Lecture 8.1: Viral Hepatitis Flashcards
What is Hepatitis?
It is a general term referring to inflammation of the liver
Causes of Hepatitis: Infectious (4)
• Viral
• Bacterial
• Fungal
• Parasitic
Causes of Hepatitis: Non-Infectious (7)
• Alcohol
• Drugs
• Chemical
• Autoimmune
• Metabolic Diseases
• Genetic
• Radiation
Signs & Symptoms of Hepatitis (11)
• Fever
• Malaise
• Upper Abdominal Discomfort/ RUQ tenderness
• Jaundice
• Development of Ascites (very uncommon)
• Oedema (very uncommon)
• Spider Naevi
• Mild Hepatomegaly
• Splenomegaly
• Persistent Nausea & Vomiting
• Hepatic Encephalopathy (in severe cases,
suggests liver failure)
What are the most common causes of Viral Hepatitis?
5 unrelated hepatotropic viruses:
• Hep A
• Hep B
• Hep C
• Hep D
• Hep E
What are some other viruses that can cause liver inflammation? (3)
• Cytomegalovirus
• Epstein–Barr Virus
• Yellow Fever
Hepatitis A Virus: Structure
• Naked RNA virus (naked icosahedral capsid, single-stranded RNA genome)
• Only 1 stable serotype
• 4 genotypes exist, but in practice most of them are group 1
Hepatitis A Virus: Transmission Types
• Close Personal Contact
• Contaminated Food
• Contaminated Water
• Blood Exposure (rare)
How does Hepatitis A invade the human body?
• Faecal-Oral Route
• Multiplies in the Intestinal Epithelium
• Reaches the Liver by Haematogenous spread
What is the Incubation period of Hepatitis A?
2 to 6 weeks
Diagnosis of Hepatitis A (8)
• Examination of Patient
• Patient History
• Complete Blood Count
• Biochemical Blood Test
• Coagulogram
• Liver Function Test
• Viral Hep Marker Analysis
• Urine and Faeces Analysis
Hepatitis E Virus Structure
• Calicivirus-like viruses
• Unenveloped RNA virus
• 32-34nm in diameter
• Positive stranded RNA genome (7.6 kb in size)
• Very labile and sensitive
Transmission of Hepatitis E
• Eating Raw Shellfish
• Sexual Contact
• Use of Non-Sterile Syringes
• Consumption of Contaminated Food and Water
• Swimming in Dirty Water
• Contact with Sick People
Hepatitis B Virus Structure
• It is a double-stranded DNA hepadnavirus
• The whole virus is called the Dane particle
• Replication involves a reverse transcriptase
• 42nm enveloped virus
• 22nm spheres and filaments other forms- no DNA in these forms so they are
not infectious (composed of surface antigen)
• These forms outnumber the actual virions
Can you culture Hep B
Not yet
HBV Antigens
HBsAg = surface (coat) protein ( 4 phenotypes : adw, adr, ayw and ayr)
HBcAg = inner core protein (a single serotype)
HBeAG = e antigen; an indicator of transmissibility
(minor component of the core- antigenically
distinct from HBcAg) secreted protein; function
unknown
Transmission of Hepatitis B (7)
• Sexual Contact
• Blood Transfusions
• Re-use of contaminated needles and syringes
• Through wounds/insect bites/animal bites
• From mother to child (MTCT) during childbirth
• Intrauterine (through placenta)
• Breastfeeding
Hepatitis B: Mechanism of Invasion
• Virus enters hepatocytes via blood
• RNA intermediate: HBV replicates through an RNA intermediate
• This produces and release antigenic decoy particles
• Reverse transcription: mRNAs is converted into the DNA
• This DNA will eventually be the core of the progeny virion
• Integration: Some DNA integrates into host genome causing carrier state
Hep B Decoy Particles: What are they? Importance?
• HBsAg-containing particles are released into the serum of infected peopl
• These outnumber the actual virions
• Spherical or filamentous
• They are immunogenic
• Were processed into the first commercial vaccine against HBV.
Diagnosis of Hepatitis B
• Examination of Patient
• Patient History
• Complete Blood Count
• Biochemical Blood Test
• Liver Function Test
• Viral Hep Marker Analysis
• Ultrasonography of Abdomen
Importance of HBeAg in HBV
Hepatitis B e antigen (HBeAg) is an indicator of viral replication
Importance of HBsAg and HBsAb in HBV
HBsAg - used as a general marker of infection
HBsAb - used to document recovery and/or immunity to HBV infection
Importance of Serum anti HBc
It is most useful & inexpensive marker for identification of occult HBV infection in HBsAg negative individuals
What is an Occult HBV Infection?
• Presence of HBV DNA in the liver
• Detectable (< 200 IU/ml)
• Undetectable HBV DNA in serum
• HBs Ag negative
• Anti HBc antibodies
Hepatitis D (Delta) Virus Structure
• Virion: spherical, 36-38 nm,
• HBV capsid, HDV nucleoprotein
• Delta antigen
• HBsAg
• Nucleic Acid: (-) ss RNA, circular
• Satellite virus : replicates only in the presence of HBV
When can Hep D be contracted?
You can only contract this is you are also currently suffering from Hepatitis B
Consequences of Hepatitis B & Delta Virus Infection: Co-Infection
• Co-Infection
• Severe acute disease
• Low risk of chronic infection
Consequences of Hepatitis B & Delta Virus Infection: Superinfection
• Usually develop chronic HDV infection
• High risk of severe chronic liver disease
• May present as an acute hepatitis
Hepatitis C Structure
• Hepatitis C virus (HCV) is a single-stranded RNA flavivirus
• Envelope
• Envelope Proteins (E1 & E2)
• Nucleocapsid
• RNA
Transmission of Hepatitis C (7)
• Sexual Contact
• Blood Transfusions
• During Operations
• Re-use of contaminated needles and syringes
• From mother to child (MTCT) during childbirth
• Intrauterine (through placenta)
• As a consequence of Infectious/Bacterial Infection Complications
Signs & Symptoms of Hep C: Acute Infection (7)
• Decreased Appetite
• Fatigue
• Nausea
• Muscle or Joint Pains
• Weight Loss
• Acute Liver Failure (rare)
• Jaundice
Signs & Symptoms of Hep C: Chronic Infection
• Fatigue
• Mild Cognitive Problems
• Fatty Liver
• Cirrhosis
• Hepatocellular Carcinoma
• Ascites
• Easy Bruising/Bleeding
• Varices (enlarged veins)
• Hepatic Encephalopathy
What is the Incubation Period of Hep C?
1-26 weeks
Stages of Liver in Acute Hepatitis (3)
Healthy Liver
Acute Hepatitis
Recovered Liver
Stages of Liver in Chronic Hepatitis (4)
Healthy Liver
Chronic Hepatitis
Liver Cirrhosis
Liver Cancer (hepatocellular carcinoma)
How many Acute HCV turn into Chronic HCV?
C. 85%
Treatment of Hep C
• Combination of pegylated interferon alpha and the antiviral drug ribavirin for.
period of 24 or 48 weeks
• Hepatitis C is a common reason for liver transplant
• Ribavirin
What are 5- of the many- Functions of the Liver? (9)
• URH
• Bile Production
• Filtering of Toxins
• Excretion of bilirubin cholesterol, hormones, and drugs
• Breakdown of carbohydrates, fats, and proteins
• Activation of enzymes
• Storage of glycogen, minerals, and vitamins (A, D, E, and K)
• Synthesis of blood proteins
• Synthesis of clotting factors
