide analogues (Nas)Effect of Anti Viral DrugsAntihepadnaviral, Reverse Transcriptase inhibitorsAntiviral agents interfere with viral replication and weaken or abolish viral activity.

Tenofovir Disoproxil Fumarate (Viread)Entecavir (Baraclude)Lamivudine (Epivir)Adefovir Dipivoxil (Hepsera)Telbivudine (Tyzeka)

Variability-Sources of Escape MutantsVariability in HBV MutantsHBV genome, the reproduction by HBV RT (polymerase). The RT activity of the HBV polymerase enzyme does not have proof-reading abilityResult in frequent mistakes - can be as high as 1011viral particles per day. This error rate is high (1 per 100 bases)3200 nucleotides - 107errors per day. Individuals with chronic diseases often have 108to 1011HBV viral particles/mL per day. HBV Mutants Effecting Detection and VaccinationHBV Mutations Associated With Disease ProgressionMutations Associated With Drug ResistanceVaccine & Diagnostic MutantsVaccine EscapeHBsAg Assay EscapePrecore (PC)Basal Core Promoter (BCP)Gly145ArgThr 126 SerGly1896AlaAla1762ThrAsp144AlaGln 129 HisCys1858ThrGly1764AlaInsertion of Asn-Ser-Thr-Gly-Pro-Cys-Thr-Thr between Thr-123 and Cys-124Met 133 LeuThr1753CysAsp144AlaAla1762 ThrGly145ArgGly1764AlaHBsAg Mutants Associated With Antiviral Resistance

LamivudineAntiviral AgentsTelbivudineEntecavirEmtricitabineAdefovirTenofovirMet204ValMet204ValMet204IleMet204IleMet204IleAla181ValAla181ValAla181ValAla181ValAla181ThrAla181ThrAla181ThrAla181ThrSer202IleSer202IleSer202GlySer202GlyAsn236ThrAsn236ThrVal173LeuThr184Als/Phe/Met/Cys/Ser/Gly/Ile/LeuAla194ThrMet204SerMet250Val/Ile/LeuLeu180MetSer202CysHBV Genotypes

Ten HBV genotypes (i.e. A-J) have been identified so far, many of them include subgenotypes (adding up to 24).No subgenotypes have been described for genotypes E and G.Genotype distribution varies according to geographical area and ethnicity. Genotype A is frequent in northern Europe as well as in high HBV infection prevalence areas, such as northern Italy. It is also present in the USA, Argentina and in the Indian subcontinent. Genotypes B and C are found in China and Japan, whereas Genotype D is prevalent in eastern Europe. Genotypes E and F are found in the Western Africa, Southern USA, Central and South America and Central Europe. Regarding the ethnic factor, whereas genotype F is prevalent in Buenos Aires, Argentina, Rosario, a city 150 miles north from Buenos Aires with highly prevalent Italian immigration shows preponderance of genotype A.

HBV Genotypes

Interestingly, HBV infection can be caused by more than one genotype, suggesting a failure of the adaptive immunity in these cases. In addition, HBV genotype C, compared to genotype B, is associated with a higher frequency of core promoter mutation, and a lower response rate to interferon alfa therapy. Severity of HBV according to genotype finds an example in genotype C associated both, with low spontaneous HBeAg seroconversion, and with severe liver deterioration. Moreover, genotype C (along with D) shows a lower rate of IFN-induced-HBe-seroconversion compared with that of genotypes A and B. Likewise, a recent report shows that genotype B is not only associated with higher rate of spontaneous HBeAg seroconversion but also with lower rates of HCC. In Alaska, 1536 HBV infected patients after 20 years of follow-up show that genotypes C and F entail a higher risk of HCC.

Hepatitis B - DiagnosisThe physical examination:findings vary from minimal to impressive according to the stage of disease.

Routine Lab Investigation used to assess various stages of hepatitis B disease:ALATAlkaline PhosphataseGamma-GTTotal and direct serum bilirubin levelsAlbumin levelBlood CBC, Coagulation Studies ESR

Hepatitis B - DiagnosisSerologic testsHBsAgHBeAganti-HBcanti-HBc IgManti-HBc IgGanti-HBeViral Load or hepatitis B virus (HBV-DNA)

Hepatitis B - DiagnosisTable 1. Most common hepatitis B serological profilesHBsAgTotal Anti-HBcAnti-HBc IgMAnti-HBsInterpretationNEGNEGNEGNEGSusceptible to infectionPOSPOSPOSNEGAcute infection; acute exacerbation and re-activation of chronic infectionNEGPOSPOSPOS/NEGResolving acute infection; found in fulminant hepatitis BNEGPOSNEGPOSResolved past infectionPOSPOSNEGNEGChronic infection. Evaluate the presence of HBeAg, anti-HBe and levels of HBV DNANEGNEGNEGPOSImmune if >10 UI/ml, passive transfer of immunity by gamma globulin administration. Post-vacunationHepatitis B - DiagnosisTable 2. Uncommon HBV-related serological profilesHBsAgTotal anti-HBcAnti-HBc IgMAnti-HBsInterpretationPOSPOSNEGPOSCo-existence of HBsAg and anti-HBs

May be because of immune complexes; unspecific. It is recommended to evaluate quantitative HBV DNANEGPOSNEGNEGIsolated anti-HBc

Resolved past infection, HBsAg mutants, occult hepatitis B infection. Evaluate with anti-HBe quantitative HBV DNAPOSNEGNEGNEGEarly acute infection; transient antigenaemia after vaccination, immune tolerance, defective mutants and immunosuppressed patients.

