immunodiagnosis of viral hepatitis students (1).ppt

Immuno-diagnosis of Viral
Hepatitis
Dr Muhammad Barkaat Hussain
MBBS, M.Phil Microbiology
PhD Microbiology
Assistant Professor Microbiology
King Abdul Aziz University, KSA

Learning Objectives
• List viruses that primarily infect the liver (hepatitis viruses)
• Describe the differences between these viruses as regard type of virus,
mode of transmission, prevalence, fulmination, chronicity, Oncogenicity
• Describe the different methods of prevention and control of these
viruses
• Describe the role of HBV and HCV in liver cirrhosis and HCC
• Identifies the main serological markers used in the diagnosis of types of
viral hepatitis
• Describe the importance of blood screening for the prevention of
transfusion-associated hepatitis and the types of tests routinely
performed in the blood bank
• Appreciate the importance of water and food hygiene in the prevention
of HAV and HEV

Clinical Scenerio
 A 20-year-old medical student presented
with loss of appetite, fever and yellowish
discoloration of both eyes.
 He told the doctor that he had a needle
prick injury approximately 4 months back
after drawing blood from a patient.

HIV
• The average risk of seroconversion after a needlestick
injury from a confirmed HIV source is approximately 0.3
percent without post-exposure therapy .
• Certain factors contribute to elevated risk:
• Increased depth of the puncture wound
• Visible blood on the needle
• Needle used in the vein or artery of the patient
• Patient with terminal HIV as source of the fluid

Hepatitis B Virus (HBV)
• The risk of acquiring hepatitis secondary to HBV
percutaneous exposure varies based on the serological
status of the patient.
• In the worst case scenario, if the patient has active
replication of the virus
• (indicated by HBeAg-positive blood then the risk of
developing clinical hepatitis is as high as 31 percent.
• When the patient has HBsAg-positive blood but is
HBeAg-negative (indicating a less infective state), the
risk is significantly lower, about 1 to 6 percent.

Hepatitis C Virus (HCV)
• The risk of HCV seroconversion after a needlestick injury
from a patient infected with HCV is approximately 1.8
percent .
• Unfortunately, there is little evidence to support
postexposure treatment as a means to decrease the risk
of infection

Investigations
 HBs antigen and anti-HBs antibodies
 Anti HCV antibodies
 HIV antibodies

Viral Hepatitis
• "Hepatitis" means inflammation of the liver and also
refers to a group of viral infections that affect the liver .
• The most common types are Hepatitis A, Hepatitis B,
and Hepatitis C.
• Viral hepatitis is the leading cause of liver cancer and the
most common reason for liver transplantation.
• An estimated 4.4 million Americans are living with
chronic hepatitis; most do not know they are infected.

Viral Hepatitis
• Hepatitis viruses A and E transmit by oral-
fecal route and will cure completely when
the victims survive.
• Hepatitis viruses B, C, and D transmit by
blood-borne route and may become
chronic hepatitis, and progress further to
cirrhosis and carcinoma.

• The hepatitis A virus is found in the stool of an
infected person.
• It is spread when a person eats food or drinks
water that has come in contact with infected
stool.
• Contaminated food, water
(e.g., infected food handlers, raw shellfish)
• Close personal contact
(e.g., household contact, child day care centers)
Hepatitis A Virus Transmission

Symptoms of Hepatitis
• All hepatitis viruses can cause acute hepatitis.
• Viral hepatitis types B and C can cause chronic
hepatitis.
• Symptoms of acute viral hepatitis include
• fatigue, loss of appetite flu-like symptoms, dark
urine, light-colored stools, fever and jaundice;
• however, acute viral hepatitis may occur with
minimal symptoms that go unrecognized.

 Incubation period: Average 30 days
Range 15-50 days
 Complications: Fulminant hepatitis
Cholestatic hepatitis
Relapsing hepatitis
 Chronic sequelae: None
Hepatitis A - Complications

Laboratory Diagnosis
 Acute infection is diagnosed by the
detection of HAV-IgM in serum.
 Past Infection i.e. immunity is
determined by the detection of HAV-
IgG.

Treatment and Prevention
 No antiviral therapy is available
 Vaccine containing inactivated HAV is
available.
 The vaccine is recommended for travelers to
developing countries, for children ages 2 to
18 years.
 Passive immunization with immune serum
globulin prior to infection or the disease.

