Transcript Hepatitis B - Steve's Homepage

Hepatitis B
Steve Hart
Electron
micrograph of
serum
containing
hepatitis B virus
after negative
staining.
Overview

Discussion Hepatitis B
Epidemiology
 Serologies
 Clinical course
 Prevention
 Treatment options
 Herbs

Hepatitis B
– Hepadnaviridae family
– DNA virus
– Double-shelled particles
– Outer lipoprotein
envelope (surface Ag)
– Inner viral nucleocapsid
(core)
– seven genotypes
– four major subtypes.
– All HBV subtypes share one
common antigenic
determinant - "a.“
– Thus, antibodies to the "a"
determinant confer protection
to all HBV subtypes
Diagrammatic
representation
of the hepatitis B
virion and the
surface antigen
components
EM of Hepatitis
B viron
Hep B epidemiology



1/3 of world’s
population has
been infected
350 million with
chronic disease
15-25% of these
die due to liver
related diseases


1 million deaths
annually
United States


1.25 million
chronic carriers
5000 deaths
annually
Hep B surface Ag prevalence, 2002
Source: CDC website
Hepatitis B transmission

Dominant mode of transmission related to
prevalence

Low prevalence (.1 to <2%) –adults
• unprotected sexual intercourse
• intravenous drug use

Moderate (3-5%) - children
• Horizontal transmission

High prevalence (>10-20%) - infants
• Maternal infant
• Percutaneous

Other


Occupational exposure
Blood transfusions
• Increasingly rare
Hepatitis B primary
infection

Symptoms


Can be asymptomatic


More common in
children
Usually self limited – in adults



Malaise, fatigue,
anorexia, nausea, low
grade fever after 45160 day incubation
Viral clearance from blood and liver
Lasting immunity
Can result in fulminate hepatic failure
Hepatitis B primary
infection
HBsAg 4-10 wks
 Anti-HBc
antibody follows
 +/- HBeAg
 Viral load very
high

109 to 1010
 Highly contagious
at this time

Hepatitis B primary
infection



Decrease in HBsAg
correlates with onset of
T-cell mediated
immune response
Also, when present,
correlates with onset of
elevated liver enzymes
Traditionally,
conversion to anti-HBs
antibodies signals cure

Viral DNA may persist for
years to lifetime
• Significance unknown
Hep B - Persistent Infection

Definition:

Persistence of HBsAg for greater
than 6 months
Hepatitis B persistent
infection


Persistent viral load that
declines over time
HBeAg declines overtime,
converting eventually to
anti-HBe antibody
• Seroconversion correlates
with rise in LFTs and 5
order of magnitude
decline in viral load.
• Classically, to Anti-HBe
antibody = no viral DNA
circulating, which is
incorrect

0.5% clear HBsAg
annually
Persistent Hepatitis B

Two clinical patterns

Chronic liver disease
• Elevated LFTS
• Abnormal hepatic histology
• 20% develop cirrhosis

Asymptomatic carrier
• Normal LFTs
• Asymptomatic
• Near normal liver histology

Both risk development of Hepatocellular
Carcinoma
Persistent Hepatitis B

HBV replication
extensive and
continuous in chronic
carriers


Replication is not
cytotoxic
Host immune
response to viral
antigens expressed
on infected
hepatocytes
Hepatocellular carcinoma
100 times the risk in persistently
infected patients
 Risk is greater if HBeAg positive
 Twice a year screening is recommended
in persistent carriers

• Alpha fetoprotein and/or hepatic U/S
• When to start screening is unclear
Who gets chronic disease?