Evaluate HBeAg and quantitative HBV DNAHepatitis B - DiagnosisTable 6. Different laboratory variables with an impact on eligible candidates for treatment according to international guidelinesGuideline/HBeAg+/HBeAgHBV VL (copies/ml)ALT (IU/L)AASLDHBeAg+>105>2x NVHBeAg>105>2x NVEASLHBeAg+>104>NVHBeAg>104>NVAPASLHBeAg+>105>2x NVHBeAg>104>2x NVHepatitis B - DiagnosisAssay TypeNameUseHBV antigenHBs AntigenDetected in active HBV infectionHBe AntigenDetected during high level of HBV replicationHBV antibodyAnti-HBsDetected in immune individuals due to immunization and/or infectionAnti-HBcIgMDetected in a new HB infectionAnti-HBc totalDetected in individuals with a current HBV infection or past infectionAnti-HBe totalDetected after recovery from an acute infectionHBV molecularQuantitative HBV DNADetected in an early HBV infection and used to monitor HBV-infected patients during antiviral treatmentHepatitis B - Diagnosis

Hepatitis B - Diagnosis

Hepatitis B - DiagnosisImaging studiesAbdominal ultrasonographyAbdominal computed tomography (CT) scanningAbdominal magnetic resonance imaging (MRI)ProceduresLiver biopsy, percutaneous or laparoscopic, is the standard procedure to assess the severity of disease in patients with features of chronic active liver disease (ie, abnormal ALAT & detectable levels of HBV DNA).

LiverLiver is the master organMain functions includeMetabolic activityExcretory ActivityProtective ActivityHematological ActivityStorage ActivityDamage to cells cause malfunctionLiver - Anatomy

Liver Anatomy & Histology

Liver - DiseasesViral HepatitisChronic HepatitisAlcoholic Liver DiseaseAlcoholic HepatitisCirrhosisHepato Cellular FailureInfections & InfestationsPrimary CarcinomaSecondary CarcinomaLiver - CHB

Liver - Cirrhosis

Liver - HCC

Liver Hepatitis & Complication

Grading Liver Cancer 0 = no inflammation 1-4 = minimal inflammation 5-8 = mild inflammation 9-12 = moderate inflammation 13-18 = marked inflammationGrading Liver Cancer 0 = no fibrosis or scarring 1 = minimal scarring 2 = scarring has occurred and is outside the areas of the liver which include blood vessels 3 = bridging fibrosis (the fibrosis is spreading and connecting to other areasthat contain fibrosis) 4 = cirrhosis or advanced severe scarring of the liver

Liver Biopsy Sampling errorPoor patient complianceLimited usefulness for dynamic follow-upRisk of complications typical of invasive procedures (Pain, bleeding, mortality)Sampling errorssampling error is common because only 1/50,000 of the organ is analyzedConsequenceThese limitations may lead to an underestimation of cirrhosis, especially when LB specimens are small or fragmented

We need a Test to be more representative of liverAnd less invasive

Non Invasive MarkerLiver biopsy is still the gold standard for liver histological assessment. It is mainly used both to assess the degree of hepatic inflammation and fibrosis and to rule out any other, co-existing liver disease. When performed by expert hands, this procedure ensures a very low rate of complications. Furthermore, the size of the specimen is really important, as far as the sample error is quite high (>35%) for specimens smaller than 1.5 cm.

ElastographyAlthough liver biopsy is still important for staging HBV disease, the advent of elastography has been regarded as a convenient alternative method in advanced stages of the disease. Its diagnostic accuracy for assessment of liver fibrosis has been demonstrated in patients with chronic viral hepatitis.It is important to keep in mind that although transient elastography cannot completely abolish the need for liver biopsy, it can be used as an important non-invasive method which enables us to tailor a more efficient strategy for managing patients with chronic hepatitis B.

ElastographyElastographyis amedicl imagingmodality that maps the elastic properties of soft tissue. The main idea is that whether the tissue is hard or soft will give diagnostic information about the presence or status of disease. For example,canceroustumours will often be harder than the surrounding tissue, and diseasedliverare stiffer than healthy ones.Elastography is a relatively new technology, and entered the clinic primarily in the last decade. Elastography