Download Hepatitis B – Laboratory Tests

In The Name of God
Dr Mostafa Javanian
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A HCW Presented with icter and fever, one
month after Needle stick with a known case
of chronic HBV infection.
The laboratory finding were as follow:
Medical university of Babol
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ALT=4100 IU/l
AST=3600 IU/l
ALK =500 IU/l
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Bill
T:
D:
10mg/dl
6mg/dl
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HBS Ag :positive
Anti HBC IgM : positive
HBe Ag : positive
HBs Ab : negative
Anti HCV : negative
Anti HAV IgM : negative
HIV ELISA : negative
Medical university of Babol
Medical university of Babol
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Serology:
◦ Many tests available – most common tests are
Enzyme Immunoassays (EIAs, MEIAs)
◦ First tests available in 1972
◦ For every rule, there is an exception/caveat
◦ No single test tells you everything
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Molecular:
◦ HBV DNA (quantitative)
◦ HBV genotyping
◦ HBV resistance testing
Medical university of Babol
Hepatitis B – Laboratory Tests
Serologic markers:
1) HBsAg (Hepatitis B surface antigen):
• if positive, person is infectious
• Sensitivity = 0.15 ng/ml
• Specificity = 99.5%
2) Anti-HBs (Antibody to HBV surface antigen):
• indicates immunity to HBV and protection from
disease
• Protective level is >10 IU/ml
Medical university of Babol
Hepatitis B – Laboratory Tests
Serologic markers:
3) Anti - HBc (Antibody to HBV core antigen):
• Total - indicates past or active infection;
present whether person is immune or chronic
carrier
• Specificity = 99.8% to 99.9%
• IgM - early indicator of acute infection
• No antigen test
Medical university of Babol
Hepatitis B – Laboratory Tests
Serologic markers:
4) HBeAg (Hepatitis Be antigen):
• indicates person is highly infectious
• Selecting patients for therapy
5) Anti-HBe (Antibody to HBVe antigen):
• prognostic for resolution of infection; less
infectious; spontaneous seroconversion in 10
to 20% of healthy adults per year
Medical university of Babol
Serologic markers – caveats:
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Persistent HBsAg for >6 mos = chronic
infection
HBsAg and anti-HBs may co-exist in some of
chronically infected individuals; likely due to
mutations in the “a” determinant of the S
gene
◦ Surface antigen escape mutants described in
infants infected with HBV after HBIG + vaccination
and in Liver transplants after prolonged HBIG
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Anti-HBc IgM may persist for up to 2 years
in 20%; chronically infected individuals may
have low titres which rise during acute flares
Medical university of Babol
Serologic markers – caveats:
 Precore or HBeAg negative mutants:
◦ Due to mutation in precore (abolishes HBeAg
production) or core promoter region (down-regulates
HBeAg production)
◦ No effect on viral replication (may be enhanced)
◦ More difficult to treat; greater risk of cirrhosis
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Co-infection with HCV may suppress both
HBeAg and HBsAg
Medical university of Babol
Serologic markers – caveats:
 Isolated HBcAb may be due to:
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Remote infection (immune or chronic carrier)
“Window” period between HBsAg and HBsAb
Co-infection with HCV
False positive test result – HBcAb is marker most
prone to false positives
HBV DNA may help sort this out
Medical university of Babol
Medical university of Babol
Phase
HBsAg HBeAg AntiHBe
ALT
HBV DNA
range
Immune
Tolerant
+
+
-
Normal
>8 log IU/mL
Immune
Clearance
+
+
-
Normal or
elevated
3-8 log IU/mL
Inactive
Disease
+
-
+
Normal
<3 log IU/mL
HBeAgnegative
Chronic
HBV
+
-
+
Normal or
elevated
3-8 log IU/mL
Medical university of Babol
Medical university of Babol
Serology:
 Detection of anti-HCV antibodies
 Serologic test available since 1990
Molecular:
 HCV RNA detection
 Determination of HCV genotype
 Viral load determination
Medical university of Babol
Serology:
 Screening:
◦ 3rd generation EIAs measure antibodies
directed against recombinant peptides NS4,
core, NS3, and NS5 proteins
◦ Sensitivity = 97%
◦ Detects antibodies within 6 to 8 weeks
◦ No HCV IgM test available
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Confirmatory/supplementary:
◦ RIBA, Second EIA, HCV RNA
Medical university of Babol
Molecular:
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Both qualitative and quantitative HCV RNA
assays available
Used for treatment monitoring (and in some
circumstances for confirmation of positive or
indeterminate serology)
HCV RNA is detectable 2 to 14 days after an
exposure
Medical university of Babol
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Used for:
◦ Detection of mutations that confer resistance to
antiviral agents
◦ Genotyping of isolates for epidemiological
purposes; categorizes patient isolates into 8
different HBV genotypes (A to H) and 6 different
HCV genotypes (1 to 6 with 24 subtypes)
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Methods include:
◦ Sequencing
◦ Hybridization (Line Probe Assay, Trugene Assay)
Medical university of Babol
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Serology remains the cornerstone for diagnosis
and screening
NAAT is critical to patient management
Of the many NAAT tests available, PCR, bDNA and TMA
remain most popular
◦ Sensitivity and dynamic range varies between assays
◦ Standardization allows (to some degree) interchangeability
of the results with different assays
Resistance/Genotyping requires amplification first
◦ Increasing role in making treatment decisions as more
drugs become available for HBV
Medical university of Babol
‫با تشکرفراوان ازتوجه شما‬