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49 Cards in this Set
- Front
- Back
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The outcome of hepatitis depends on:
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the virus and the patient’s immune response
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Describe the HAV genome
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Single stranded, non-segmented, positive-sense genomic RNA
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How is HAV acquired
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Fecal-oral
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How is HAV immunity determined?
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HAV immunity is determined by the detection of HAV-IgG by EIA
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Is HBV cytolytic
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HBV is non-cytolytic.
Cell death and disease are immune-mediated. |
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What is the main means of transmission of HBV in high prevalence populations?
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Perinatal transmission
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What are the serological and clinical patterns observed during an acute HBV infection?
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HBsAg and HBcAg detected in serum early in infection. Later detect anti-HBe. Development of anti-HBe is a good prognostic sign associated with clearance of virus-infected hepatocytes and cessation of viral replication
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What is HBsAg used for
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It is used as a general marker of infection
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What viruses cause chronic infection
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Hepatitis types B,C, and D
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What is HBeAg used for
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It indicates active replication of virus and therefore infectiveness
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What is HBV-DNA used for
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It indicates active replication of virus, used for monitoring response to therapy
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Why is the development of anti-HBe a good prognostic sign?
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Anti-HBe is associated with clearance of virus-infected hepatocytes and cessation of viral replication
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How is the HDV genome similar to plant viroids?
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HDV contains a great deal of self-complementary sequences that give the RNA a rigid, rod shape similar to plant viroids
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HDV replication involves a ribozyme-like activity in which...
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The RNA cleaves itself at one site on the genomic RNA and one on the anti-genomic RNA strand
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Virions containing the HDV genome can be precipitated or neutralized with:
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Anti-HBsAg
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HCV accounts for 80-90% of which hepatitis?
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Post-transfusion hepatitis
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How is HCV disease different that HBV disease?
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In contrast to HBV, the majority of HCV infections (80% or more) become chronic
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What family is HCV from
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HCV belongs to the pestiviridae family and is flavivirus-like
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Why is HCV antibody detection not useful in the acute phase?
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It takes at least 7-8 weeks after infection before HCV antibody appears
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What are three treatments for HCV
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Interferon alpha - may be considered for patients with chronic active hepatitis. The response rate is around 50% but a significant number of responders will relapse upon withdrawal of treatment.
Pegylated interferon alpha (Peginterferon)– greater serum stability, longer half-life Ribavirin – not effective if used alone. A combination of interferon and ribavirin is more effective than interferon alone. Treatment regimens can be 24-48 weeks. |
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In whom do some HEV epidemics have high (20%) fatality?
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pregnant women
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What are some characteristics of Hepatitis A virus
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Picornavirus
Small, icosahedral, non-enveloped Single (+)-stranded RNA genome One serotype worldwide Strong tropism for liver Fecal-oral transmission Contaminated food and water Incubation period—10-50 days Transient viremia, virus shed in feces |
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How is immunity determined for HAV
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Detection of HAV-IgG by EIA. Prior exposure confers protection
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How is acute HAV infection diagnosed
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The detection of HAV-IgM in serum by EIA.
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What does HEV (a calicivirus) cause
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Causes an epidemic form of NANB hepatitis which is spread by water contaminated with fecal materials.
does not cause a chronic infection |
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What are the characteristics of HBV
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Virion: 42 nm Dane particle, infectious
22 nm spheres or filaments do not contain viral DNA, non-infectious Enveloped with circular, partially double-stranded DNA genome, 3.2 kB Subtypes: a, d/y, w/r Viral core contains HBcAg, DNA polymerase, and viral DNA |
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How is HBV transmitted
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Sexual - sex workers and homosexuals are particularly at risk
Parenteral - IVDA, Health Workers are at increased risk Perinatal - Mothers who are HBeAg positive are much more likely to transmit to their offspring than those who are not. Perinatal transmission is the main means of transmission in high prevalence populations |
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What is the spectrum of Chronic Hepatitis B Diseases
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1. Chronic Persistent Hepatitis - asymptomatic
2. Chronic Active Hepatitis - symptomatic exacerbations of hepatitis 3. Cirrhosis of Liver 4. Hepatocellular Carcinoma (HBV is the primary cause of this disease) |
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What is HBsAb used for
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Document recovery and/or immunity to HBV infection.
