Microbiology GI Viruses Flashcards
what are the two enteric viruses
rotavirus and norovirus
which of the enteric viruses mainly infects children
rotavirus
which of the enteric viruses mainly infects adult causing epidemic and endemic infections
norwalk (noro) virus
which virus is known to cause ulcers leading to inflammatory polyps and possibly obstruction of the colon
CMV
what three viruses are associated with immunocompromised pts resulting in acute inflammatory diarrhea
EBV, CMV, and HIV
wheel appearance
rota virus
what is the morphology of rota virus
icosahedral
what type is rota virus
double stranded segmented RNA
mild to severe diarrhea in INFANTS
rotavirus
VP1 of rotavirus
transcriptase
VP3 of rotavirus
mRNA capping
VP4 of rotavirus
hemagglutinin; surface protein involved in attachment
VP7 of rotavirus
induces the formation of neutralizing antibodies
what type of rotavirus is MOST COMMON in the united states ?
group A
pathogenesis of rotavirus
capsid of the virus protects it from stomach acid but the stomach acid partially digests and claves VP4 producing ISVP which can penetrate the cell and the ds-RNA is replicated and the VP’s are made and subsequently lyse the cell
function of NSP4 protein
part of rotavirus and promotes calcium influx into enterocytes resulting in secretion of water and loss of ions leading to watery diarrhea
immunity to rotavirus requires
IgA in the gut lumen
how is rotavirus transmittted
fecal oral transmission (it survives well on fomites and hands and there are frequent outbreaks in preschools, and daycare centers)
the Unitedstates has rotavirus outbreaks that commonly occur at what time of the year ?
WINTER
what is the method of choice for diagnosing rotavirus
direct detection of the viral antigen (EIA and latex agglutination)
what is the treatment for rotavirus
fluid and electrolyte replacement
how do you prevent rotavirus
2 live attenuated oral vaccines available which have a low risk of intussception
what type of virus is norovirus
positive sense, naked RNA virus
how are the noroviruses transmitted
fecal oral transmission
diagnosis of norovirus
RT-PCR in stool or emesis sample during outbreaks
treatment of norovirus
rehydration therapy, bismuth subslaicylate may reduce severity (peptobismol)
what type of virus is yellow fever virus
positive sense, single stranded, RNA enveloped virus
pathogenesis of yellow fever
kupffer cells are infected in 24 hours and can disseminate to the kidneys, lymph nodes, spleen, and bone marrow and can result in CONJUNCTIVAL INJECTION AND FACIAL FLUSHING during the viremic stage
symptoms of the toxic phase of yellow fever
jaundice, bleeding from the gums and venipuncture sites, black vomit (terminal phase is marked by delirium, stupor, and coma)
how do you prevent yellow fever virus
live attenuated vaccine, protective antibodies form in 7-10 day (protection last for at least 10 years)
yellow fever virus vaccine is effective in what patient population
HIV but must be greater than 200 ml
what type of virus is hepatitis A virus
picronavirus, negative RnA, naked, icosahedral, Vpg
what type of virus is hepatitis B
DNA, enveloped
what type of virus is hepatitis C
flavivirus, RNA enveloped
what type of virus is hepatitis D
delta virus, circular RNA enveloped
what type of virus is hepatits E
RNA, naked
which hepatitis viruses are fecal oral transission
A and E
which hepatitis viruses are transmitted via blood and body fluids
B through D
what are important sources of Hepatitis A virus
clams, oysters, mussels
what is the pathogenesis of HAV
the virus is ingested and then enters the blood stream via the GI tract, replicates in the hepatocytes and kupffer cells, released into bile, then stool
what is the significance of IFN in HAV
it limits viral replication
can HAV become a chronic infection
NO
icteric phase of HAV
dark urine, pale stool
yellow eyes, abdominal pain
pruritus, arthralgia,s skin rash less frequent
how do you diagnose HAV
ELISA for anti-HAV IgM
vaccine for HAV