Rule of thumb, the younger the age,
the more likely to become chronic
Neonates – 95% chronic, most
asymptomatic
 Infant to 6 yo – 30% chronic
 Older children to adults 3-5% chronic

Hepatitis B - Serology

Surface Antigen (HBsAg)

Hep B surface antigen Outer surface
lipoprotein, appears early
• Hallmark of infection
• Surface antigen antibody (anti-HBs)
signifies cure

Hep B core antigen (HBcAg)
•
•
•
•
intracellular antigen
expressed in infected hepatocytes
not detectable in serum
Core antibody appear early in
infection (Anti-HBc)
• Predominately IGM early in infection
• detection of IgM anti-HBc usually
regarded as an indication of acute
HBV infection
• Traditionally, the sole marker of HBV
infection during the window period
between the disappearance of HBsAg
and the appearance of anti-HBs
Hep B – e antigen



secretory protein that is processed from the
precore protein
Elevated early in infection and usually coverts
to antibody early on.
Traditionally used as a marker for viral load as
viral load was undetectable with early assays
when Ag was absent.
• However, certain variants of the Hep B virus do not
create the HBeAg as it has no known function.

When present, it does correlate with elevated
viral load and seroconversion the antibody
usually correlates with a decrease in viral load
by a magnitude of 4-5.
Hep B – serology
interpretation

Acute infection


HBsAg positive and anti-HBcAg
IGM
Rarely, IgM anti-HBc only marker
• Usually seen in acute fulminate
Hep B

Chronic infection


HBsAg positive and anti-HBcAg
Previous Infection



HBsAg negative
anti-HBs positive
IgG anti-HBc positive
Screening – Who?

Who




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
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Persons born in hyperendemic areas
Men who have sex with men
Injection drug users
Patients on dialysis
HIV infected patients
Pregnant women
Family and household contacts and sexual
contacts of HBV-infected persons.
Testing should be performed by obtaining
an HBsAg and anti-HBs.
Hepatitis B Treatments

Prevention
Neonates
 Vaccine


Prophylaxis


Possible exposure
Chronic infection
Prevention

In 1991, US started routine
vaccination
Since then incidence of acute HBV
infection has declined by 67%
 However, incidence has continued to
increase in adults

• Offer vaccine to high risk individuals
Prophylaxis


Hepatitis B immune globulin (HBIG) and
vaccine
Indications

Patients with no history of vaccine and
• Percutaneous exposure (needle sticks)
• Household contacts exposed to blood

Perinatal exposure – prevents transmission in
95% of mothers HBsAg positive when given
within 12 hours of birth
• Breast feeding ok if baby received prophylaxis
Treatment of persistent infectionWho to treat?

Treat:



HBeAg positive with
persistent infection
No treatment:

HBeAg negative and
carrier (nl LFTs, viral load
less than 105 and
asymptomatic)
Probably treat:

HBeAg
HBeAg negative with
chronic infection (high
viral load, abnormal LFTs)
Pos
Neg
Chronic
dz
treat
Probably
treat
Carrier
treat
Probably
not treat
Treatment options

FDA approved



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Interferon Alfa
Lamivudine – reverse transcriptase inhibitor
Adefovir – nucleotide analogue that inhibits
viral polymerase
Investigational

Tenofovir – adenine nucleotide analogue
• Approved for HIV

Entecavir – guanosine analogue, highly
selective for the HBV polymerase
Interferon alfa

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Had been mainstay for therapy
Subcutaneous injection three times per
week for 3 months or longer
30% of patients who could tolerated
regime had a successful response


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Seroconverted to HBe antibodies
Normalization of LFTs
Multiple side effects

Fever, myalgia, thrombocytopenia, depression
Interferon alfa

Contraindicated in very advanced
liver disease
‘Flairs’ or bump in LFTs occur at time of
seroconversion to anti-Hbe due to
increased immune response
 may precipiate overt liver failure
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Lamivudine
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Oral medication
Usually given for year or longer
Found to inhibit HIV reverse
transcriptase.

