Viruses of Gastrointestinal Illness

Question 1

Rotavirus

Answer 1

Most common viral cause of severe diarrhea in young children. Almost all children are infected by the age of 3-5 years.

Question 2

Clinical Manifestations of Rotavirus

Answer 2

Infants/young children (6-24 mo), can be anywhere from asymptomatic to severe dehydrating gastroenteritis with fever, vomiting, and WD.

Question 3

Transmission of rotavirus

Answer 3

Mostly fecal-oral and can include fomites because the virus is resistant to desiccation. Large number of rotavirus particles shed prior to, during, and even after illness. Some evidence of respiratory spread

Question 4

Incubation time of rotavirus

Answer 4

<48hours

Question 5

Diagnosis of rotavirus?

Answer 5

Elisa or latex agglutination to detect viral antigen in stool samples, RT PCR, isolation in cell culture is possible

Question 6

Classification of Rotavirus

Answer 6

Genus in the family Reoviridae

Question 7

How many serogroups of rotavirus

Answer 7

7 A-G
A, B, and C found in both animals and humans
D-G found only in animals.

Serotypes within serogroups

Question 8

VP6

Answer 8

Rotavirus serogroup determined by reactivity of antibodies with VP6 on ELISA

Question 9

Which serotypes most important for human disease?

Answer 9

Group A G1, G2, G3 and G4

Question 10

How to determine seroTYPE

Answer 10

Based on reactivity of antibodies with VP7 or VP4 (P antigen).

Question 11

Function of NSP4

Answer 11

ER protein/assembly enterotoxin, plays an important role is diarrhea

Question 12

Rotavirus structure

Answer 12

Wheel like shape, non enveloped virus with 3 layer (double layered capsid and core) protein structure. Segmented double stranded RNA.

Question 13

3 layer structure component proteins

Answer 13

VP4 and VP7 are outer capsid proteins
VP6 is inner capsid protein
VP2 is core protein

Question 14

Where does rotavirus replicate?

Answer 14

In the cytoplasm of the cell

Question 15

P antigen

Answer 15

VP4

Question 16

G antigen

Answer 16

VP7

Question 17

Rotavirus replication cycle

Answer 17

Replication within cytoplasm, only viral enzymes used, dsRNA always is associated with subviral particles, subviral particles form and mature by budding through the ER where outer capsid proteins are acquired.

Question 18

How does RNA synthesis by dsRNA viruses work?

Answer 18

Full length + sense RNAs are created to make protein and contribute to replication

Question 19

pathogenesis of rotavirus

Answer 19

Diarrhea begins before significant damage to the intestinal mucosa occurs, this is what distinguishes rotavirus diarrhea from bacterial diarrhea. Also, viremia occurs. PIP3 mediated release of calcium which causes secretory diarrhea.

Question 20

Immunity to rotavirus

Answer 20

First infection induces homotypic immunity against VP7 and VP4, subsequent infections induce more cross protective immunity. Antibodies in the lumen of small intestine are most important for protection, but T cells are also important.

Question 21

RotaTeq

Answer 21

A live pentavalent human-bovine rotavirus reassortant vaccine, licensed for infants younger than 32 weeks, given in 3 oral doses.

Question 22

Rotarix

Answer 22

Monovalent rotavirus vaccine derived from most common human rotavirus strain, attenuated by serial passage.

Question 23

Intussuseption

Answer 23

When a part of the intestine invaginates into a neighboring section, a complication of a certain rotavirus vaccine that was discontinued.

Question 24

Norovirus clinical manifestations

Answer 24

Acute gastroenteritis, most common cause of nonbacterial gastroenteritis outbreaks. Fevers, vomiting, watery diarrhea, constitutional symptoms. Adults tend to have diarrhea, children tend to vomit.

Question 25

What family do noroviruses belong to?

Answer 25

Cliciviridae. Sapporo-like viruses also belong to this family.

Question 26

Norovirus characteristics

Answer 26

Non-enveloped, single + sense linear RNA genome, replicates in the cytoplasm of the cell in the upper GI tract.

Question 27

Norovirus transmission

Answer 27

Fecal oral spread, also through fomites

Question 28

Norovirus incubation

Answer 28

1-2 days, illness lasts 1-2 days

Question 29

How long does viral shedding persist?

Answer 29

2 weeks

Question 30

Immunity to norovirus

Answer 30

Short lasting after illness mediated by antibodies, but some individuals seem to be generally resistant to the norovirus

Question 31

Se-

Answer 31

Secretor negatives. A phenotype due to the mutation in the FUT2 gene.

Question 32

Other viruses that cause GI symptoms

Answer 32

Enteric adenoviruses, astroviruses.