killed AV vaccine given at 2years of age and with HBV vaccine to adults
HBV is member of
hepadnaviruses
how does HBV replicate
via reverse transcriptase and replicates via an RNA intermediate
stable vironions of HBV are called
Dane particles
virions of HBV contain
DNA
DNA poly (RT and ribonuclease activity)
protein kinase
most common cause of pediatric gastroenteritis
rotavirus
double stranded segmented RNA genome that is naked
rotavirus
cruise ships
noro virus
what is the mosquito responsible for yellow fever
aedes aegypto
what causes the symptoms of Hepatitis viruses
immune response against the virus
RNA intermediate
HBV
enzyme associated HBV
RNA dependent DNA polymerase
core antigen
we make antibodies to this in HBV
E antigen
important to tell us if the pt is actively makingthe virus
S antigen
binds hepatocytes, decoy viruses, marker for chronic disease and leads to immune complex diseases
replicates through an RNA intermediate
hepatitis B virus
only hepatitis virus that has DNA
hepatitis B
attachment to hepatocytes is mediated by _____in the hepatitis B Virus
HbSAg
what causes fulminant hepatitis
HDV (delta agent)
what is the signifiance for neutralizing Ab (nAb)
nAb made against HbsAg and later in infection, large amount of HbsAg in the serum can block nAb which limits the capacity to resolve the infection. immune complexes can form btween HbsAg and nAb (type III hypersensitivity reaction causing vasculitis, arthralgia, rash, and renal damage)
who is at risk for HBV
medical personnel
sexual promiscuity, IV drug abuse
babies born to chronic HBV positive mothers
after 6 months it is concere
chronic or resolved
Positive HbsAg
early disease
positive HbcAb, HbsAg, and HbeAg
acute disease
positive HbcAb, HbsAg and HbeAb
chronic passive (must be more thatn 6 months)
positive HbvAb, HbsAg, HbeAg
chronic active
positive HbcAb, HbsAg
resolved
positive HbsAb
vaccinated
HbsAg
indicates infection and if present it means you have the actively replicating virus, if present for greater than 6 months then you have chronic infection
AbsAb indicates
resolution or immunity
Hbs window is time between
HbsAg not detected
HbsAb cannot be detected yet so you must measure HBcAb
HbeAg
correlates with active viral replication and is present during acute disease and active chronic disease
HBeAb
usually ordered in chronic infections
HBcAb
first antibody to appear, presence indicates recent infection used during window period, both IgM and IgG Ab present
if E antigen is present
active chronic infection
what do you give for hepatitis B post exposure prophylaxid
immune globulin
chronic HBV is treated with drugs targeting what
the polymerize
what are the two drugs used to treat chronic HBV
HIV RT inhibitors and IFN-alpha for at least four months
what does IFN-alpha do
activate protein kinase that inactivates EF2
what can you get if you give immune globulin
serum sickness (type three hypersensitivity)
what does the subunit vaccine contain for HBV
HBsAg
type of virus is hepatitic C
positive sense RNA genome that is enveloped
type of hepatitis for hepatitic C
chronic
HCV replication
coats itself with LDL and VLDL an uses these receptors for uptake into hepatocytes, it also binds CD81 (tetraspanin)
treatment for HCV
recombinant INF-alpha, ribavarin, “ivir”
responsible for 40% of fulminant hepatitis infections
hepatitis D
a viral parasite
hepatitis D
what is essential for the packaging of HDV
HBsAg
genome of HDV
small, single stranded RNA genome, cicular
responsibility of ribozyme in HDV replication
cleaves delta Ag to promote association of genome with HbsAg to form the virion
when you get infected with both viruses (HBV and HDV at the same time) this is called
coinfection (less severe than superinfection)
superinfection
infected with HDV AFTER HBV infection and is a more rapid and severe progression
HEV is a
norovirus
how is HEV transmitted
fecal oral usually contaminated water
Hepatitis E is important in one patient population
pregnant patient
