Viral Gastroenteritis

Question 1

What is the most common transmission route for viral gastroenteritis?

Answer 1

fecal to oral route

Question 2

True or false: viral gastroenteritis is only human to human transmission

Answer 2

false - some are animal to human

Question 3

What type of diarrhea is caused by viral gastroenteritis?

Answer 3

secreotry

Question 4

True or false: viral gastroenteritis diarrhea contains high levels of leukocytes?

Answer 4

false

Question 5

True or false: viral gastroenteritis diarrhea typically does not contain blood.

Answer 5

true

Question 6

What are the common symptoms of viral gastroenteritis?

Answer 6

nausea, vomiting, abdominal pain and diarrhea

Question 7

What are the two most common viruses causing viral gastroenteritis?

Answer 7

rotavirus

norovirus

Question 8

What are two lesser causes of viral gastroenteritis?

Answer 8

adenovirus

astrovirus

Question 9

Which one has a predilection for the winter: rotavirus or norovirus?

Answer 9

rotavirus

norovirus happens all year round

Question 10

Which one affects children?

Answer 10

rotavirus (younger than 5 typically_

Question 11

What is norovirus particularly associated with?

Answer 11

contaminated food and water causes outbreaks in adults

Question 12

What are the three big bacterial culprits for gastroenteritis?

Answer 12

salmonella
clostridium perfringens
camylobater

Question 13

For rotavirus, RNA or DNA? genome?

Answer 13

RNA

DS segmented - class III

SUPER RARE

Question 14

Describe the capsid for rotavirus.

Answer 14

it’s an icosahedral nucleocapsid with a DOUBLE SHELL!

Question 15

The unique structure of rotavirus’s genome allows it to do what?

Answer 15

reassort - like with influenza

Question 16

True or false: rotavirus affects humans and other vertebrates and often affects multiple species.

Answer 16

false - rotaviruses generally can affect both humans and other vertebrates but they exhibit substantial host-range restriction so the straings that affect humans only affect humans

Question 17

What is the tropism for rotavirus?

Answer 17

mature absorptive villous epithelium of the upper two thirds of the small itnestine

Question 18

What layer of the small intestine is rotavirus infection kept to?

Answer 18

the intestinal mucosa

Question 19

Describe in general what happens in the cell after the rotavirus virion has entered it?

Answer 19

1. capsid is shed and RNA genome released
2. viral RNA-dependent RNA polymerase and other enzymes start to transcribe the RNA into mRNA
3. mRNA is read by host machinery to translate into proteins
4. virus particles generated
5. leave the cell by lysis

Question 20

True or false: the released virion particles are immediately infectious and will affect the cells in the same area?

Answer 20

false - the outer layer of the capsid needs to mature under lumen conditions before it can be infectious

will typically move down into the distal small bowel before that occurs

Question 21

What characteristic does rotavirus have that is usually reserved for bacterial virulence factors?

Answer 21

it has a toxin

Question 22

What is rotavirus’ toxin?

Answer 22

NSP4 - it will form a pore in the enterocyte so it lyses

Question 23

How long does it take befor eyou can see cytoplasmic inclusions in the enterocytes where viral replication is taking place?

Answer 23

only 8 hours

Question 24

At the height of infection with rotavirus, how many viral particles will be released per gram of stool?

Answer 24

10 billion

Question 25

What are some of the reasons why rotavirus has such high death rates in the developing world?

Answer 25

1. treatment is supportive so you need access to hospitals and clean water 2. malnourishment makes it worse - especially vitamin deficiencies

Question 26

What vitamin will often be given in addition to IV fluids for children with rotavirus in developing countries?

Answer 26

vitamin A

Question 27

What are the two vaccines for rotavirus and how do they differ?

Answer 27

rotarix - human-infecting rotavirus proteins (attenuated) rotateq - human and cow rotavirus proteins (even more attenuated)

Question 28

Is norovirus an RNA or DNA virus? genome?

Answer 28

``` RNA virus SS+ nonsegmented - class IV (caliciviridae) ```

Question 29

Describe the norovirus capsid.

Answer 29

it's an icosahedral nucleocapsid ragged outline (differs from other caliciviruses that have cup-shaped indentations or a star shape)

Question 30

Is norovirus enveloped?

Answer 30

no

Question 31

What symptoms will come with norovirus?

Answer 31

lower fever than rotavirus (not over 101) severe vomiting diarrhea, nausea, abdominal cramps

Question 32

What piece of evidence gets at the massive prevalence of norovirus?

Answer 32

75% of people iwll have antibody response to norovirus by age 7

Question 33

How long do symptoms last? How long do you shed the virus?

Answer 33

2-3 days | 2-3 weeks

Question 34

How many virus particles of norovirus are released per gram of stool?

Answer 34

100 billion

Question 35

Why is immunity to norovirus so short lived?

Answer 35

the RNA-dependent RNA polymerase makes a lot of mustakes and introduces lots of mutations. DRIFT this means there are TONS of different strains

Question 36

What strain of norovirus emerged in march of 2012 and is not the dominant strain causing both cruise ship and land-based outbreaks worldwide?

Answer 36

GII.4 Syndey

Question 37

What serotypes of adenovirus can cause gastroenteritis?

Answer 37

40, 41, 42

Question 38

Is adenovirus a DNA or RNA virus? genome?

Answer 38

DNA DS DNA linear (class I)

Question 39

What is the capsid for adenovirus? Envelope?

Answer 39

icosahedral, nonenveloped

Question 40

Do the enteric adenoviruses have a vaccine?

Answer 40

no

Question 41

Although it's not usually done, how can you make a laboratory diagnosis of adenovirus gastroenteritis?

Answer 41

you need to do direct analysis of the stool with immunoassays or PCR?DNA probes because the serotypes 40-42 don't grow in culture