Hepatitis A and B Hepatitis A and B

Dr. Amanj Saeed MBCHB, MSc, PhDamanj.saeed@krg.org

Clinical Features of Clinical Features of Viral HepatitisViral Hepatitis

Preicteric Malaise

Anorexia

Nausea

Abdominal discomfort

Pyrexia (fever)

Icteric Pale stool/dark urine

Jaundice

Hepatitis A VirusHepatitis A VirusRNA genome, +ve single stranded RNARNA genome, +ve single stranded RNA

7.5 kb in length encodes for polypeptides 7.5 kb in length encodes for polypeptides VP1, VP2, VP3, and VP4. VP1, VP2, VP3, and VP4.

Little is known about mechanism of entery Little is known about mechanism of entery

Genome multiplication occurs in cytoplasm.Genome multiplication occurs in cytoplasm.

The genome can act as messenger RNA The genome can act as messenger RNA directlydirectly

The incoming viral RNA strand directs the The incoming viral RNA strand directs the synthesis of a large viral polyprotein, which synthesis of a large viral polyprotein, which is then cleaved in to segments. is then cleaved in to segments.

Hepatitis A VirusHepatitis A VirusTranslation of RNA dependent RNA Translation of RNA dependent RNA polymerase is crucial stem of viral life cycle. polymerase is crucial stem of viral life cycle.

Initial step is viral RNA replication is to copy Initial step is viral RNA replication is to copy the incoming genome to form the incoming genome to form complementary negative strand. , which complementary negative strand. , which serves as a template for synthesis of serves as a template for synthesis of positive genome RNA. positive genome RNA.

The assembly is complex and require The assembly is complex and require maturation cleavage of the structural maturation cleavage of the structural proteins. proteins.

Transmission and Transmission and clinical clinical

manefestation manefestation Faeco-oral route of transmissionFaeco-oral route of transmission Entry via contaminated food or waterEntry via contaminated food or water Excreted in faeces Excreted in faeces Blood and blood products, needle, and sexual contact. Blood and blood products, needle, and sexual contact.

The incubation period is 2-6 weeks.The incubation period is 2-6 weeks.

Many infections are silent Many infections are silent

Clinical features:Clinical features: Malase Malase Loss of appetite Loss of appetite Vague abdominal discomfort Vague abdominal discomfort Fever Fever Dark urine and pale faeces Dark urine and pale faeces Jaundice (first in sclera and then skin)Jaundice (first in sclera and then skin) Itching in severe cases Itching in severe cases

Transmission and Transmission and clinical clinical

manefestation manefestation Hepatitis A is self limiting Hepatitis A is self limiting

Recurrence is reported Recurrence is reported

Less severe in children Less severe in children

1/1000 fulminant hepatitis (rare)1/1000 fulminant hepatitis (rare)

Pathology Pathology HAV replicate in hepatocyte .HAV replicate in hepatocyte .

Shed in large quantities in the faeces Shed in large quantities in the faeces

Hepatitis A Virus – Hepatitis A Virus – Consequences of Consequences of

InfectionInfectionAsymptomatic infectionAsymptomatic infection

Acute icteric hepatitisAcute icteric hepatitis

Fulminant hepatitis (rare)Fulminant hepatitis (rare)

Necrosis of hepatocyte Necrosis of hepatocyte

Proliferation of kupffer and other Proliferation of kupffer and other endothelial cellsendothelial cells

Elevated liver enzyme Elevated liver enzyme

No chonicity, cirrhosis or malignant change No chonicity, cirrhosis or malignant change

Immunity to HAV Immunity to HAV Specific IgM in prodromal phase Specific IgM in prodromal phase

IgG neutralizing antibody is detectable IgG neutralizing antibody is detectable for many years.for many years.

Diagnosis Diagnosis Liver function test (raised serum Liver function test (raised serum Bilirubin and transaminases) Bilirubin and transaminases)

Depressed prothrombin level Depressed prothrombin level

Elisa for specific IgMElisa for specific IgM

Immunisation Immunisation Human normal immunoglobulin Human normal immunoglobulin

Formalin inactivated vaccine. Formalin inactivated vaccine.

