Flashcards in Microbiology - Hepatitis viruses - Rebecca Greenblatt Deck (35):
Phylogeny: Hepatitis A
How is Hep A diagnosed?
Enzyme Immunoassay (EIA) for Anti-HepA IgM --> acute infection
EIA for Anti-Hep A IgG --> past infection, vaccination
Alanine aminotransferase (ALT) level: high --> ongoing liver damage
Mode of transmission: Hepatitis A
Human to human
Phylogeny of Hep E
Where is Hep E endemic?
Mortality in pregnant patients is higher in Hep A or E?
Mode of transmission: Hep E
Hep A and E are DNA or RNA viruses?
Phylogeny: Hepatitis B
Small, enveloped, partially double-stranded
How many serotypes exist for Hep B?
Only one serotype, HBsAb protective against reinfection;
Effective vaccine available.
Where in the body does Hep B replicate?
Liver hepatocytes, leaves behind integrated copies of viral DNA
What is Heb B Surface antigen?
Surface Antigen appears early, ceases being detectable as surface antibody is produced, resumes being detectable in chronic
What is Heb B Surface antibody?
Surface Antibody becomes detectable as surface antigen levels fall, raised by both vaccine and infection
What is Hep B Core Antibody?
Core Antibody arises a little later, stays: IgM for acute, IgG for resolved or chronic infection – not raised by vaccine
When is E antigen of Hep B detectable?
E Antigen detectable when virus most transmissible
What causes the cirrhosis in Hep B?
Ongoing cytotoxic T-cell response against infected hepatocytes causes permanent cirrhosis – virus itself is not hepatotoxic
Accumulation of Hep antigen-antibody complexes leads to kidney damage & arthritis (membranous glomerulonephritis, mostly peds)
What is the pathogenesis of Hep B cancer?
Virus genome integration, expression of viral transcriptional transactivators, and chronic inflammation can lead to cancer (primary hepatocellular carcinoma)
How does Hep B look under the microscope?
What is the treatment for Hep B?
1 year of polymerase inhibitors (lamivudine, adefovir entecavir, telbivudine)
4 months of pegylated alpha-interferon (PEG-Intron, Pegasys) Significantly toxic, will cause heavy side effects (neutropenia, thrombocytopenia, disturbances of memory, concentration, vision, headaches, depression, irritability, hypo- or hyperthyroidism, nausea, vomiting, weight loss, alopecia, interstitial fibrosis)
Same drugs may be used to treat HepB-induced glomerulonephritis.
What is Hep D?
NOT A COMPLETE VIRUS: a “defective” virus or “viriod”
Cannot replicate by itself, only in cells co-infected with HepB
1700 nucleotide circular -RNA “genome” encodes one protein: delta antigen
Mode of transmission: Hep D
Blood and sex
How does Hep D exacerbate Hep B?
Delta antigen IS cytotoxic
Dramatically increases the incidence of fulminant hepatitis
Affects ~5% of HepB carriers
How is Hep D diagnosed?
Primary screening with EIA for anti-delta antibodies
Phylogeny: Hep C
Coinfection with Hep C is common with:
Which virus, Hep B or C, has a higher potential for causing cancer?
Much higher potential for chronic infection than HepB, thus a stronger association with primary hepatocellular carcinoma (11-19%)
Which hepatitis virus presents with the mildest initial infection?
Hep C - trying to stay under the immune radar
What Hep C genotype is the most common in the U.S.?
How is Hep C diagnosed?
Serology: Liver function tests including ALT levels, albumin, bilirubin
EIA followed by RIBA
If positive, HCV genotyping
RT-PCR for viral RNA levels to assess success of therapy
What are the goals of Hep C treatment?
Goal of treatment is sustained viral response (SVR) – like remission. “Failed” treatment may still reduce risk of hepatocellular carcinoma.
What is the current Hep C treatment?
Simeprevir (inhibits protease) manufacturer claims can cure (not just SVR) serotype 1 by combined therapy with IFN and ribavirin
Sofosbuvir (inhibits polymerase) manufacturer claims can induce SVR in combined therapy with Ledipasvir (inhibits NS5A) without IFN or ribavirin
Sofosbuvir in combination with ribavirin is active against Genotypes 2&3
Where is Hep A endemic?
A is endemic in Mexico and South America
Where is Hep E endemic?
Asia and Mexico
What is the second generation treatment for Hep C?
Second-generation protease inhibitors combined with IFN improve SVR rates for HepC serotype 1