Week 17 - Hepatitis C Flashcards
Outline Herpes Simplex Type 1 and 2
Herpes simplex type 1
Cutaneous exposure
Belongs to Herpesviridae family of viruses
Acute infection
Do you clear infection?
Establishment of latent infection in dorsal root ganglia innervating the mucosal areas involved in acute infection
Virus never eliminated
Why are symptoms severe in some cases? – immunodeficiency
Herpes simplex type 2 genital herpes
Diagnosis is usually based on symptoms.
Genital infection, take a swab and send for laboratory testing using PCR for DNA amplification
Outline Varicella Zoster virus
Varicella Zoster virus chickenpox Also belongs to the Herpesviridae familyDiagnosis of chickenpox is usually based on symptoms. Can take a swab of the base of the ulcer and carry out PCR.Virus Latency in dorsal root gangliaReactivations in shinglesOnce infected virus is never completely cleared
Outline Cytomegalovirs
Very common, stays in lymphocytes
Can cause hearing, visual, intellectual impairment, can be passed to foetus
Outline Epstein Barr vieus
Causes glandular fever, in herpesviridae group, latent in lymphocytes, passed through saliva, blood, semen
Can diagnose with IgM antibody test
Key structural points on viruses
Size - small You can’t see the virus under light microscope. Need electron microscope Shape – a large number are icosahedral Can be enveloped or non enveloped The nucleic acid – DNA or RNA
How do Hepatitis B viruses evade immune response?
Immune response targets surface antigen, other antigens are able to cause infection as not all viruses are complete and they are able to escape detection
What are the cancer causing mechanisms of Hepatitis B?
Hepatitis B virus no oncogenes. How does it cause cancer?
Long latency period between HBV infection and the development of hepatocellular carcinoma
Integrated viral DNA may cause the cell to produce altered proteins. These altered proteins in turn can activate oncogenes
Alternatively increased chronic inflammation may increase cell turnover and regeneration. This can lead to activation of cellular growth genes
What is the strongest risk factor for Hepatitis C?
Drug use / sharing needles
What does a patient require to be infected with Hepatitis D?
Co-exists with Hepatitis B virus
Examples of viruses your body can clear
Common cold – rhinovirus
Influenza
Diarrhoea – rotavirus norovirus
Sore throat - adenovirus
What is key in vaccine design?
Knowing which antigens are key for attachment to other cells and targeting those
List viruses that cause human disease
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Describe the structure of hepatitis B
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Describe the structure of hepatitis C
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Describe how viruses evade the immune response and cause chronic infection
Proteins can change (like flu)
Or different types of the same virus
Humoral and cell mediate immune response both take time so virus is at an advantage
Body attacks surface antigen, but may not attack the more dangerous core antigens
Compare the routes of transmission and risk factors of hepatitis A, B, D, C and E viruses
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Describe the long-term complications of chronic hepatitis B
The risk for chronic infection varies according to the age at infection and is greatest among young children. Approximately 90% of infants and 25%–50% of children aged 1–5 years will remain chronically infected with HBV. By contrast, approximately 95% of adults recover completely from HBV infection and do not become chronically infected (10).
When chronic, causes hepatocellular carcinoma
Describe the long-term complications of chronic hepatitis C
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Simply describe the role of cell mediated immune response in defence against infectious organisms
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Why do we need cell-mediated immunity?
B-cells are not enough
Need cell mediated to help fight antigens on the INSIDE of the cell (antibodies help prevent binding on OUTSIDE)
What are come intracellular microbes that cell mediated response helps to address? (3)
intracellular bacteria (following phagocytosis)
Viruses
Parasites
Types of T cells (4) and roles
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How do T cells recognise antigens?
Cannot recognise antigens in free form - they need to be taken up and presented by APC
What do T cells recognise on the pathogen?
They mostly recognise peptides
A small group recognise antigens that are not peptides
Difference in antigen presentation between CD4 and CD8 cells
CD4: MHC class II CD8: MHC class I Because of their specific structures
Describe shape of T cell receptor
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What is the Major histocompatibility complex (MHC)? Where are they found?
