17 - HAV Flashcards
T or F: HAV can still happen in North America
T
_______________ are a common source of HAV
Frozen berries
T or F: It takes a long time for HAV to become symptomatic
T, symptoms appear between 15 and 50 days after infection
Symptoms of HAV include:
- yellow eyes
- yellow skin
- abdominal pain
- pale stools
HAV has effects on the human _______
liver
When symptoms occur, they typically last _______
8 weeks
T or F: acute liver failure may occur, but this is generally limited to elderly patients
T
Can HAV spread via the fecal-oral route?
YES
_____________________ seafood is a common vector of transmission
undercooked contaminated
The _____________ is effective against transmission and is indeed recommended for anyone travelling to areas with lower sanitation standards
HAV vaccine
T or F: after a single infection a person is immune for the rest of their life, and the vaccine appears to be effective for life
T
T or F: no specific treatment is available for HAV
T
________ is recommended and _________ may be used to treat the nausea and diarrhea on as-needed basis
Rest
medications
Treatment of acute liver failure, if it occurs, is with a liver _______
transplant
About _____ of children in the developing world will have a HAV infection before the age of 10, most of these infections are __________ and these children will then have immunity as adults
90%
asymptomatic
Give the characteristic of HAV:
ssRNA (+)
non-enveloped
7500 bp long just like polio
HAV has one serotype and 7 different genetic groups (____ human and __ non-human primate)
4
3
The human genotypes are numbered _____
I-III
6 subtypes have been described:
IA IB IIA IIB IIIA IIIB
The non-human primate genotypes have been numbered _______
IV-VI
The HAV encodes a single ______ in which the major capsid proteins are coded for at the ________
polyprotein
N-terminal
The remainder of the polyprotein encodes a series of _____________ required for HAV RNA replication
non-structural proteins
A small protein, also known as ______, is covalently linked to the _____ end of the genomic RNA and this probably serves as the protein primer for RNA synthesis
VPG
5’
Most of this virus appears to be produced in the _____ and reaches intestinal contents by _________ from infected hepatocytes via the ________ system
liver
secretion
biliary
HAV life cycle:
- HAV binds to cellular receptor and gets into hepatocytes
- It secretes its +sense ss RNA
- The + ssRNA can be directly translated into the polyprotein
- The polyprotein is cleaved to make subunits for the capsid and the things you need for RNA replication
- +RNA can be reverse transcribed into -RNA which can then be used to make a lot more + RNA
- +RNA can then be loaded into the assembled capsid
- The assembled virus is secreted out via the biliary canalicus back into the intestinal tract
Two types of antibodies are produced to get rid of the viral infection:
- IgM (immune response to a gastrointestinal infection - peaks around week 6 and gets rid of your infection over time)
- IgG (peaks at 14 weeks out from the initial infection, IgG remains elevated as the IgM goes down - always stays up and is responsible for lasting immunity towards HAV)
______ peaks a couple weeks after the fecal HAV peak
ALT
ALT is a biomarker of ________
liver damage
Fecal shedding of the virus reaches its maximum just before the onset of ______________ injury, at which point the individual is most infectious
hepatocellular injury
______ is short lived but its presence is used to diagnose the illness
IgM
How do you detect HAV in foods
- Food is collected and suspended in a glycine buffer and mixed for 15 minutes at room temp (the virus will become suspended in the buffer)
- The supernatant from this mixture (containing the virus) is centrifuged at 170000 x g for 1 hour, at this speed the virus collects in a pellet at the bottom of the centrifuge tube
- Supernatant is discarded
- The pellet is resuspended in buffer and added to a QIA shredder to break the viral capsid and release the RNA
- RNA is precipitated and purified and can then be used in an RT-qPCR reaction to detect its presence
