viral markers
DESCRIPTION
Viral Hepatitis Markers especially HBVTRANSCRIPT
Mohamed Sabry Ass. Lecturer of Internal Medicine
Tanta Faculty of Medicine
Serology for viral hepatitis (HAV, HBV & HCV)
Pathogenesis
Clinical presentation
Life cycle & Modes of transmission
Serology
Serology
Hepatitis B viurs
Serology
Hepatitis B viurs
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Hepatitis A virus:
Anti-hepatitis A virus IgM:
Positive at the time of onset of symptoms.Usually accompany the first rise in the alanine aminotransferase (ALT) level.
This test is sensitive and specific.The results remain positive for 3-6 months after the primary infection and for as long as 12 months in 25% of patients.
Anti-hepatitis A virus IgG:
Anti-HAV immunoglobulin G (IgG) appears soon after IgM and generally persists for many years.
The presence of anti-HAV IgG in the absence of IgM indicates past infection or vaccination rather than acute infection. IgG provides protective immunity.
HBV: Structure
HBV: virus proteins & particles:
HBV: Genomic structure:
Basics:
Deoxyribose nucleic acid (DNA) is the genetic material in all cells.
It is a double helix structure made of nucleotides.
Each nucleotide consists of a deoxyribose sugar, a phosphate group, and one of four bases: adenine, thymine, guanine and cytosine.
Protein products of the four genes
S gene: HBsAg S region: Major proteinS+preS2: Middle proteinS+preS2+preS1:Large protein
P gene: DNA polymerase
Directs replication and repair of HBV DNA
C gene: HBcAg
HBeAg
Translation begins with the C region.Translation begins at the preC region
X gene: HBxAg It can transactivate transcription of cellular and viral genesIt may contribute to carcinogenesis.
HBV: virus proteins & particles:
Protein products of the four genes
S gene: HBsAg S region: Major proteinS+preS2: Middle proteinS+preS2+preS1:Large protein
P gene: DNA polymerase
Directs replication and repair of HBV DNA
C gene: HBcAg
HBeAg
Translation begins with the C region.Translation begins at the preC region
X gene: HBxAg It can transactivate transcription of cellular and viral genesIt may contribute to carcinogenesis.
Viral proteins & particles:
Serology for HBV:
Antigen AntibodiesHepatitis B Surface Antigen (HBsAg)
Antibody to Hepatitis B Surface Antigen (Anti HBs)
Hepatitis B Core Antigen (HBcAg)
Antibody to Hepatitis B Core Antigen (Anti HBc IgM & Anti HBc)
Hepatitis B ‘e’ Antigen (HBeAg)
Antibody to Hepatitis B ‘e’ Antigen (Anti HBe)
Hepatitis B surface antigen (HBsAg):
It is the envelop protein expressed on the outer surface of the virion and on the small spherical and tubular structures.
It plays a major role in cell membrane attachment to initiate the infection process by binding to the hepatocyte plasma membrane
C Seeger, et al. (2000): Mol Biol Rev.
HBsAgCommon
group reactive antigen (a).
Several subtype specific antigens (d, y,
w & r).
HB isolates fall into at least 8 genotypes (A-H).
Gen
otyp
es v
ary Antigenic subtype
Geographic Destribution
Clinical course
Exam
ples
genotype A (subtype adw) and genotype D (ayd)
Geographic Destribution
Clinical course
Exam
ples
genotype A (subtype adw) and genotype D (ayd)
genotype A & D predominate in USA and Europe and genotype B &
C predominate in Asia.
Clinical course
Exam
ples
genotype A (subtype adw) and genotype D (ayd)
genotype A & D predominate in USA and Europe and genotype B
& C predominate in Asia.
genotype B is associated with less aggressive liver damage and less HCC as compared to genotype C .