HBV HBV 350-360 million people chronically 350-360 million people chronically Infected worldwide.Infected worldwide.

Dandri and Stephen LocarniniDandri and Stephen Locarnini, , New insight in the pathobiology New insight in the pathobiology of hepatitis B virus infection, Gut, April 2012. of hepatitis B virus infection, Gut, April 2012.

In europe 950 000 cases every year, 90 In europe 950 000 cases every year, 90 000 become carriers, 19 000 die of liver 000 become carriers, 19 000 die of liver cirrhosis and 5000 die of liver cancer.cirrhosis and 5000 die of liver cancer.

In US 200 000 new cases per year In US 200 000 new cases per year

Hepatitis B Virus (HBV)

• Discovered in 1965 (Blumberg et al)

• Hepadnavirus (DNA)

Source: Center for Disease Control and Prevention

DNA

Core Ag

Also eAg

Surface Ag

• Circular, partly double-stranded DNA

The HBV genome

• Very compact and contains 4 overlapping open reading frames (ORFs)

• Minus strand of viral DNA is 3.2kb

• Plus strand is shorter and variable in size (1.8 to 2.7kb)

• Upon entry into a liver cell, the viral core particle is translocated into the nucleus of the cell, the viral DNA is then repaired and matured by a virion DNA polymerase, giving rise to Covalently Closed Circular DNA (cccDNA)

Morphology Morphology Different shape Different shape

Some are 42 nm in diameter and double shelled Some are 42 nm in diameter and double shelled

others are 20-22 nm in diameter.others are 20-22 nm in diameter.

Complete virion some times called Dane particleComplete virion some times called Dane particle

The nucleocapsid contain:The nucleocapsid contain:

The DNA genomeThe DNA genome

DNA dependent DNA polymerase DNA dependent DNA polymerase

HB core antigen (HBcAg)HB core antigen (HBcAg)

HB e antigen (HBeAg)HB e antigen (HBeAg)

Genome Genome Compact genome Compact genome

Circular ds DNA Circular ds DNA

32 kbp in size 32 kbp in size

4 overlapping open reading frame ORF.4 overlapping open reading frame ORF.

The virus encode 50% more protein The virus encode 50% more protein than expected.than expected.

Replication Replication The virus attaches to hepatocyte using the The virus attaches to hepatocyte using the virion S protein ( candidate receptors include virion S protein ( candidate receptors include transferrin receptor, the asialoglycoprotien transferrin receptor, the asialoglycoprotien receptor molecule, and human liver endonexin) receptor molecule, and human liver endonexin)

The virus enters by endocytosis The virus enters by endocytosis

Virus nucleocapsid moves to the nucleus Virus nucleocapsid moves to the nucleus

Enters cell as partially ds DNAEnters cell as partially ds DNA

22ndnd strand is completed strand is completed covalently closed covalently closed circular DNA (cccDNA) (mini chromosome)circular DNA (cccDNA) (mini chromosome)

The minus strand is transcribed to give mRNA The minus strand is transcribed to give mRNA with a 3.4 kb RNA transcript called with a 3.4 kb RNA transcript called (pregenome)(pregenome)

Replication Replication Mode of genome replication is unusual Mode of genome replication is unusual include reverse transcription of DNA from include reverse transcription of DNA from RNA intermediateRNA intermediate

RT is lack of proofreading leading to high RT is lack of proofreading leading to high mutation rate.mutation rate.

Mutation occur is pre S region which is Mutation occur is pre S region which is important for viral attachment and entry.important for viral attachment and entry.

The new enveloped viruses emerge The new enveloped viruses emerge without cell lysis.without cell lysis.

Use of Reverse Use of Reverse TranscriptaseTranscriptase

HBV DNA

mRNA

Translation

Viral proteins: HBsAgHBcAgHBeAgReverse Transcriptase

The main The main antigens antigens

HBsAgHBcAgHBeAgEach HBV Ag stimulate corresponding

antibodies All HBV Ag and Ab (except HBcAg) together

with the viral DNA polymerase can be detect in the blood at various times after infection.