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Noted that patients with both HIV and chronic
Hep B had large declines in Hep B viral load
This phenomenon was then noted in patients
with only chronic Hep B
By itself, results in a 3 to 4 log decrease
serum viral load
Increased rate of seroconversion to HBeantibodies and normalization of LFTs
Lamivudine

Those who respond best are those with
elevated LFTs
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>5 times normal -> 65% response rate
2-5 times normal -> 26% response
<2 times normal -> 5% response
Remember, liver damage is caused by
immune response
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
So higher LFTs likely correlates to a most
robust host immune response
By inhibiting viral reproduction, the immune
system is able to clear the virus more
effectively.
Lamivudine

Use limited by resistance

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At one year of treatment 15-20% of patients
develop resistance
40% at two years
67% at four years
However, the resistant virus is less hearty
than the native virus resulting is lower
replication rates than pretreatment
Resistant variants also convert to antiHBe antibodies at higher rates.
Lamivudine

Resistance
No clear evidence regarding
continuation of treatment
 Prior to new meds, many continued.

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Discontinuing medication is
associated with flairs

Overlapping with another medication
recommended
Adefovir
Initially, devoloped for HIV
 Nucleotide analogue
 Prodrug phosphorylated
intracellularly to yield active drug
 Inhibits viral polymerase
 Has been evaluated for primary
monotherapy and in patients with
resistance to Lamivudine

Adefovir
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Efficacy
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Reduces viral load by 3 to 4 log
Enhances HBeAg seroconversion
Results in histological improvement of liver
Improved LFTs
Effective even in Lamivudine resistant patients
Much lower rate of resistance than
Lamivudine
Approach to treatment

Unfortunately, studies are lacking to
define what is the best approach

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Presently, alpa interferon, Adefovir and
Lamivudine are all considered first line
therapy
Considerations
•
•
•
•
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Adefovir – less resistance, possibly nephrotoxic
Lamivudine – good side effect profile
Interferon – difficult course
All provided about the same results
Unknown if benefit to using combination
therapy.
Hepatitis B/C Alternative Therapy:
What your patient might read about on the
internet

MTH-68/B. vaccine strain of
Newcastle disease, virus that
causes a bird infection
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Controlled study - conventional
tx’ment vs vaccine in acute phase
n=42, showed more progressed
to chronic infection with
conventional tx’mt.
Case reports of benefit to pts
given this vaccines after
progressing to decompensated
liver failure.
Both studies
investigated
the use in
both Hepatitis
B and C.
Hepatitis B and Herbs –
Cochrane review

Asymptomatic carries
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Very few quality studies
Three randomised clinical trials of carriers (307 patients) three
months or more of follow identified.
The methodological quality was poor overall, only one significant
trial
'Jianpi Wenshen recipe'
• significant effects on viral markers compared to interferon serum:
•
HBsAg,HBeAg, and seroconversion of HBeAg to anti-HBe.
• Poor long term f/u
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Chronic carriers

Fuzheng Jiedu Tang (compound of herbs)
• positive effects on clearance of serum HBsAg, HBeAg, and HBV DNA
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Polyporus umbellatus polysaccharide vs interferon
• Positive effects on serum HBeAg and HBV DNA

Phyllanthus amarus vs interferon
• Improvement in serum HBeAg
Hepatitis B Alternative Therapies

One small retrospective study showed patients in
fulminent hepatic failure who took dietary or herbal
supplements often did worse than those who did not.
Surg. 2003 Aug;138(8):852-8.
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Thought to be due to heptotoxic effects of componds in these
supplements.
Basically –
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
Arch
No firm evidence supporting medicinal herbs
follow-up randomized trials seem justified for some
Would not recommend due to potential hepatotoxic effects
References
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Images:
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http://www.cdc.gov/ncidod/diseases/hepatitis/

http://gsbs.utmb.edu/microbook/ch070.htm
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http://web.uct.ac.za/depts/mmi/jmoodie/dihep.html
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http://www.aids-hepatitisc.org/healthinsurance/maps-graphs/figure7-infectious-hepatitis.gif
Am J Gastroenterol. 2003 Mar;98(3):538-44
Arch Surg. 2003 Aug;138(8):852-8
N Engl J Med Mar 11,2004;
Pediatrics in Review, Vol 24, No.12 Dec 2003