Download - Antibody - Viral Tests[1]
-
7/31/2019 Antibody - Viral Tests[1]
1/3
HBVHepatitis B Fact SheetHepatitis B Fact Sheet
a series of fact sheets written by experts in the field of liver disease
A Publication of the Hepatitis C Support Project
www.hbvadvocate.org
How to Interpret Hepatitis B
Antibody & Viral Tests
Written by: Chistine M. Kukka HBV Project Manager
To determine i someone is inected with the hepatitis B virus (HBV), or
to nd out the status o an inection, a clinician will take a blood sample
and send it to a laboratory. Technicians will analyze it or several hepatitis
B viral components, which provide a roadmap to an inection.
These viral components include antigens or proteins that make up dier-
nt parts o the virus and antibodies, which the immune system gener-
ates to combat each antigen. A viral test is dierent than a liver unction
est, which also requires a blood sample. Liver unction tests look at liver
nzymes, such as alanine aminotranserase or ALT, and other substances
hat may indicate i the liver is healthy or damaged.
Up to 70 percent o people inected with HBV, especially children, experi-nce no symptoms. The most common symptoms are jaundice (yellowing
the skin or the whites o the eyes), atigue, stomach discomort and ab-
dominal pain, ever, loss o appetite, nausea and joint pain.
Hepatitis B Antigens include:
Surface antigen:The outer coating o the virus is made up o the sur-
ace antigen or HBsAg. It surrounds the core o the virus.
Core antigen: The inner shell o a virus contains the core antigen (HB-
Ag). This antigen is only ound in inected liver cells.
E antigen: Another antigen ound in the cores interior is the e antigen
HBeAg).
To resolve or clear the HBV infection, the immune system must
produce antibodies against the HBV antigens certain proteins
of the hepatitis B virus.
HBV Genotype:
There are dierent strain
or genotypes o HBV
Each genotype originate
in dierent regions o th
world and is designate
by letters A-H. Doctor
dont routinely conduc
genotype tests, whic
require a blood sample
However, i pegylated in
tereron treatment is bein
considered, a doctor ma
order a genotype test be
cause genotypes A and B
appear to respond bette
to intereron than geno
types C and D.
-
7/31/2019 Antibody - Viral Tests[1]
2/3www.hbvadvocate.org
Hepatitis B Fact SheetHepatitis B Fact Sheet Fact SeriesHBV
Antibody & Viral Tests
Also within the core o the virus
are the viral DNA genetic mate-
ial and the DNA polymerase en-
zyme, which contains the key ge-
netic replication instructions.
n order to diagnose hepatitis B,
certain markers such as surace
antigens and antibodies, the e
antigens and antibodies, and core
antibodies are measured in a viral
est. Also, the levels o virus in the
blood (hepatitis B DNA or HBV
DNA) are measured to track how
actively viruses are replicating.
Hepatitis B surface antigen (HB-
sAg): The presence o surace
antigen in a lab report indicates
a hepatitis B inection. It can be
an acute (short-term) or a chronic
potentially lie-long) inection.
Simply put, i the surace antigen
s present, a person has HBV and
s capable o inecting others.
When HBV replicates in the liver,
t produces more surace antigen
han is needed to generate new
viruses. These excess surace
antigens clump together in the
bloodstream and are easily iden-
ed by lab tests. Laboratory
ests can usually identiy suraceantigen about our weeks ater in-
ection, but it can take as long as
nine weeks.
n an acute inection, the immune
system is able to combat the or-
eign surace antigen by creating
enough surace antibodies (ab-
breviated HBsAb or anti-HBsAg)
to destroy this antigen within a
ew weeks o when symptoms rst
appear. However, in a chronic in-
ection, the immune system can-
not eectively rid the body o the
antigen and create enough an-tibodies to ght o the inection.
Chronic hepatitis B is diagnosed
when surace antigen is present
in the bloodstream or more than
six months.
When surace antigens disappear
and surace antibodies appear in
a lab report, then a person has
cleared the inection. Bottom
line:the surface antibody is what
everyone wants to develop. It
means they have cleared the in-
fection and can no longer infect
others.
Hepatitis B Core Antigen (HB-
cAg) and Antibodies (anti-HBc
or HBcAb): The hepatitis B coreantigen orms the inner core o
the virus and is produced when
the virus replicates in liver cells.
The core antigen is ound only in
HBV-inected liver cells, not in the
bloodstream. But core antibodies
are ound in the bloodstream and
are identied by viral tests.