Molecules that display peptides from different antigens
MHC I: All nucleated cells
MHC II: APCs - dendritic cells and macrophages
Describe antigen binding process
xxx
What is an antigen presenting cells (APCs)?
xxx
What is the process for T cell activation? (steps with APCs)
Signal 1
Signal 2
Signal 3
And then what…. XXX
What are the different pathways that antigens can be processed by?
Pathogens that live outside the cell
Pathogens that live inside the cytosol
How are pathogens that live outside the cells processed? (and what type of T cell, what is the pathogen likely to be?)
CD4, Bacteria
COPY PASTE SLIDE (add the invariant chain, HLA-DM role)
How are pathogens that live inside the cells processed? (and what type of T cell, what is the pathogen likely to be?)
CD8, virus
LOOK AT SLIDE
What are CD4 cells?
H-helper 1 and 2, Th17,
Th1 - help phagocytes to kill ingested microbes
Th2:
XXX FROM SLIDE
What are CD8 cells?
xxx
Types of Regulatory T Cells?
xxx
How do we differentiate between Th cells?
They produce different cytokines
Th1 - Intreferon gamma which activate phagocytes (macrophages) and stimulate IgG antibodies (they tell B cells to switch from IgM to IgG)
What are some Th1 mediated diseases? (2)
Granulomas, autoimmunity
What is the role of Tcells in supporting phagocytosis? Why is this necessary?
xxx
Make them better, especially important if phagocytes can be evades
What is the role of interferon in the th1-mediated immune response?
xxx
Outline the Th2 mediated immune response
xxx
Why are helminths difficult for the body to eliminate
They are too large for phagocytosis
They have a thick coat that is resistant to microbicidal activities of macrophage
Outline role of CD8 CTL cells - how do they function? What are the key cytolytic proteins? (2)
xxx
What are the general stages of clinical diagnosis of acute viral hepatitis?
Stage 1 - Usually asymptommatic, virus replicating
Stage 2- Range of symptoms, many general
Stage 3 - Worsening symptoms, hepatomegaly, dark urine and light stool
Stage 4 - Symptoms and jaundice resole, liver enzymes return to normal
Factors required for clinical diagnosis of viral hepatitis
COPY AND PASTE FROM SLIDE
Laboratory tests for hepatitis
COPY AND PASTE FROM SLIDE
Outline the course, symptoms, prognosis, vaccination / treatment options for HEPATITIS A
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Outline the course, symptoms, prognosis, vaccination / treatment options for HEPATITIS B
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Spread via fluids
How does age at which HBV acquired affect likelihood of chronic infection?
At birth 90%
To 2-5% over 16yo
What is the signficance of picking up HBV surface antigen on test?
Patient as active HBV infection, but you don’t know if it is acute or chronic
What is the signficance of a ‘high infectivity’ and ‘low infectivity’ chronic HBV patient?
Much more likely to develop serious long term complications such as hepatocellular carcinoma
If someone has been vaccinated, which one test is positive?
Anti-HBs (everything else should be negative)
What are the treatment options for hepatitis B?
Treatable in some patients - only in chronic patients (after 6 months of active infection)
Pegylated interferon and/or antiviral agent
Outline the course, symptoms, prognosis, vaccination / treatment options for HEPATITIS C
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Outline the course, symptoms, prognosis, vaccination / treatment options for HEPATITIS D
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Detected by looking for HBV, and then looking for HDV RNA
Outline the course, symptoms, prognosis, vaccination / treatment options for HEPATITIS E
E stands for enteric (water bourne outbreaks, can be spread in pork)
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What are some other causes of viral hepatitis? (2)
Cytomegalovirus
Epstein Barr virus
Others??
Discuss lifestyle factors to manage viral hepatitis
Prevent further damage to liver Avoid alcohol, anything that can damage liver (inclu medications) Prevent spread Wash hands, hygiene techniques, careful food preparation No shared needles No donations, blood / organs Inform doctors / dentists / partners ETC
