GI Infections 2 Flashcards
vaccines for HBV are made against _____
surface envelope glycoprotein
acute infection of HBV is characterized by the presence of which antigens?
HBsAg and HBeAg (surface and early antigen)
AND IgM against the core antigen
what would you expect to see in a chronic infection of HBV
- anti HBc (antibodies against HBc)
- HBs Ag and HBeAg detected for years
HDV Is ______ sensed ____ genome
negative sense ssRNA genome
what is the window period?
the time frame between the absence of the surface antigen and the antibody to it so during this period is measured using the IgM against the core antigen (anti-HBc)
serology results:
- HBsAg +
- anti- HBc +
- IgM anti HBc -
- anti HBs -
someone who has been chronically infected by HBV
to kill HBV infected hepatocytes, MHC Class I restricted and CD8 T cells are directed against __________
HBcAg (core) and HBsAg (envelope)
antibody against ____ is a marker for acute infection of HBV, especially during the window period
IgM against core antigen (HBcAg)
mammals ingest ______ form of fasciola
metacercariae
describe the life cycle of Fasciola
- eggs release miracidia which invade snails
- cercariae released from snails and encyst as metacercariae on aquatic vegetation
- mammals ingest the metacercariae and they excyst in the duodenum
- migrate to the intestinal wall/peritoneal cavity and liver parenchyma into the biliary ducts
___ is the form of fasciola that invades snails
miracidia
which is more infective? HBV or HIV?
HBV; HBV remains infective in blood outside the body for up to 7 days
Hepatitis B virus is a RNA/DNA virus belonging to the family ________
DNA virus from the Hepadnaviridae family
once HBV gets to the liver, it targets the _____
hepatocytes and Kupffer cells but it is NOT directly cytopathic to liver cells
if HBsAg is positive, that indicates _____
current infection: acute or chronic
metacercariae excyst in the ______ of the human
duodenum
name 3 trematodes associated with the biliary tree
- fascioliasis
- clonorchiasis
- opistorchiasis
what are the surface glycoproteins found on HBV?
surface antigens: S, M, and L (small medium and large)
you see Anti-HBc in serology. what is this indicative of?
window period (acute infection)
describe the genome of HDV
- enveloped negative sense RNA genome single stranded rod shaped
when HBV is creating the partial dsDNA using the RT, the RNA part has to be degraded by RNAase H. what protein in the HBV ORF has this activity
ORF P
DNA polymerase, RT and RNase H activity
describe the replication process of HBV:
- once in the host nucleus, HBV will fix its partial dsDNA and create a covalently closed circular DNA (CCC)
- host DNA dependent RNA polymerase generates 4 mRNA’s of which 1 is full length RNA
- HBV’s reverse transcriptase then converts the pre genomic full length RNA to partial dsDNA
if a patients serology for anti-HBs is positive, what are some possibilities for their infection status of HBV
- immune dune to natural infection
- immune due to HBV vaccination
which hepatitis is part of the hepadnaviridae family?
HBV
is HBV enveloped? describe the structure of its genetic material
enveloped but relatively resistant to freezing, detergents and moderate heat.
partial dsDNA circular genome (one strand is larger than the other)
______ codes for the HBeAg (early antigen) in HBV
ORF C; also code for the HBcAg
acute/chronic form of HBV can develop into hepatocellular carcinoma
chronic
HBV is stable/unstable at low pH
stable (unique)
replication of HBV occurs in _______
host nucleus
why does HDV require the presence of HBV to survive?
- HDV envelope contains HBsAg derived from HBV
intermediate host of the fasciola is _______
definitive host is:
intermediate host: snail
definitive host: sheep, goat, cattle and other herbivores from which shed the fasciola sp. in their feces
What is a Dane particle?
non infectious HBV viral particles that are there to produce an immune response (cytokine storm) but have no genetic material inside to replicate (act as a decoy)
infective form of fasciola is _______
metacercariae (same with C. bu the intermediate host is fish)
______ protein is responsible for the poly or monoclonal expansion of the cell in HBV infection. It is coded for by _________
HBx protein coded by ORF X
when you see positive anti-HBs what are some possibilities for the infection status of HBV in that patient
- immune dure to naturel infection or immune due to HBV vaccination
what is the form of fasciola that you can find on the aquatic vegetation
metacercariae
ORF S codes for _______ in HBV
surface proteins (S, M, or L)
