Lecture 5 (Hepatitis) Flashcards
Hepatits Types
A,B,C,D,E,G Virus
What part of the body does hepatitis affect?
the liver
Hep A
Typically, hepatitis A is an acute infection, meaning it is a short-term illness. Most people recover fully within a few weeks to a couple of months. Chronic hepatitis A is rare.
Hep B
Hepatitis B can be either acute or chronic. Many adults with acute HBV recover fully, but some may develop chronic hepatitis B, which can lead to long-term liver problems.
Hep C
Hepatitis C is often a chronic infection. While some people may have an acute hepatitis C infection and clear the virus on their own, many individuals develop chronic hepatitis C, which can lead to liver damage over time.
Hep D
Hepatitis D can cause both acute and chronic infections. HDV is a defective virus that requires HBV for replication, so it is typically seen in individuals already infected with HBV.
Hepatitis E virus
Hepatitis E is usually an acute infection, and most people recover without long-term complications. Chronic hepatitis E is rare.
What types of viruses cause hepatitis?
A diverse type including delia virus, picornavirus, flavivirus, etc
Tropism of Hepatitis?
The liver
Where do they replicate?
In the hepatocytes (liver cells)
Hepatitis A (HAV)
picornavirus (RNA+)
Hepatitis B (HBV)
hepadnavirus (dsDNA)
Hepatitis C (HCV)
flavivirus (RNA+)
Hepatitis D (HDV)
delta virus (RNA-)
Hepatitis E (HEV) -
calicivirus-like (RNA+)
Variation of Chronic Infection chance
Hepatitis B (HBV) and Hepatitis C (HCV) infections often become chronic, potentially leading to long-term liver problems.
Hepatitis A (HAV) and Hepatitis E (HEV) typically cause acute, short-term infections with a low risk of chronicity.
Hepatitis D (HDV) can lead to chronic infections, but it usually occurs in individuals already infected with HBV.
Hep A Properties-
Section title
srction title
Hepatitis A (HAV):
Hepatitis A is a highly contagious viral infection of the liver caused by the hepatitis A virus (HAV).
genome type? HAV
ssRNA (+) Picornavirus.
A single-stranded, positive-sense RNA virus from the Picornaviridae family,
how is Hep A spread?
contaminated food, shellfish & water
How does Hep A reach the liver?
Through the hepatic portal system
Where does Hep A replicate?
Slowly replicates in hepatocytes
But it is not cytopathic (won’t damage the cell It infects)
Where will Hep A shed?
In the bile via the bile duct &
shed in stool 10 days before symptoms
how does Hep A get cleared?
NK Cells, CD8 cells, and antibodies **
What are the symptoms of Hep A
Symptoms – fever, anorexia, nausea, jaundice
Is Hep A chronic? Oncogenic?
Not chronic, not oncogenic (cancer causing)
Transmission of Hep A
Orally transmitted, will pass through the GI tract, cross into the blood, go to the liver. Will be shed in the bile & the stool.
Capsid Hep A
icosahedral shape
Envelope? Hep A
non-enveloped
Look at slide 10 for the chart
ALT increase in HEP A
The level of alanine aminotransferase (ALT), an enzyme that is released into the blood when liver cells are damaged, begins to rise.
IgG antibodies (Hep A)
IgG antibodies are produced by the body in response to the virus. IgG antibodies are more persistent than IgM antibodies and can be detected in the blood for months or even years after the infection has resolved.
IgM Antibodies (Hep A)
IgM antibodies are produced by the body early in an infection, while IgG antibodies are produced later in the infection. IgM antibodies are not as specific to the virus as IgG antibodies, but they are produced more quickly
What is an enveloped virion of Hepatitis B?
An enveloped virion
What classification does Hepatitis B belong to?
: Hepatitis B is a Hepadnavirus, a family of DNA viruses known for causing Hepatitis B.
What is HBsAg
Hepatitis B Surface Antigen
How many forms of HBsAg are there?
three
HBeAg
HBeAg is an antigen associated with active viral replication and a marker of high infectivity.
What genome type does Hep B Have .
Hepatitis B is a partial double-stranded DNA virus, meaning it has an incomplete genome consisting of partially double-stranded DNA
What is the Dane particle, and what role do antigenic decoy particles (HBsAg) play in Hepatitis B?
The Dane particle is the complete infectious Hepatitis B virion, and antigenic decoy particles (HBsAg) can be produced to evade the immune system.
What is the structure formed by HBcAg in the Hepatitis B virus?
HBcAg forms an icosahedral capsid, which encloses the viral DNA
Reverse Transcriptase & Protein Kinase (HEP B)
The virus contains reverse transcriptase, which replicates the viral genome through an RNA intermediate, and a protein kinase.