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What is anti-HBc IgM used for
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It is a marker of acute infection
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What is anti-HBcIgG used for
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To detect past or chronic infection
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What does presence of anti-HBe indicate
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Virus is no longer replicating. However, the patient can still be positive for HBsAG, which is made by integrated HBV
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What is the treatment for HBV
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Interferon - for HBeAg positive carriers with chronic active hepatitis. Response rate is 30 to 40%.
Lamivudine - a nucleoside analogue reverse transcriptase inhibitor. Well tolerated, most patients will respond favorably. However, tendency to relapse on cessation of treatment. Another problem is the rapid emergence of drug resistance. Successful response to treatment will result in the disappearance of HBsAg, HBV-DNA, and seroconversion to HBeAg. |
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What two vaccines are available for HBV
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Subunit vaccine of HBsAg prepared from patients blood.
Cloned subunit vaccine (HBsAg expressed in yeast) is used in the US and may be safer. |
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Who should receive HBV vaccination
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People at high risk of HBV infection, e.g. health care workers.
Neonates, as universal vaccination in many countries. |
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When is passive immunization with HBV Ig given
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To prevent infection after exposure.
To neonates who are at increased risk of contracting hepatitis B, i.e. whose mothers are HBsAg and HBeAg positive |
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What are the clinical features of HDV
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Coinfection
-severe acute disease -low risk of chronic infection Superinfection -usually develop chronic HDV infection -high risk of severe chronic liver disease -may present as an acute hepatitis |
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How is HDV transmitted
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Percutanous exposures
-injecting drug use Permucosal exposures -sex contact |
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What are preventative steps for HDV
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HBV-HDV Coinfection: Pre or postexposure prophylaxis to prevent HBV infection
HBV-HDV Superinfection: Education to reduce risk behaviors among persons with chronic HBV infection |
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What are some clinical features of HCV
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Incubation period: Average 6-7 wks, Range 2-26 wks
Clinical illness (jaundice): 30-40% (20-30%) Chronic hepatitis: 70% Persistent infection: 85-100% Immunity:No protective antibody |
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What are the characteristics of chronic Hepatitis C infection
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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, albeit with a lower frequency i.e. chronic persistent hepatitis, chronic active hepatitis, cirrhosis, and hepatocellular carcinoma |
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What are the risk factors associated with
transmission of HCV |
Transfusion or transplant from infected donor
Injecting drug use Hemodialysis (yrs on treatment) Accidental injuries with needles/sharps Sexual/household exposure to anti-HCV-positive contact Multiple sex partners Birth to HCV-infected mother |
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How is HCV diagnosed in the laboratory
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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. |
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How is HCV treated
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Interferon - may be considered for patients with chronic active hepatitis. 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. |
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Why is is difficult to develop vaccines against HCV
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High mutation rates, many genotypes
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Vaccines against which Hepatitis viruses can provide life-long protection
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HAV and HBV. Vaccine against HBV can protect against hepatitis and hepatocellular carcinoma caused by both HBV and HDV
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What does CCC DNA in HBV do
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Directs the transcription of larger than genome size RNA copies using host cell RNA polymerase II
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The replicative strategy of which Hepatitis virus is similar to those of retroviruses such as HIV and HTLV
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HBV. Viral polymerase carries out RNA dependent DNA synthesis (reverse transcription) in the cytoplasm using both a protein (the polymerase itself) and an RNA as primers for minus strand and plus strand DNA synthesis respectively
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What is principally responsible for the development of hepatocellular carcinoma in HBV infection
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The chronic liver damage and liver regeneration. Frequent chromosomal integration of viral DNA may also play a role
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