HBsAg
1st virological marker detectable in serum usually between 8th and 12th weeks of
infection
HBsAg
1st virological marker detectable in serum usually between 8th and 12th weeks of
infection
It preceeds elevation of aminotransferase activity and clinical symptoms by 2-6
weeks
HBsAg
1st virological marker detectable in serum usually between 8th and 12th weeks of
infection
It preceeds elevation of aminotransferase activity and clinical symptoms by 2-6
weeks
It remains elevated during the entire
icteric or symptomatic phase of the disease.
HBsAg
1st virological marker detectable in serum
usually between 8th and 12th weeks of infection
It preceeds elevation of aminotransferase
activity and clinical symptoms by 2-6 weeks
It remains elevated during the entire icteric or symptomatic phase
of the disease.
Typically, it disappeares 1-2 months after the onset of jaundice and
rarely persists beyond 6 months.
HBsAg
Strategies for prevention of
HBV is based on providing
susceptible persons with anti
HBs.
The protective antibodies
Anti HBs
Anti HBs
Duration of protection: almost
indefinitely. A single booster may be
required after 5 ys.
HBsAg prepared by recombinant DNA technology
HBV Vaccine
Not secreted and remains
within hepatocytes
Expressed on the surface of
the nucleocapsid
core
HBcAg
HBcAg
HBV: virus proteins & particles:
Anti HBc IgM
First antibody
to appear.
Indicates acute HBV
infection.
Anti HBcIgM
Anti HBcIgM
May be the only
marker in CORE
WINDOW
Indicates acute HBV
infection.
Anti HBcIgM
HBeAg
Secreted into the circulation.
HBeAgSecreted into the circulation. HBeAg
Accessory protein of HBV.
HBeAgSecreted into the circulation.
HBeAgAccessory protein of HBV.
HBeAg
Not essential for replication in vivo
An index of viral replication, infectivity, severity of disease, and response to treatment
An index of viral replication, infectivity, severity of disease, and response to treatment
HBeAg persists longer than 12 weeks: High probability of progression to a chronic carrier state when.
An index of viral replication, infectivity, severity of disease, and response to treatment
High probability of progression to a chronic carrier state when HBeAg persists longer than 12 weeks.
Pregnant women with HBeAg positive have a risk of transmission of virus to fetus is > 90%.
Anti HBe
Detectable when HBeAg disappears (12 – 16 wks)
Anti HBe
Seroconversion to Anti HBe indicates
resolution of infection.
Anti HBe
Seroconversion may be associated with acute hepatitis like elevation of aminotransferase.
Anti HBe
HBV: Precore mutation:
Basics
Mutations are sudden changes in an organisms genetic material that result from alterations in DNA that can be induced or appear spontaneously.
HBV: Genomic structure:
HBV: Precore mutation:
Patients with precore mutation tend to have severe liver disease that progress more rapidly to cirrhosis.
This is common in Mediteranean region and Europe.
Clusters of fulminant HBV in Israel and Japan have been attributed to a common source of infection with a precore mutant.
HBV DNA
A measure of virus replication in the liver and infectivity.
HBV DNA
Monitoring treatment in patients with chronic HBV infection.
HBV DNA
Loss of detectable HBV DNA is an earlier indicator of response to
antiviral therapy than loss of HBeAg.