Core antibodies are the rst de-
tectable HBV antibodies to ap-
pear, usually within a ew weeks
ater inection. They are present in
anyone who has had either acute
or chronic HBV inection.
People who have been vaccinat-
ed against hepatitis B have been
injected with only the surace
tigen portion o the virus, to ca
their immune systems to prod
surace antibodies to pro
them against uture inection.
viral test on their blood would o
reveal the surace antibody. Hever, anyone who has been a
ally inected with HBV would h
core antibodies as well as sur
antibodies in their lab test.
Hepatitis B e Antigen (HBe
and e Antibodies (anti-Hbe
HBeAb): The e antigen is a
tein secreted by hepatitis B vi
es that are actively replicatingliver cells. When a lab test ide
es the e antigen, it means
virus is actively replicating and
person usually has a large qua
o HBV-DNA in their bloodstre
Their blood and body fuids
usually more inectious, beca
o the high volume o virus, t
someone who has developed
e antibody.
People with the e antigen m
be at greater risk o progress
to liver disease than those w
have developed the e antibo
especially ater many years
inection, because it indica
rapid viral replication. Child
with chronic hepatitis B otest positive or the e anti
because their immune syste
have not yet noticed the viru
attacked the inected liver ce
Some people who have had h
atitis B or many years lose the
-
7/31/2019 Antibody - Viral Tests[1]
3/3
2010 Hepatitis C Support Pro
www.hbvadvocate.org
The inormation in this act sheet is designed to help you understand and man-
age HBV and is not intended as medical advice. All persons with HBV should
consult a medical practitioner or diagnosis and treatment o HBV.
Executive Director,Editor-in-Chief, HCSP Publications
Alan Franciscus
Managing Editor / WebmasterC.D. Mazoff, PhD
This inormation is provided by the Hepatitis C Support Project a nonproft organization or HCV education, support and advocacy.
Reprint permission is granted and encouraged with credit to the Hepatitis C Support Project.
Hepatitis B Fact SheetHepatitis B Fact Sheet Fact SeriesHBV
For more inormation about hepatitis B, visit the ollowing websites.
Hepatitis B Foundation: www.hepb.org HIVandHepatitis.com
HCSP VERSION 3.0 September 20
antigen, developeantibodies,
but continue to have moderate-
y high viral load and elevated
ALT levels, which indicates liver
damage. This HBeAg-nega-
ive hepatitis is believed to be
caused by HBV that have cer-
ain mutations (a precore mu-
ation), which allow the virus to
eplicate without producing the
e antigen.
n acute hepatitis B, when the
bodys immune system quickly
esponds and eradicates theantigens and inected liver
cells, the e antigen appears
only briely. It disappears as
viral replication declines in the
ver and the immune system
produces e antibodies to de-
stroy this antigen.
Hepatitis B e antibodies usu-
ally persist or one or more years
ater resolution o an acute in-
ection. Seroconversion, or
production o e antibodies, is
one o the goals o most medi-
cal treatments or hepatitis B.
Once e antibodies are pro-
duced, there are usually ewer
HBV inecting and damaging
he liver.
Antibody & Viral Tests
Hepatitis B Virus DNA (HBV
DNA): HBV DNA is the genetic
material that carries the blue-
print o the virus. It is ound in
the bloodstream and is the best
indication o how rapidly thevirus is replicating in the liver.
High levels o HBV-DNA, which
can reach up to millions or bil-
lions o international units per
milliliter (abbreviated copies/
mL), indicate rapid viral replica-
tion in the liver and a higher risk
o liver damage. Low or unde-
tectable rates indicate low viral
replication in the liver.
Because viral load can be very
high, viral load can be reported
in logs that represent multi-
plying the number by 10, so 101
equals 10, 102 equals 100, and
103 equals 1,000 etc. A v
load that appears as 104 c
ies/mL equals 10,000 cop
mL.
Doctors should always tespatients viral load becaus
plays an important role in
ciding i someone needs tre
ment, or i treatment is work
to lower viral load. For ex
ple, current guidelines sugg
that people who test positive
HBeAg, have elevated ALT
els that indicate liver dama
and who have a viral load ab
20,000 IU/mL may be con
ered or treatment. Peo
who are HBeAg-negative w
elevated ALTs, and who h
viral load exceeding 2,000
mL may also be considered
treatment.
Some people who have
had hepatitis B for many
years lose the e antigen,
developeantibodies, but
continue to have moderately
high viral load and elevated
ALT levels, which indicates
liver damage.