HBc Ag can only be detected in the hepatocyte nuclei.

Subtypes and Subtypes and genotypesgenotypes

Surface antigen determine serological specificities to determine subtype of HBV.

DNA sequencing Genetic analysis revealed 7 genotype of the

virus with %8 nucleotyde sequence difference differences

Useful for epidemiological studies

Clinical Clinical presentation presentation

Clinical features are variable and related to:

Age Sex State of immune system.Genotype of the virus

subclinical hepatitis icteric hepatitis (jaundice) Acute infection fulminant hepatitis chronic infection (5-10%) healthy carrier chronic cirrhosis hepatitis Ca liver

Natural History of HBV Infection - Adults

subclinical hepatitis icteric hepatitis (jaundice) Acute infection fulminant hepatitis chronic infection (90%) healthy carrier chronic cirrhosis hepatitis Ca liver

Natural History of HBV Infection - Neonates

Clinical features Clinical features Prodromal phase similar to that of HAVProdromal phase similar to that of HAV

Rash and arthropathyRash and arthropathy

Jaundice Jaundice

Chronic infection (5-10% in adults)Chronic infection (5-10% in adults)

HBV antigen and HBV antigen and antibody antibody

appearance appearance Increased serum amylase Increased serum amylase

Detectible HBsAgDetectible HBsAg

Followed by appearance of HBeAg and DNA Followed by appearance of HBeAg and DNA polymerase polymerase

The first antibody to appear is anti- HBcThe first antibody to appear is anti- HBc

Followed by appearance of anti-HBe (good Followed by appearance of anti-HBe (good prognostic sign) prognostic sign)

Anti HBs is the last antibody to appear and Anti HBs is the last antibody to appear and indicate full recovery and immunity to the indicate full recovery and immunity to the virus.virus.

Clinical outcome Clinical outcome

• Perinatal (mother to baby at the birth)

• Sexual

• Parenteral (unsafe injections and

transfusion)

•Other body fuids??

Hepatitis B Virus

Modes of TransmissionHepatitis B Virus

Modes of Transmission

Acute hepatitis BAcute hepatitis B

HBsAg positive

anti-HBc positive

Acute infection will either resolve or become chronic

Resolved acute HBV Resolved acute HBV infection infection

HBsAg disappears (may take up to 6 months

Serum becomes positive for

anti-HBc (IgG) - is therefore a marker of past infection

anti-HBs - may also arise as a result of vaccination

Chronic HBV Chronic HBV infectioninfection

Defined as persistence of HBsAg for > 6 months

(i) HBeAg positive

- high infectivity eg needlestick

- increased risk of inflammatory liver disease

(ii) Anti-HBe positive

- low infectivity (but …..)

- low risk of CLD (but ….)

Diagnosis Diagnosis

ELISA Reverse passive haemagglutination Latex slide testDetection of viral DNA and DNA polymerase EM

Treatment Treatment

Acute infection does not normally require treatment

HBeAg positive carrier demand treatment

INF-α (6-10 MU three times weekly reduce viral load, HBsAg and HBeAg.

Lamivudine and Famciclovir adefovir

Prevention of HBV Prevention of HBV infectioninfection

Simple precautionsSimple precautions

Hepatitis B immunoglobulin (passive Hepatitis B immunoglobulin (passive immunisation)immunisation)

Hepatitis B vaccine (active Hepatitis B vaccine (active immunisation)immunisation)

Immunisation Immunisation Vaccine (20 ug of HBsAg given IM at 0, Vaccine (20 ug of HBsAg given IM at 0, 1, and 6 months. With booster dose at 5 1, and 6 months. With booster dose at 5 year intervals for those at special riskyear intervals for those at special risk

Immunoglobulin Immunoglobulin

Who should be Who should be vaccinated?vaccinated?

Universal vaccination?Universal vaccination?

Selective vaccination?Selective vaccination?