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Flashcards in Micro 2 Deck (209)
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What is orthoreovirus?

A member of reoviridae
Infects mammals, but not associated with serious disease in humans.

1

What kind of virus is rotavirus?

Reoviridae
-dsRNA genome - 11 segments
-most important cause of gastroenteritis in young children
-group A assoc. w/ human disease

2

What cells do Rotavirus infect?
How long is incubation?

Tip of villi in sm. intestine
- as few as 10 particles can cause infection
-1-4 days incubation period

3

Describe rotavirus pathogenesis

virus capsid proteins attach to glycolipid receptor on the apical enterocytes of sm. intestine villi.
-Damage to sodium and glucose absorptive mechanisms -> increased luminal H2O volume. Viral replication -> acute onset of vomiting and diarrhea
-Activation of intestinal nerves -> secretion of H2O
-Fluid accumulation in lumen of sm. intestine, 10-20 diarrheal episodes / day and severe dehydration

4

Describe rotavirus structure

Unenveloped, icosahedral, 3 layer protein capsid
Segmented dsRNA genome
capsid contains all enzymes needed for replication
VP4 receptor protein - binds glycolipid of host cell

5

What are the major coat proteins of rotavirus?

VP4 - outer coat - binds receptor (sialic acid / integrins)
VP7 - outer coat - stripped during endocytosis
VP6 - middle coat - major protein that is tested for in antibody titer
VP2 - inner coat

6

How is rotavirus infection diagnosed in a lab setting?

Presence of virus particles in feces early in illness
- immune electron micoscopy, ELISA, immunoassay

Rise in titer of Ab to VP6

7

What are the two most important viruses contributing to diarrheal illness in children?

Rotovirus (reoviridae)
Adenovirus

8

What type of genetic material is carried by Adenovirus?

dsDNA

9

What is the most common cause of viral gastroenteritis in older children and adults?

Norovirus

10

How is norovirus transmitted?

fecal-oral
also contaminated food: shellfish and contaminated water

11

How long is the Norovirus incubation period and how long does it remain contagious?

incubation: 12-48 hours
From onset of symptoms: highly contagious until at least 3 days after symptoms recede - infectious viral particles may be shed as long as 2 weeks after illness

12

Norovirus symptoms

Acute onset of vomiting, diarrhea, stomach cramps, headache, fever, chills, myalgia

symptoms resolve 24-48 hours after onset.

13

How is norovirus spread prevented?

Handwashing - soap and water (alcohol hand-gel is inadequate)
10% bleach to clean surfaces.

14

What family of viruses is norovirus from?

Calicivirus

15

What is norovirus genome?

ss+RNA

16

What virus families do Hepatitis viruses A-E belong to?

Hep A: Picornavirus
Hep B: Hepadnavirus
Hep C: Flavivirus
Hep D: satellite virus - undefined classification
Hep E: Hepevirus (Hep - E - virus)

17

Genomes of Hepatitis A-E

A: ssRNA
B: dsDNA
C: ssRNA
D: ssRNA (-)
E: ssRNA

18

Which Hepatitis viruses produce chronic illness?

B and C
D in the context of association with B (is not infective on its own)

19

What causes hepatic cellular carcinoma

Chronic viral infection is leading cause (HBV, HCV)
course of chronic illness is 25-50 years
Ultimate cause: constant inflammation and constant stimulation of cellular replacement -> mutation and tumor formation

20

What was the first successful recombinant vaccine for a human disease?

Hep B vaccine

21

How is HBV spread?

sexual contact and parenteral exposure

most adults clear infection - 5% do not -> chronic infection
--May be asymptomatic

22

Describe the HBV genome

Circular, partially double stranded DNA.
Full length (-), 20-80% (+)

23

Describe the process of HBV replication

Genome is circular (-) DNA with partial (+) DNA. In nucleus, cellular DNApol -> full dsDNA
(-) DNA -> full length (+) RNA via host cell RNA pol II
(+) RNA is packaged in new core proteins
viral RNA/DNA dependent DNApol -> full length (-)DNA
(-)DNA copied by viral DNApol -> partial (+) DNA
HBsAg containing envelope acquired on exocytosis

24

How is HBV prevented / treated?

Recombinant vaccine
Interferon - alpha and/or inhibitors of HBV polymerase

**These do not eliminate infection***

25

Describe Hep D'd genome and what it codes

Small (-)RNA genome (1.7kb)
codes one protein: delta antigen: RNA encapsidation

26

What is HDV superinfection?

Infection w/ HDV after host is already infected with HBV.
contrast w/ coinfection, where both acquired together
Superinfection -> high mortality (20%)

27

What family of viruses does HCV belong to?

Flavivirus

28

Describe HCVs genome

(+)ss linear RNA

29

How is HCV infection treated?

Combination of interferon-alpha and ribavirin
-can eliminate infection, but IFNa has unpleasant side-effects

2 new drugs w/ this mix -> 70-80% cure rate