HBsAg Anti-HBsAg
Anti-HBc HBeAg Anti-HBe Interpretation
+ - IgM + -
HBsAg Anti-HBsAg
Anti-HBc HBeAg Anti-HBe Interpretation
+ - IgM + - Acute HB, High infectivity
HBsAg Anti-HBsAg
Anti-HBc HBeAg Anti-HBe Interpretation
+ - IgM + - Acute HB, High infectivity
+ - IgG + -
HBsAg Anti-HBsAg
Anti-HBc HBeAg Anti-HBe Interpretation
+ - IgM + - Acute HB, High infectivity
+ - IgG + - Chronic HB, high infectivity
HBsAg Anti-HBsAg
Anti-HBc HBeAg Anti-HBe Interpretation
+ - IgM + - Acute HB, High infectivity
+ - IgG + - Chronic HB, high infectivity
+ - IgG - +
HBsAg Anti-HBsAg
Anti-HBc HBeAg Anti-HBe Interpretation
+ - IgM + - Acute HB, High infectivity
+ - IgG + - Chronic HB, high infectivity
+ - IgG - + Chronic HB, low infectivity
HBsAg Anti-HBsAg
Anti-HBc HBeAg Anti-HBe Interpretation
+ - IgM + - Acute HB, High infectivity
+ - IgG + - Chronic HB, high infectivity
+ - IgG - + HBeAg negative precore
mutant HB
HBsAg Anti-HBsAg
Anti-HBc HBeAg Anti-HBe Interpretation
+ - IgM + - Acute HB, High infectivity
+ - IgG + - Chronic HB, high infectivity
+ - IgG - + Chronic HB, low infectivity
HBeAg negative
precore mutant HB
+ + +
HBsAg Anti-HBsAg
Anti-HBc HBeAg Anti-HBe Interpretation
+ - IgM + - Acute HB, High infectivity
+ - IgG + - Chronic HB, high infectivity
+ - IgG - + Chronic HB, low infectivity
HBeAg negative
precore mutant HB
+ + +
HBsAg Anti-HBsAg
Anti-HBc HBeAg Anti-HBe Interpretation
+ - IgM + - Acute HB, High infectivity
+ - IgG + - Chronic HB, high infectivity
+ - IgG - + Chronic HB, low infectivity
HBeAg negative
precore mutant HB
+ + + + + HBsAg of one subtype and
heterotypic antiHBs
HBsAg Anti-HBs Anti-HBc
HBeAg Anti-HBe Interpretation
- - IgM + +
HBsAg Anti-HBs Anti-HBc
HBeAg Anti-HBe Interpretation
- - IgM + + Acute HB (window)
HBsAg Anti-HBs Anti-HBc
HBeAg Anti-HBe Interpretation
- - IgM + + Acute HB (window)
- - IgG - +
HBsAg Anti-HBs Anti-HBc
HBeAg Anti-HBe Interpretation
- - IgM + + Acute HB (window)
- - IgG - + HB in the remote past
HBsAg Anti-HBs Anti-HBc
HBeAg Anti-HBe Interpretation
- - IgM + + Acute HB (window)
- - IgG - + HB in the remote past
Low level HB carrier
- + IgG - +
HBsAg Anti-HBs Anti-HBc
HBeAg Anti-HBe Interpretation
- - IgM + + Acute HB (window)
- - IgG - + HB in the remote past
- + IgG - + Recovery from HB
HBsAg Anti-HBs Anti-HBc
HBeAg Anti-HBe Interpretation
- - IgM + + Acute HB (window)
- - IgG - + HB in the remote past
Low level HB carrier
- + IgG - + Recovery from HB
- + - - -
HBsAg Anti-HBs Anti-HBc
HBeAg Anti-HBe Interpretation
- - IgM + + Acute HB (window)
- - IgG - + HB in the remote past
Low level HB carrier
- + IgG - + Recovery from HB
- + - - - Immunization with HBsAg
False positive
HCV• HCV antibody:
• Generally used to diagnose hepatitis C infection.
• Not useful in the acute phase as it takes at least 4 weeks after infection before antibody appears.
HCV• HCV-RNA:
• Various techniques are available e.g. PCR. Cut-off: 1000 copies / ml
• May be used to diagnose HCV infection in the acute phase.
• However, its main use is in monitoring the response to antiviral therapy.
HCV RNA (PCR testing)
Not a predictor of disease severity: a high viral load does not mean the liver disease is more severe, and a low viral load does not mean the patient is ok and does not need therapy!
Helps predict response rate to treatment (lower means a higher chance of cure with therapy)
HCV:
Genotyping: genotype 1 and 4 have a worse prognosis overall and respond poorly to interferon therapy.
The END