Microbiology - Enteric viruses I & II - Rebecca Greenblatt

Question 1

Reoviruses have a segmented genome, which has what mode of gaining genetic diversity?

Answer 1

Reassortment

Question 2

Transmission: Rotavirus (reovirus)

Answer 2

fecal-oral

Question 3

Orthoreoviruses cause:

Answer 3

Mild GI symptoms

Question 4

Rotavirus causes severe:

Answer 4

dehydration, even though diarrhea is self-limited

Question 5

What cells does rotavirus act on?

Answer 5

The cells of the small intestinal villi

Question 6

What does rotavirus have that acts like an enterotoxin?

Answer 6

NSP4 - rotavirus nonstructural protein 4 - interferes with sodium transport pumps - profuse watery diarrhea

Question 7

Phylogeny: Rotavirus

Answer 7

ds RNA virus
+ sense
icosahedral
naked

Question 8

Phylogeny: Norovirus

Answer 8

ss RNA virus
- sense
icosahedral
naked

Question 9

Transmission: Norwalk virus (norovirus)

Answer 9

fecal-oral

Question 10

IU: Norwalk virus

Answer 10

low

Question 11

IU: Rotavirus

Answer 11

high

Question 12

Pathogenesis: Norovirus

Answer 12

Infection damages microvilli in small intestine → malabsorption

Question 13

Vomiting is more common in what enterovirus?

Answer 13

Norovirus - slows gastric emptying as comparing with rotavirus

Question 14

What is primary viremia?

Answer 14

Successful virus travels in blood to seed replication site(s). LOW LEVELS in blood.

Question 15

What is secondary viremia?

Answer 15

New virus travels from replication site(s) to shedding site(s). HIGHER LEVELS in blood.

Question 16

Phylogeny: Picornaviruses ie Poliovirus, Hep A, Coxsackievirus

Answer 16

Small
naked
icosahedral
\+ sense 
ss RNA

Question 17

Coxsackie A causes:

Answer 17

herpangina, hand-foot-and-mouth disease, acute hemorrhagic conjunctivitis

Question 18

Coxsackie B causes:

Answer 18

myocarditis
pleurodynia
meningitis

Question 19

Site of replication: Enteroviruses and Picornaviruses

Answer 19

All replicate in gut

Question 20

T/F: Poliovirus is human-restricted.

Answer 20

True

Question 21

How does poliovirus enter/infect epithelial/lymphoid cells in the gut lining?

Answer 21

CD155 receptor - found in gut AND cns gray matter cells

then spreads to the blood stream and regional lymph nodes

Question 22

How does nerve death occur in poliovirus?

Answer 22

Nerve death results both from lytic virus replication and overenthusiastic
immune response

Question 23

Viruses that produce polyproteins are vulnerable to what class of drugs?

Answer 23

Protease inhibitors

Question 24

Where is the location of acute poliomyelitis infection?

Answer 24

Infection of the anterior horn motor neurons of the spinal cord (muscle symptoms) and brain stem (respiratory symptoms)

Flaccid asymmetric weakness and muscle atrophy due to loss of motor neurons and denervation of their associated skeletal muscles

Of acute poliovirus infections, 1-2% result in neurologic symptoms.

Question 25

Transmission: Poliovirus

Answer 25

Fecal-oral

Question 26

Risk factors: paralytic poliomyelitis

Answer 26

young age, advanced age, recent hard exercise, tonsillectomy, pregnancy, immunosuppression

Question 27

________ can cause herpangina & has been associated with severe complications. Fatalities, mostly in infants aged 6-11 months, have been reported.

Answer 27

Enterovirus 71

Question 28

Most common cause of herpangina:

Answer 28

Coxsackie A | Enterovirus - picornavirus

Question 29

Symptoms of herpangina:

Answer 29

Acute febrile illness Small vesicular or ulcerative lesions on the posterior oropharyngeal structures Typically occurs during the summer Frequently in children, also young adults Coxsackie A

Question 30

What viruses are primarily resonsible for acute hemorrhagic conjunctivitis?

Answer 30

Coxsackie group A24 (CA24) and enterovirus E70 (EV70)

Question 31

Why should the use of topical steroids be avoided in the treatment of acute hemorrhagic conjunctivitis?

Answer 31

Treatment with topical steroids should be avoided : risk of microbial superinfection of the cornea

Question 32

Viral myocarditis is most commonly caused by:

Answer 32

Adenovirus; Enterovirus Coxsackie B - one of the more severe presentations

Question 33

T/F: In viral myocarditis, CK-MB and Troponin I may be elevated.

Answer 33

True

Question 34

What is pleurodynia?

Answer 34

Pleurodynia (ploor-uh-din-ee-uh) (“Devil’s Grip”) is an uncommon complication of infection by coxsackievirus B or a few others Sudden occurrence of lancinating chest pain attacks Fever Malaise Headache

Question 35

What is the anatomic structure targeted by pleurodynia?

Answer 35

The striated muscle is the actual anatomic structure targeted by the coxsackievirus B and is responsible for the attacks of severe chest pain.

Question 36

Transmission: Coxackie B

Answer 36

Fecal-oral

Question 37

What physical exam finding points in the direction of pleurodynia/Coxsackie B infection?

Answer 37

Pleural/friction rub on lung exam

Question 38

When is pleurodynia life-threatening?

Answer 38

Infants

Question 39

In the developed world, >85% of aseptic/viral meningitis is caused by:

Answer 39

Enteroviruses

Question 40

Very young children with aseptic meningitis can present with what unique symptoms?

Answer 40

Fever w/ cold hands and feet; Fretful, dislike of being handled, pale, blotchy skin; blank staring/unresponsive

Question 41

Enteroviruses and HSV can cause _______ in infants

Answer 41

septic shock

Question 42

Ospithotonic positioning may be a sign of _______ or may be seen in an infant who is attempting to compensate for airway edema or stridor.

Answer 42

meningitis