21.
Considering HBV immunological assays, the first marker to appear during an
acute HBV infection is hepatitis B surface antigen (HBsAg). It can be detected in
the serum of infected patients during the incubation period. The presence of
HBsAg in serum indicates the possible presence of HBV and the potential
infectious state of that person. The presence of HBsAg beyond six months and
the failure of seroconversion to anti-HBs implies progression to the chronic carrier
state.
The HBeAg marker appears shortly after HBsAg and acts as an early indicator of
acute infection. It indicates that the virus is actively replicating and that the
individual is highly infectious.
Seroconversion from HBeAg to anti-HBe should occur during the acute phase and
is prognostic for resolution of the infection. The presence of anti-HBe is an
indicator of the patient's reduced infectious state. The failure to seroconvert to
anti-HBe and the continued presence of HBeAg beyond six months implies
progression to chronic carrier state.
Anti-HBc IgM is an IgM antibody produced in the initial response to hepatitis B
core antigen. It is an early marker of acute infection and is used to distinguish an
acute HBV infection from a chronic carrier state. Anti-HBc IgM is also used to
distinguish hepatitis B from non-A, non-B hepatitis.
Anti-HBc measures total antibody (IgM and IgG) to hepatitis B core antigen. It is a
lifelong marker and acts as an indicator of current or previous hepatitis B infection.
It does not appear to be associated with recovery from or immunity to hepatitis B.
The immunological marker anti-HBs does not appear during the acute phase of
the disease but rather during convalescence. Ant-HBs is not detectable in the
serum until HBsAg has disappeared and therefore acts as an indicator of recovery
and immunity. The "window period" is the gap of time between the disappearance
of the surface antigen and the appearance of anti-HBs. This antibody is the major
protective antibody against the virus and results from either past exposure to the
virus or as the result of successful vaccination.
(para 7-21)
MD0838
7-25
Previous Page
