GI Viruses Flashcards
viruses that enter the GI must be ________, resistant to ______ in the GI tract, and generally transmitted via ________ and must be able to survive in environment
acid stable
enzymes
fecal-oral route
5 GI viruses?
- picornaviruses (enteroviruses)
- rotaviruses
- calciviruses
- astroviruses
- adenovirus
polio, coxsackie A and B, echoirus, enterovirus, hepA, and rhinoviruses all belong to what virus family?
picornavirus (enterovirus)
- small icosahedral viruses, family picornaviridae
- positive polarity RNA
- translated as polyprotein
- relatively stable
enteroviruses
picornaviruses replicate rapidly, in as little as _____ hours
6
_______ rather than immune pathology is responsible for causing disease pathology in enteroviruses
viral replication
_______ antibody is transitory but can prevent the initiation of infection, and _____ antibody prevents viremic spread to target tissue preventing disease
secretory
serum
- humans the only host
- tropism for central nervous system
- extensive necrosis of neurons in gray matter, affecting anterior horn of spinal cord
poliovirus
90% of polio infections are asymptomatic, where virus infection limited to?
oropharynx and gut
5% of polio infections result in _________, characterized by headache, fever, malaise, sore throat, and vomiting
abortive polio/minor illness
1-2% of polio infections results in _________, where virus progresses to CNS and meninges, get back pain and muscle aches
non-paralytic polio/asceptic meningitis
0.1 to 2% of infections lead to _______, where virus spreads to anterior horn cells of spinal cord and motor cortex
paralytic polio
enteroviruses as a group cause the most cases of what?
asceptic meningitis
- Salk vaccine
- good stability and transport, safe in immunodeficient, no risk of vaccine related disease
- lack of gut immunity, need booster, needs to be injected, higher community immunization levels needed
inactivated poliovirus vaccine
- Sabin vaccine
- effective, lifelong immunity, induction of secretory antibody response similar to natural infection, no need for boosters, her immunity attenuated virus circulating in community
- risk of vaccine associated poliomyelitis, spread of vaccine to contacts without their consent, unsafe for immunodeficient
live oral polio vaccine
common coxsackie and echovirus infections?
herpangina (painful ulcers on palate and tongue), hand foot mouth disease, pleurodynia (fever and intense pain chest area and abdomen), myocardial and pericardial infections, viral asceptic meningitis
herpangina caused by _________ virus, causing soft palate lesions, fever, sore throat, anorexia, vomiting
coxsackie A
hand foot mouth disease caused by ________ virus, patient can but mildly febrile, self limiting
coxsackie A
known as devil’s grip, associated with coxsackie B virus, unilateral low thoracic peluritic chest pain, average of 4 days, treat with analgesics
pleurodynia
myocarditis caused by coxsackie B virus –> infiltrate of ______
lymphocytes
- presenting symptom may be headache, neck stiffness and photophobia, younger children may have diarrhea, rash, and cough
- erythematous rash, maculopapular, and vesicular
- fever up to 5 days
- anorexia, nausea, vomiting
- sore throat
- caused by coxsackie A and B, must be differentiated from bacterial
asceptic meningitis
- segmented, double stranded RNA
- 11 segments are rotaviruses
reoviridae
rotavirus inner capsid antigen ______ has the group determinants, outer capsid antigens ________
VP6
VP7, VP4
rotavirus:
spread by _______ route
______ infection of intestinal epithelium causes loss of electrolytes and prevents readsorption of water
-large amounts of ______ are released during diarrheal phase
fecal oral
cytolytic
virus
incubation period of rotavirus?
about 3 days
rotavirus enterotoxin incorporated into the ER membrane, actively secreted from the apical membrane of polarized epithelial cells, attributed to anion secretion, virus release, calcium mobilization, protein kinase C activation, golgi independent vesicle trafficking for virus exit
NSP4
ingestion of rotavirus particles leads to infection of adsorptive ________ cells, stimulation of ________, and enterotoxin _____ ; leading to osmotic diarrhea
intestinal villus cells
enteric nervous sytem
NSP4
quick easy ways to detect rotavirus in stools
EIA or latex agglutination
the segmented genomes of rotavirus can undergo ______, initial infection and recovery from initial rotavirus infection rarely induces ______
genetic reassortment
sterilizing immunity
live attenuated (rotateq, rotarix) rotavirus vaccines have been developed, not meant to induce ________ but to prevent _______
sterilizing immunity
severe disease
- small non-enveloped viruses
- (+) ssRNA
- cause outbreaks of gastroenteritis, generally resolves within 48 hours
- species: norwalk virus, norovirus
calciviruses
- transmittted by fecally contaminated water or food, or aerosolization
- most common cause of gastroenteritis in the world
- generally self limting within 48 hours
- outbreaks on cruise ships, etc
norwalk virus
diagnosis of norwalk virus done by?
RT-qPCR assays
- small RNA viruses
- assoc’d with cases of endemic gastroenteritis, usually in young children and neonates
- responsible for up to 10% of cases of viral gastroenteritis
- diagnosed by electron microscopy only
astroviruses
