Page 442 - Concise Pathology for Exam Preparation ( PDFDrive )

15 Diseases of the Hepatobiliary System and Pancreas 427

• Another soluble antigen in the nucleocapsid is called hepatitis B e-antigen or
HBeAg)
• A DNA polymerase enzyme (pol) that exhibits reverse transcriptase activity
• A protein from the X region, HBX necessary for viral replication; HBX controls
gene transcription and thus acts as a gatekeeper for hepatocyte check points in cell
cycle.
• The corresponding antibodies are
• Anti-HBs
• Anti-HBc
• Anti-HBe
Serological diagnosis (Fig. 15.2):
• Serum HBsAg is the first serum virological marker to appear. It appears in the later
part of the incubation period or in the early prodrome of hepatitis B. Peak levels
are reached during acute disease and the levels decline to undetectable levels in
3–6 months. Antibody to HBsAg is detected in the serum after HBsAg disappears.
• HBeAg, HBV–DNA and DNA polymerase are detected in the serum immediately after
the appearance of HBsAg. Their presence indicates active viral replication.
• IgM anti-HBc appears in serum just before the patient manifests with acute disease (it
is the earliest antibody to appear and is replaced by IgG anti-HBc over a period of few
months.
• Persistence of detectable HBsAg beyond 6 months suggests chronic hepatitis B infection.
In such cases, anti-HBs becomes negative but anti-HBc remains detectable.
• Indicators of chronic replication:
• Persistence of circulating HBsAg, HBeAg and HBV DNA
• Presence of anti-HBc and occasionally with anti-HBs
Epidemiology
• Incubation period is about 1–4 months.
• Asymptomatic carriers or persons with acute hepatitis or chronic liver disease are the
source of infection. It is present in all body fluids except stool.
• The main route of transmission of Hepatitis B is parenteral (commonly occurs after
transfusion of infected blood or blood products, injections with contaminated nee-
dles, dialysis, tattooing and acupuncture). It spreads through body fluids like saliva,
urine, semen and vaginal secretions.
• Mother-to-child spread (vertical or perinatal transmission) is also common.
• High-risk groups include spouses of persons having acute infection, homosexuals,
healthcare workers, dentists and haemophiliacs.
• The incidence of a chronic carrier state in HBV infection varies between 1% and 20%.

Incubation
period
30–180 days
DNA polymerase HBe Ag Core window
(3–6 weeks)
HBs Ag (6 weeks) IgM anti-HBc Anti-HBe IgG anti-HBc (20 weeks)
Anti-HBs
(4 weeks)

(12 weeks)
Level (6 weeks)
0 4 8 12 16 20 24 Years
FIGURE 15.2. Serological diagnosis of hepatitis B.

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