Modes of transmission: (Hep B)
Hepatitis B is transmitted through blood, semen, saliva, breast milk, menstrual and vaginal secretions, and amniotic fluid.
What are the two possible outcomes of Hepatitis B infection, and how do they differ?
Hepatitis B can lead to either acute or chronic infections, with acute infections being self-limiting, and chronic infections persisting for a longer duration.
How can Hepatitis B infections manifest, and what’s the difference between symptomatic and asymptomatic disease?
Hepatitis B infections can be symptomatic, causing noticeable symptoms, or asymptomatic, where individuals show no obvious signs of infection
How does the Hepatitis B virus replicate in hepatocytes, and what is its impact on the liver?
The virus replicates slowly in hepatocytes with minimal cytopathic damage, but chronic infections can lead to liver damage over time.
HBV
The HBV virus that can infect the liver.
HBsAg
HBsAg is a protein that is found on the surface of the HBV virus.
HBcAg
Core antigen
Found in nucleus
HBeAg
Glycoprotein,
associated with the core-antigen
used as a marker of infectivity
only seen when HBsAg is also present
Anti-HBs
Anti-HBs is an antibody that is produced by the body in response to HBsAg.
Anti-HBc
Anti-HBc is an antibody that is produced by the body in response to HBcAg
Anti-HBe
Anti-HBe is an antibody that is produced by the body in response to HBeAg.
HBV Structure - Dane Particle
The complete virus particle of HBV is called a Dane particle. It consists of a virion with a lipid bilayer envelope containing the HBsAg, which is composed of one major and two other proteins. This structure is responsible for the infectious nature of the virus.
Structure of Hep B
Can be spherical or elongated
Life cycle of Hep B
(nothing new)
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Attachment and Entry:
- HBV attaches to hepatocytes (liver cells) and enters them.
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Replication:
- Viral DNA is transported to the cell’s nucleus, where it forms covalently closed circular DNA (cccDNA).
- Transcription and translation of viral proteins occur.
- The viral polymerase performs reverse transcription.
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Assembly and Encapsidation:
- New viral particles, including Dane particles, are assembled.
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Release:
- Viral particles are secreted into the bloodstream, spreading the infection.
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Immune Response:
- The immune system may produce antibodies to fight the virus.
Chronic infection can result from the integration of cccDNA into the host cell’s genome, potentially leading to liver damage or cancer.
HBV Acute Infection:
Anitgen response
HBsAg and HbeAg will spike around 4-12 weeks
Anti-HBc and HBeAg Detection (Weeks 4-12):
Anti-HBc (Antibodies against Hepatitis B Core Antigen) is detectable during this stage, indicating past or ongoing exposure to the virus.
HBeAg (Hepatitis Be Antigen) may be present in the blood, signifying high viral replication and infectivity.
Anti-HBs Development (Weeks 8-12 and beyond):
Over the course of several weeks, the body starts producing antibodies against HBsAg, known as Anti-HBs (Antibodies against Hepatitis B Surface Antigen).
The appearance of Anti-HBs indicates the development of immunity and a resolution of the acute infection.
Clearance or Progression (Varies):
For some individuals, the immune response is effective in clearing the virus, leading to recovery from the acute infection.
In other cases, especially when the virus persists and chronic HBV infection develops, the timeline and outcomes can vary.
Chronic Infection of Hep B
Antibodies to HBsAg and HBeAg are not detected.
Anti-HBc, antibody to hepatitis B core antigen; HBeAg - detected
This sequence reflects a lack of successful immune control over the virus, leading to continuous viral replication and a more severe form of chronic hepatitis B. The absence of detectable antibodies to HBsAg and HBeAg indicates a compromised immune response, which can contribute to ongoing liver inflammation and damage.
Disease Progression of HBV
Acute: will be resolved.
Chronic: Limited immune response, can lead into fulminant hepatis, carcinomas or cirrhosis
Spread of HBV
Viremia spreads it through the body, and can be transmitted to neonates through the blood esp. if mother is involved in IV drug abuse
What can HBV lead to?
jaundice, anorexia, RUQ pain, nausea, itching, etc.
HBV Clinical ourcomes
This Is all acute & 90% of HBV will be resolved or at least only be active fro 6 months before being resolved
4 stages of acute disease include
Incubation Period: The time between exposure to a pathogen and the appearance of symptoms.
Prodromal Stage: Early signs and symptoms that are often non-specific and can precede the full-blown disease.
Acute Stage: The phase during which the disease reaches its peak intensity, and specific symptoms become evident.
Convalescent Stage: The period of recovery when symptoms gradually subside, and the individual begins to regain health.