Hepatitis 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
Diagrammatic
representation of
the hepatitis B
virion and the
surface antigen
components
EM of Hepatitis
B viron
• 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

Hepatitis B transmission
 Blood
 Needle stick injuries
 Blood transfusion
 Sexual intercourse
 Perinatally from mother to newborn

Figure 66-11. Clinical outcomes of acute hepatitis B infection. (Redrawn from White DO, Fenner F:
Medical virology, ed 3, New York, 1986, Academic Press
Clinical outcomes of Hepatitis B infections
From Murray et. al., Medical Microbiology 5th edition, 2005, Chapter 62, published by Mosby Philadelphia,,

 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

Hep B - Persistent Infection
 Persistence of HBsAg for greater than
6 months

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

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

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

 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.
Hepatitis B – e antigen

Diagnosis
 A battery of serological tests are used for the diagnosis of acute and
chronic hepatitis B infection.
 HBsAg - used as a general marker of infection.
 HBsAb - used to document recovery and/or immunity to HBV
infection.
 anti-HBc IgM - marker of acute infection.
 anti-HBcIgG - past or chronic infection.
 HBeAg - indicates active replication of virus and therefore
infectiveness.
 Anti-Hbe - virus no longer replicating. However, the patient can still
be positive for HBsAg which is made by integrated HBV.
 HBV-DNA - indicates active replication of virus, more accurate than
HBeAg especially in cases of escape mutants. Used mainly for
monitoring response to therapy.

Prevention
 Vaccination - highly effective recombinant vaccines are now
available. Vaccine can be given to those who are at increased
risk of HBV infection such as health care workers. It is also
given routinely to neonates as universal vaccination in many
countries.
 Hepatitis B Immunoglobulin - HBIG may be used to protect
persons who are exposed to hepatitis B. It is particular
efficacious within 48 hours of the incident. It may also be given
to neonates who are at increased risk of contracting hepatitis B
i.e. whose mothers are HBsAg and HBeAg positive.
 Other measures - screening of blood donors, blood and body
fluid precautions.

Chronic Hepatitis C Infection
 The spectrum of chronic hepatitis C infection is
essentially the same as chronic hepatitis B
infection.
 All the manifestations of chronic hepatitis B
infection may be seen, however, with a lower
frequency i.e. chronic persistent hepatitis, chronic
active hepatitis, cirrhosis, and hepatocellular
carcinoma.

Laboratory Diagnosis
 HCV antibody - generally used to diagnose hepatitis C
infection. Not useful in the acute phase as it takes at least 4
weeks after infection before antibody appears.
 HCV-RNA - various techniques are available e.g. PCR and
branched DNA. May be used to diagnose HCV infection in
the acute phase. However, its main use is in monitoring the
response to antiviral therapy.
 HCV-antigen - an EIA for HCV antigen is available. It is
used in the same capacity as HCV-RNA tests but is much
easier to carry out.

Treatment
 Interferon -The response rate is around 50% but
50% of responders will relapse upon withdrawal
of treatment.
 Ribavirin - there is less experience with ribavirin
than interferon. However, recent studies suggest
that a combination of interferon and ribavirin is
more effective than interferon alone.
 Vaccine is not available

HBsAg
RNA
 antigen
Hepatitis D (Delta) Virus

 Hepatitis D virus requires hepatitis B virus (HBV)
for its replication. HDV infection occurs only
simultaneously or as super-infection with HBV.
 Same route of transmission as Band C
 Immunoglobulin G (IgG) and Immunoglobulin M
(IgM) anti-HDV, and confirmed by detection of
HDV RNA in serum.
Hepatitis D - Clinical Features

 Most outbreaks associated with faecally contaminated drinking
water.
 Several other large epidemics have occurred since in the Indian
subcontinent and the USSR, China, Africa and Mexico.
 In the United States and other non-endemic areas, where
outbreaks of hepatitis E have not been documented to occur, a
low prevalence of anti-HEV (<2%) has been found in healthy
populations. The source of infection for these persons is
unknown.
 Minimal person-to-person transmission.
Hepatitis E -
Epidemiologic Features

 Avoid drinking water (and beverages with ice) of
unknown purity.
 Avoid uncooked shellfish, and uncooked
fruit/vegetables not peeled or prepared by traveler.
 Vaccine not available
Prevention and Control Measures for
Travelers to HEV-Endemic Regions

Window Peroid
 Hepatitis B: Both serological markers HBsAg (Hepatitis B
surface antigen) and Anti-HBs (antibody against HBsAg) are
negative.
 This is due to the fact that, although there are Anti-HBs
antibodies present, they are actively bound to the HBsAg). Other
serological markers, IgM (antibody) against HBc can be positive
at this point.

immunodiagnosis of viral hepatitis students (1).ppt

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